Linux 4.18.10

[linux/fpc-iii.git] / drivers / char / ipmi / ipmi_msghandler.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * ipmi_msghandler.c
 *
 * Incoming and outgoing message routing for an IPMI interface.
 *
 * Author: MontaVista Software, Inc.
 *         Corey Minyard <minyard@mvista.com>
 *         source@mvista.com
 *
 * Copyright 2002 MontaVista Software Inc.
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/ipmi.h>
#include <linux/ipmi_smi.h>
#include <linux/notifier.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/rcupdate.h>
#include <linux/interrupt.h>
#include <linux/moduleparam.h>
#include <linux/workqueue.h>
#include <linux/uuid.h>

#define PFX "IPMI message handler: "

#define IPMI_DRIVER_VERSION "39.2"

static struct ipmi_recv_msg *ipmi_alloc_recv_msg(void);
static int ipmi_init_msghandler(void);
static void smi_recv_tasklet(unsigned long);
static void handle_new_recv_msgs(struct ipmi_smi *intf);
static void need_waiter(struct ipmi_smi *intf);
static int handle_one_recv_msg(struct ipmi_smi *intf,
                               struct ipmi_smi_msg *msg);

#ifdef DEBUG
static void ipmi_debug_msg(const char *title, unsigned char *data,
                           unsigned int len)
{
        int i, pos;
        char buf[100];

        pos = snprintf(buf, sizeof(buf), "%s: ", title);
        for (i = 0; i < len; i++)
                pos += snprintf(buf + pos, sizeof(buf) - pos,
                                " %2.2x", data[i]);
        pr_debug("%s\n", buf);
}
#else
static void ipmi_debug_msg(const char *title, unsigned char *data,
                           unsigned int len)
{ }
#endif

static int initialized;

enum ipmi_panic_event_op {
        IPMI_SEND_PANIC_EVENT_NONE,
        IPMI_SEND_PANIC_EVENT,
        IPMI_SEND_PANIC_EVENT_STRING
};
#ifdef CONFIG_IPMI_PANIC_STRING
#define IPMI_PANIC_DEFAULT IPMI_SEND_PANIC_EVENT_STRING
#elif defined(CONFIG_IPMI_PANIC_EVENT)
#define IPMI_PANIC_DEFAULT IPMI_SEND_PANIC_EVENT
#else
#define IPMI_PANIC_DEFAULT IPMI_SEND_PANIC_EVENT_NONE
#endif
static enum ipmi_panic_event_op ipmi_send_panic_event = IPMI_PANIC_DEFAULT;

static int panic_op_write_handler(const char *val,
                                  const struct kernel_param *kp)
{
        char valcp[16];
        char *s;

        strncpy(valcp, val, 15);
        valcp[15] = '\0';

        s = strstrip(valcp);

        if (strcmp(s, "none") == 0)
                ipmi_send_panic_event = IPMI_SEND_PANIC_EVENT_NONE;
        else if (strcmp(s, "event") == 0)
                ipmi_send_panic_event = IPMI_SEND_PANIC_EVENT;
        else if (strcmp(s, "string") == 0)
                ipmi_send_panic_event = IPMI_SEND_PANIC_EVENT_STRING;
        else
                return -EINVAL;

        return 0;
}

static int panic_op_read_handler(char *buffer, const struct kernel_param *kp)
{
        switch (ipmi_send_panic_event) {
        case IPMI_SEND_PANIC_EVENT_NONE:
                strcpy(buffer, "none");
                break;

        case IPMI_SEND_PANIC_EVENT:
                strcpy(buffer, "event");
                break;

        case IPMI_SEND_PANIC_EVENT_STRING:
                strcpy(buffer, "string");
                break;

        default:
                strcpy(buffer, "???");
                break;
        }

        return strlen(buffer);
}

static const struct kernel_param_ops panic_op_ops = {
        .set = panic_op_write_handler,
        .get = panic_op_read_handler
};
module_param_cb(panic_op, &panic_op_ops, NULL, 0600);
MODULE_PARM_DESC(panic_op, "Sets if the IPMI driver will attempt to store panic information in the event log in the event of a panic.  Set to 'none' for no, 'event' for a single event, or 'string' for a generic event and the panic string in IPMI OEM events.");


#define MAX_EVENTS_IN_QUEUE     25

/* Remain in auto-maintenance mode for this amount of time (in ms). */
static unsigned long maintenance_mode_timeout_ms = 30000;
module_param(maintenance_mode_timeout_ms, ulong, 0644);
MODULE_PARM_DESC(maintenance_mode_timeout_ms,
                 "The time (milliseconds) after the last maintenance message that the connection stays in maintenance mode.");

/*
 * Don't let a message sit in a queue forever, always time it with at lest
 * the max message timer.  This is in milliseconds.
 */
#define MAX_MSG_TIMEOUT         60000

/*
 * Timeout times below are in milliseconds, and are done off a 1
 * second timer.  So setting the value to 1000 would mean anything
 * between 0 and 1000ms.  So really the only reasonable minimum
 * setting it 2000ms, which is between 1 and 2 seconds.
 */

/* The default timeout for message retries. */
static unsigned long default_retry_ms = 2000;
module_param(default_retry_ms, ulong, 0644);
MODULE_PARM_DESC(default_retry_ms,
                 "The time (milliseconds) between retry sends");

/* The default timeout for maintenance mode message retries. */
static unsigned long default_maintenance_retry_ms = 3000;
module_param(default_maintenance_retry_ms, ulong, 0644);
MODULE_PARM_DESC(default_maintenance_retry_ms,
                 "The time (milliseconds) between retry sends in maintenance mode");

/* The default maximum number of retries */
static unsigned int default_max_retries = 4;
module_param(default_max_retries, uint, 0644);
MODULE_PARM_DESC(default_max_retries,
                 "The time (milliseconds) between retry sends in maintenance mode");

/* Call every ~1000 ms. */
#define IPMI_TIMEOUT_TIME       1000

/* How many jiffies does it take to get to the timeout time. */
#define IPMI_TIMEOUT_JIFFIES    ((IPMI_TIMEOUT_TIME * HZ) / 1000)

/*
 * Request events from the queue every second (this is the number of
 * IPMI_TIMEOUT_TIMES between event requests).  Hopefully, in the
 * future, IPMI will add a way to know immediately if an event is in
 * the queue and this silliness can go away.
 */
#define IPMI_REQUEST_EV_TIME    (1000 / (IPMI_TIMEOUT_TIME))

/* How long should we cache dynamic device IDs? */
#define IPMI_DYN_DEV_ID_EXPIRY  (10 * HZ)

/*
 * The main "user" data structure.
 */
struct ipmi_user {
        struct list_head link;

        /*
         * Set to NULL when the user is destroyed, a pointer to myself
         * so srcu_dereference can be used on it.
         */
        struct ipmi_user *self;
        struct srcu_struct release_barrier;

        struct kref refcount;

        /* The upper layer that handles receive messages. */
        const struct ipmi_user_hndl *handler;
        void             *handler_data;

        /* The interface this user is bound to. */
        struct ipmi_smi *intf;

        /* Does this interface receive IPMI events? */
        bool gets_events;
};

static struct ipmi_user *acquire_ipmi_user(struct ipmi_user *user, int *index)
        __acquires(user->release_barrier)
{
        struct ipmi_user *ruser;

        *index = srcu_read_lock(&user->release_barrier);
        ruser = srcu_dereference(user->self, &user->release_barrier);
        if (!ruser)
                srcu_read_unlock(&user->release_barrier, *index);
        return ruser;
}

static void release_ipmi_user(struct ipmi_user *user, int index)
{
        srcu_read_unlock(&user->release_barrier, index);
}

struct cmd_rcvr {
        struct list_head link;

        struct ipmi_user *user;
        unsigned char netfn;
        unsigned char cmd;
        unsigned int  chans;

        /*
         * This is used to form a linked lised during mass deletion.
         * Since this is in an RCU list, we cannot use the link above
         * or change any data until the RCU period completes.  So we
         * use this next variable during mass deletion so we can have
         * a list and don't have to wait and restart the search on
         * every individual deletion of a command.
         */
        struct cmd_rcvr *next;
};

struct seq_table {
        unsigned int         inuse : 1;
        unsigned int         broadcast : 1;

        unsigned long        timeout;
        unsigned long        orig_timeout;
        unsigned int         retries_left;

        /*
         * To verify on an incoming send message response that this is
         * the message that the response is for, we keep a sequence id
         * and increment it every time we send a message.
         */
        long                 seqid;

        /*
         * This is held so we can properly respond to the message on a
         * timeout, and it is used to hold the temporary data for
         * retransmission, too.
         */
        struct ipmi_recv_msg *recv_msg;
};

/*
 * Store the information in a msgid (long) to allow us to find a
 * sequence table entry from the msgid.
 */
#define STORE_SEQ_IN_MSGID(seq, seqid) \
        ((((seq) & 0x3f) << 26) | ((seqid) & 0x3ffffff))

#define GET_SEQ_FROM_MSGID(msgid, seq, seqid) \
        do {                                                            \
                seq = (((msgid) >> 26) & 0x3f);                         \
                seqid = ((msgid) & 0x3ffffff);                          \
        } while (0)

#define NEXT_SEQID(seqid) (((seqid) + 1) & 0x3ffffff)

#define IPMI_MAX_CHANNELS       16
struct ipmi_channel {
        unsigned char medium;
        unsigned char protocol;
};

struct ipmi_channel_set {
        struct ipmi_channel c[IPMI_MAX_CHANNELS];
};

struct ipmi_my_addrinfo {
        /*
         * My slave address.  This is initialized to IPMI_BMC_SLAVE_ADDR,
         * but may be changed by the user.
         */
        unsigned char address;

        /*
         * My LUN.  This should generally stay the SMS LUN, but just in
         * case...
         */
        unsigned char lun;
};

/*
 * Note that the product id, manufacturer id, guid, and device id are
 * immutable in this structure, so dyn_mutex is not required for
 * accessing those.  If those change on a BMC, a new BMC is allocated.
 */
struct bmc_device {
        struct platform_device pdev;
        struct list_head       intfs; /* Interfaces on this BMC. */
        struct ipmi_device_id  id;
        struct ipmi_device_id  fetch_id;
        int                    dyn_id_set;
        unsigned long          dyn_id_expiry;
        struct mutex           dyn_mutex; /* Protects id, intfs, & dyn* */
        guid_t                 guid;
        guid_t                 fetch_guid;
        int                    dyn_guid_set;
        struct kref            usecount;
        struct work_struct     remove_work;
};
#define to_bmc_device(x) container_of((x), struct bmc_device, pdev.dev)

static int bmc_get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc,
                             struct ipmi_device_id *id,
                             bool *guid_set, guid_t *guid);

/*
 * Various statistics for IPMI, these index stats[] in the ipmi_smi
 * structure.
 */
enum ipmi_stat_indexes {
        /* Commands we got from the user that were invalid. */
        IPMI_STAT_sent_invalid_commands = 0,

        /* Commands we sent to the MC. */
        IPMI_STAT_sent_local_commands,

        /* Responses from the MC that were delivered to a user. */
        IPMI_STAT_handled_local_responses,

        /* Responses from the MC that were not delivered to a user. */
        IPMI_STAT_unhandled_local_responses,

        /* Commands we sent out to the IPMB bus. */
        IPMI_STAT_sent_ipmb_commands,

        /* Commands sent on the IPMB that had errors on the SEND CMD */
        IPMI_STAT_sent_ipmb_command_errs,

        /* Each retransmit increments this count. */
        IPMI_STAT_retransmitted_ipmb_commands,

        /*
         * When a message times out (runs out of retransmits) this is
         * incremented.
         */
        IPMI_STAT_timed_out_ipmb_commands,

        /*
         * This is like above, but for broadcasts.  Broadcasts are
         * *not* included in the above count (they are expected to
         * time out).
         */
        IPMI_STAT_timed_out_ipmb_broadcasts,

        /* Responses I have sent to the IPMB bus. */
        IPMI_STAT_sent_ipmb_responses,

        /* The response was delivered to the user. */
        IPMI_STAT_handled_ipmb_responses,

        /* The response had invalid data in it. */
        IPMI_STAT_invalid_ipmb_responses,

        /* The response didn't have anyone waiting for it. */
        IPMI_STAT_unhandled_ipmb_responses,

        /* Commands we sent out to the IPMB bus. */
        IPMI_STAT_sent_lan_commands,

        /* Commands sent on the IPMB that had errors on the SEND CMD */
        IPMI_STAT_sent_lan_command_errs,

        /* Each retransmit increments this count. */
        IPMI_STAT_retransmitted_lan_commands,

        /*
         * When a message times out (runs out of retransmits) this is
         * incremented.
         */
        IPMI_STAT_timed_out_lan_commands,

        /* Responses I have sent to the IPMB bus. */
        IPMI_STAT_sent_lan_responses,

        /* The response was delivered to the user. */
        IPMI_STAT_handled_lan_responses,

        /* The response had invalid data in it. */
        IPMI_STAT_invalid_lan_responses,

        /* The response didn't have anyone waiting for it. */
        IPMI_STAT_unhandled_lan_responses,

        /* The command was delivered to the user. */
        IPMI_STAT_handled_commands,

        /* The command had invalid data in it. */
        IPMI_STAT_invalid_commands,

        /* The command didn't have anyone waiting for it. */
        IPMI_STAT_unhandled_commands,

        /* Invalid data in an event. */
        IPMI_STAT_invalid_events,

        /* Events that were received with the proper format. */
        IPMI_STAT_events,

        /* Retransmissions on IPMB that failed. */
        IPMI_STAT_dropped_rexmit_ipmb_commands,

        /* Retransmissions on LAN that failed. */
        IPMI_STAT_dropped_rexmit_lan_commands,

        /* This *must* remain last, add new values above this. */
        IPMI_NUM_STATS
};


#define IPMI_IPMB_NUM_SEQ       64
struct ipmi_smi {
        /* What interface number are we? */
        int intf_num;

        struct kref refcount;

        /* Set when the interface is being unregistered. */
        bool in_shutdown;

        /* Used for a list of interfaces. */
        struct list_head link;

        /*
         * The list of upper layers that are using me.  seq_lock write
         * protects this.  Read protection is with srcu.
         */
        struct list_head users;
        struct srcu_struct users_srcu;

        /* Used for wake ups at startup. */
        wait_queue_head_t waitq;

        /*
         * Prevents the interface from being unregistered when the
         * interface is used by being looked up through the BMC
         * structure.
         */
        struct mutex bmc_reg_mutex;

        struct bmc_device tmp_bmc;
        struct bmc_device *bmc;
        bool bmc_registered;
        struct list_head bmc_link;
        char *my_dev_name;
        bool in_bmc_register;  /* Handle recursive situations.  Yuck. */
        struct work_struct bmc_reg_work;

        const struct ipmi_smi_handlers *handlers;
        void                     *send_info;

        /* Driver-model device for the system interface. */
        struct device          *si_dev;

        /*
         * A table of sequence numbers for this interface.  We use the
         * sequence numbers for IPMB messages that go out of the
         * interface to match them up with their responses.  A routine
         * is called periodically to time the items in this list.
         */
        spinlock_t       seq_lock;
        struct seq_table seq_table[IPMI_IPMB_NUM_SEQ];
        int curr_seq;

        /*
         * Messages queued for delivery.  If delivery fails (out of memory
         * for instance), They will stay in here to be processed later in a
         * periodic timer interrupt.  The tasklet is for handling received
         * messages directly from the handler.
         */
        spinlock_t       waiting_rcv_msgs_lock;
        struct list_head waiting_rcv_msgs;
        atomic_t         watchdog_pretimeouts_to_deliver;
        struct tasklet_struct recv_tasklet;

        spinlock_t             xmit_msgs_lock;
        struct list_head       xmit_msgs;
        struct ipmi_smi_msg    *curr_msg;
        struct list_head       hp_xmit_msgs;

        /*
         * The list of command receivers that are registered for commands
         * on this interface.
         */
        struct mutex     cmd_rcvrs_mutex;
        struct list_head cmd_rcvrs;

        /*
         * Events that were queues because no one was there to receive
         * them.
         */
        spinlock_t       events_lock; /* For dealing with event stuff. */
        struct list_head waiting_events;
        unsigned int     waiting_events_count; /* How many events in queue? */
        char             delivering_events;
        char             event_msg_printed;
        atomic_t         event_waiters;
        unsigned int     ticks_to_req_ev;
        int              last_needs_timer;

        /*
         * The event receiver for my BMC, only really used at panic
         * shutdown as a place to store this.
         */
        unsigned char event_receiver;
        unsigned char event_receiver_lun;
        unsigned char local_sel_device;
        unsigned char local_event_generator;

        /* For handling of maintenance mode. */
        int maintenance_mode;
        bool maintenance_mode_enable;
        int auto_maintenance_timeout;
        spinlock_t maintenance_mode_lock; /* Used in a timer... */

        /*
         * If we are doing maintenance on something on IPMB, extend
         * the timeout time to avoid timeouts writing firmware and
         * such.
         */
        int ipmb_maintenance_mode_timeout;

        /*
         * A cheap hack, if this is non-null and a message to an
         * interface comes in with a NULL user, call this routine with
         * it.  Note that the message will still be freed by the
         * caller.  This only works on the system interface.
         *
         * Protected by bmc_reg_mutex.
         */
        void (*null_user_handler)(struct ipmi_smi *intf,
                                  struct ipmi_recv_msg *msg);

        /*
         * When we are scanning the channels for an SMI, this will
         * tell which channel we are scanning.
         */
        int curr_channel;

        /* Channel information */
        struct ipmi_channel_set *channel_list;
        unsigned int curr_working_cset; /* First index into the following. */
        struct ipmi_channel_set wchannels[2];
        struct ipmi_my_addrinfo addrinfo[IPMI_MAX_CHANNELS];
        bool channels_ready;

        atomic_t stats[IPMI_NUM_STATS];

        /*
         * run_to_completion duplicate of smb_info, smi_info
         * and ipmi_serial_info structures. Used to decrease numbers of
         * parameters passed by "low" level IPMI code.
         */
        int run_to_completion;
};
#define to_si_intf_from_dev(device) container_of(device, struct ipmi_smi, dev)

static void __get_guid(struct ipmi_smi *intf);
static void __ipmi_bmc_unregister(struct ipmi_smi *intf);
static int __ipmi_bmc_register(struct ipmi_smi *intf,
                               struct ipmi_device_id *id,
                               bool guid_set, guid_t *guid, int intf_num);
static int __scan_channels(struct ipmi_smi *intf, struct ipmi_device_id *id);


/**
 * The driver model view of the IPMI messaging driver.
 */
static struct platform_driver ipmidriver = {
        .driver = {
                .name = "ipmi",
                .bus = &platform_bus_type
        }
};
/*
 * This mutex keeps us from adding the same BMC twice.
 */
static DEFINE_MUTEX(ipmidriver_mutex);

static LIST_HEAD(ipmi_interfaces);
static DEFINE_MUTEX(ipmi_interfaces_mutex);
DEFINE_STATIC_SRCU(ipmi_interfaces_srcu);

/*
 * List of watchers that want to know when smi's are added and deleted.
 */
static LIST_HEAD(smi_watchers);
static DEFINE_MUTEX(smi_watchers_mutex);

#define ipmi_inc_stat(intf, stat) \
        atomic_inc(&(intf)->stats[IPMI_STAT_ ## stat])
#define ipmi_get_stat(intf, stat) \
        ((unsigned int) atomic_read(&(intf)->stats[IPMI_STAT_ ## stat]))

static const char * const addr_src_to_str[] = {
        "invalid", "hotmod", "hardcoded", "SPMI", "ACPI", "SMBIOS", "PCI",
        "device-tree", "platform"
};

const char *ipmi_addr_src_to_str(enum ipmi_addr_src src)
{
        if (src >= SI_LAST)
                src = 0; /* Invalid */
        return addr_src_to_str[src];
}
EXPORT_SYMBOL(ipmi_addr_src_to_str);

static int is_lan_addr(struct ipmi_addr *addr)
{
        return addr->addr_type == IPMI_LAN_ADDR_TYPE;
}

static int is_ipmb_addr(struct ipmi_addr *addr)
{
        return addr->addr_type == IPMI_IPMB_ADDR_TYPE;
}

static int is_ipmb_bcast_addr(struct ipmi_addr *addr)
{
        return addr->addr_type == IPMI_IPMB_BROADCAST_ADDR_TYPE;
}

static void free_recv_msg_list(struct list_head *q)
{
        struct ipmi_recv_msg *msg, *msg2;

        list_for_each_entry_safe(msg, msg2, q, link) {
                list_del(&msg->link);
                ipmi_free_recv_msg(msg);
        }
}

static void free_smi_msg_list(struct list_head *q)
{
        struct ipmi_smi_msg *msg, *msg2;

        list_for_each_entry_safe(msg, msg2, q, link) {
                list_del(&msg->link);
                ipmi_free_smi_msg(msg);
        }
}

static void clean_up_interface_data(struct ipmi_smi *intf)
{
        int              i;
        struct cmd_rcvr  *rcvr, *rcvr2;
        struct list_head list;

        tasklet_kill(&intf->recv_tasklet);

        free_smi_msg_list(&intf->waiting_rcv_msgs);
        free_recv_msg_list(&intf->waiting_events);

        /*
         * Wholesale remove all the entries from the list in the
         * interface and wait for RCU to know that none are in use.
         */
        mutex_lock(&intf->cmd_rcvrs_mutex);
        INIT_LIST_HEAD(&list);
        list_splice_init_rcu(&intf->cmd_rcvrs, &list, synchronize_rcu);
        mutex_unlock(&intf->cmd_rcvrs_mutex);

        list_for_each_entry_safe(rcvr, rcvr2, &list, link)
                kfree(rcvr);

        for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
                if ((intf->seq_table[i].inuse)
                                        && (intf->seq_table[i].recv_msg))
                        ipmi_free_recv_msg(intf->seq_table[i].recv_msg);
        }
}

static void intf_free(struct kref *ref)
{
        struct ipmi_smi *intf = container_of(ref, struct ipmi_smi, refcount);

        clean_up_interface_data(intf);
        kfree(intf);
}

struct watcher_entry {
        int              intf_num;
        struct ipmi_smi  *intf;
        struct list_head link;
};

int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
{
        struct ipmi_smi *intf;
        int index;

        mutex_lock(&smi_watchers_mutex);

        list_add(&watcher->link, &smi_watchers);

        index = srcu_read_lock(&ipmi_interfaces_srcu);
        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
                int intf_num = READ_ONCE(intf->intf_num);

                if (intf_num == -1)
                        continue;
                watcher->new_smi(intf_num, intf->si_dev);
        }
        srcu_read_unlock(&ipmi_interfaces_srcu, index);

        mutex_unlock(&smi_watchers_mutex);

        return 0;
}
EXPORT_SYMBOL(ipmi_smi_watcher_register);

int ipmi_smi_watcher_unregister(struct ipmi_smi_watcher *watcher)
{
        mutex_lock(&smi_watchers_mutex);
        list_del(&watcher->link);
        mutex_unlock(&smi_watchers_mutex);
        return 0;
}
EXPORT_SYMBOL(ipmi_smi_watcher_unregister);

/*
 * Must be called with smi_watchers_mutex held.
 */
static void
call_smi_watchers(int i, struct device *dev)
{
        struct ipmi_smi_watcher *w;

        mutex_lock(&smi_watchers_mutex);
        list_for_each_entry(w, &smi_watchers, link) {
                if (try_module_get(w->owner)) {
                        w->new_smi(i, dev);
                        module_put(w->owner);
                }
        }
        mutex_unlock(&smi_watchers_mutex);
}

static int
ipmi_addr_equal(struct ipmi_addr *addr1, struct ipmi_addr *addr2)
{
        if (addr1->addr_type != addr2->addr_type)
                return 0;

        if (addr1->channel != addr2->channel)
                return 0;

        if (addr1->addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE) {
                struct ipmi_system_interface_addr *smi_addr1
                    = (struct ipmi_system_interface_addr *) addr1;
                struct ipmi_system_interface_addr *smi_addr2
                    = (struct ipmi_system_interface_addr *) addr2;
                return (smi_addr1->lun == smi_addr2->lun);
        }

        if (is_ipmb_addr(addr1) || is_ipmb_bcast_addr(addr1)) {
                struct ipmi_ipmb_addr *ipmb_addr1
                    = (struct ipmi_ipmb_addr *) addr1;
                struct ipmi_ipmb_addr *ipmb_addr2
                    = (struct ipmi_ipmb_addr *) addr2;

                return ((ipmb_addr1->slave_addr == ipmb_addr2->slave_addr)
                        && (ipmb_addr1->lun == ipmb_addr2->lun));
        }

        if (is_lan_addr(addr1)) {
                struct ipmi_lan_addr *lan_addr1
                        = (struct ipmi_lan_addr *) addr1;
                struct ipmi_lan_addr *lan_addr2
                    = (struct ipmi_lan_addr *) addr2;

                return ((lan_addr1->remote_SWID == lan_addr2->remote_SWID)
                        && (lan_addr1->local_SWID == lan_addr2->local_SWID)
                        && (lan_addr1->session_handle
                            == lan_addr2->session_handle)
                        && (lan_addr1->lun == lan_addr2->lun));
        }

        return 1;
}

int ipmi_validate_addr(struct ipmi_addr *addr, int len)
{
        if (len < sizeof(struct ipmi_system_interface_addr))
                return -EINVAL;

        if (addr->addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE) {
                if (addr->channel != IPMI_BMC_CHANNEL)
                        return -EINVAL;
                return 0;
        }

        if ((addr->channel == IPMI_BMC_CHANNEL)
            || (addr->channel >= IPMI_MAX_CHANNELS)
            || (addr->channel < 0))
                return -EINVAL;

        if (is_ipmb_addr(addr) || is_ipmb_bcast_addr(addr)) {
                if (len < sizeof(struct ipmi_ipmb_addr))
                        return -EINVAL;
                return 0;
        }

        if (is_lan_addr(addr)) {
                if (len < sizeof(struct ipmi_lan_addr))
                        return -EINVAL;
                return 0;
        }

        return -EINVAL;
}
EXPORT_SYMBOL(ipmi_validate_addr);

unsigned int ipmi_addr_length(int addr_type)
{
        if (addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE)
                return sizeof(struct ipmi_system_interface_addr);

        if ((addr_type == IPMI_IPMB_ADDR_TYPE)
                        || (addr_type == IPMI_IPMB_BROADCAST_ADDR_TYPE))
                return sizeof(struct ipmi_ipmb_addr);

        if (addr_type == IPMI_LAN_ADDR_TYPE)
                return sizeof(struct ipmi_lan_addr);

        return 0;
}
EXPORT_SYMBOL(ipmi_addr_length);

static int deliver_response(struct ipmi_smi *intf, struct ipmi_recv_msg *msg)
{
        int rv = 0;

        if (!msg->user) {
                /* Special handling for NULL users. */
                if (intf->null_user_handler) {
                        intf->null_user_handler(intf, msg);
                } else {
                        /* No handler, so give up. */
                        rv = -EINVAL;
                }
                ipmi_free_recv_msg(msg);
        } else if (!oops_in_progress) {
                /*
                 * If we are running in the panic context, calling the
                 * receive handler doesn't much meaning and has a deadlock
                 * risk.  At this moment, simply skip it in that case.
                 */
                int index;
                struct ipmi_user *user = acquire_ipmi_user(msg->user, &index);

                if (user) {
                        user->handler->ipmi_recv_hndl(msg, user->handler_data);
                        release_ipmi_user(msg->user, index);
                } else {
                        /* User went away, give up. */
                        ipmi_free_recv_msg(msg);
                        rv = -EINVAL;
                }
        }

        return rv;
}

static void deliver_local_response(struct ipmi_smi *intf,
                                   struct ipmi_recv_msg *msg)
{
        if (deliver_response(intf, msg))
                ipmi_inc_stat(intf, unhandled_local_responses);
        else
                ipmi_inc_stat(intf, handled_local_responses);
}

static void deliver_err_response(struct ipmi_smi *intf,
                                 struct ipmi_recv_msg *msg, int err)
{
        msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
        msg->msg_data[0] = err;
        msg->msg.netfn |= 1; /* Convert to a response. */
        msg->msg.data_len = 1;
        msg->msg.data = msg->msg_data;
        deliver_local_response(intf, msg);
}

/*
 * Find the next sequence number not being used and add the given
 * message with the given timeout to the sequence table.  This must be
 * called with the interface's seq_lock held.
 */
static int intf_next_seq(struct ipmi_smi      *intf,
                         struct ipmi_recv_msg *recv_msg,
                         unsigned long        timeout,
                         int                  retries,
                         int                  broadcast,
                         unsigned char        *seq,
                         long                 *seqid)
{
        int          rv = 0;
        unsigned int i;

        if (timeout == 0)
                timeout = default_retry_ms;
        if (retries < 0)
                retries = default_max_retries;

        for (i = intf->curr_seq; (i+1)%IPMI_IPMB_NUM_SEQ != intf->curr_seq;
                                        i = (i+1)%IPMI_IPMB_NUM_SEQ) {
                if (!intf->seq_table[i].inuse)
                        break;
        }

        if (!intf->seq_table[i].inuse) {
                intf->seq_table[i].recv_msg = recv_msg;

                /*
                 * Start with the maximum timeout, when the send response
                 * comes in we will start the real timer.
                 */
                intf->seq_table[i].timeout = MAX_MSG_TIMEOUT;
                intf->seq_table[i].orig_timeout = timeout;
                intf->seq_table[i].retries_left = retries;
                intf->seq_table[i].broadcast = broadcast;
                intf->seq_table[i].inuse = 1;
                intf->seq_table[i].seqid = NEXT_SEQID(intf->seq_table[i].seqid);
                *seq = i;
                *seqid = intf->seq_table[i].seqid;
                intf->curr_seq = (i+1)%IPMI_IPMB_NUM_SEQ;
                need_waiter(intf);
        } else {
                rv = -EAGAIN;
        }

        return rv;
}

/*
 * Return the receive message for the given sequence number and
 * release the sequence number so it can be reused.  Some other data
 * is passed in to be sure the message matches up correctly (to help
 * guard against message coming in after their timeout and the
 * sequence number being reused).
 */
static int intf_find_seq(struct ipmi_smi      *intf,
                         unsigned char        seq,
                         short                channel,
                         unsigned char        cmd,
                         unsigned char        netfn,
                         struct ipmi_addr     *addr,
                         struct ipmi_recv_msg **recv_msg)
{
        int           rv = -ENODEV;
        unsigned long flags;

        if (seq >= IPMI_IPMB_NUM_SEQ)
                return -EINVAL;

        spin_lock_irqsave(&intf->seq_lock, flags);
        if (intf->seq_table[seq].inuse) {
                struct ipmi_recv_msg *msg = intf->seq_table[seq].recv_msg;

                if ((msg->addr.channel == channel) && (msg->msg.cmd == cmd)
                                && (msg->msg.netfn == netfn)
                                && (ipmi_addr_equal(addr, &msg->addr))) {
                        *recv_msg = msg;
                        intf->seq_table[seq].inuse = 0;
                        rv = 0;
                }
        }
        spin_unlock_irqrestore(&intf->seq_lock, flags);

        return rv;
}


/* Start the timer for a specific sequence table entry. */
static int intf_start_seq_timer(struct ipmi_smi *intf,
                                long       msgid)
{
        int           rv = -ENODEV;
        unsigned long flags;
        unsigned char seq;
        unsigned long seqid;


        GET_SEQ_FROM_MSGID(msgid, seq, seqid);

        spin_lock_irqsave(&intf->seq_lock, flags);
        /*
         * We do this verification because the user can be deleted
         * while a message is outstanding.
         */
        if ((intf->seq_table[seq].inuse)
                                && (intf->seq_table[seq].seqid == seqid)) {
                struct seq_table *ent = &intf->seq_table[seq];
                ent->timeout = ent->orig_timeout;
                rv = 0;
        }
        spin_unlock_irqrestore(&intf->seq_lock, flags);

        return rv;
}

/* Got an error for the send message for a specific sequence number. */
static int intf_err_seq(struct ipmi_smi *intf,
                        long         msgid,
                        unsigned int err)
{
        int                  rv = -ENODEV;
        unsigned long        flags;
        unsigned char        seq;
        unsigned long        seqid;
        struct ipmi_recv_msg *msg = NULL;


        GET_SEQ_FROM_MSGID(msgid, seq, seqid);

        spin_lock_irqsave(&intf->seq_lock, flags);
        /*
         * We do this verification because the user can be deleted
         * while a message is outstanding.
         */
        if ((intf->seq_table[seq].inuse)
                                && (intf->seq_table[seq].seqid == seqid)) {
                struct seq_table *ent = &intf->seq_table[seq];

                ent->inuse = 0;
                msg = ent->recv_msg;
                rv = 0;
        }
        spin_unlock_irqrestore(&intf->seq_lock, flags);

        if (msg)
                deliver_err_response(intf, msg, err);

        return rv;
}


int ipmi_create_user(unsigned int          if_num,
                     const struct ipmi_user_hndl *handler,
                     void                  *handler_data,
                     struct ipmi_user      **user)
{
        unsigned long flags;
        struct ipmi_user *new_user;
        int           rv = 0, index;
        struct ipmi_smi *intf;

        /*
         * There is no module usecount here, because it's not
         * required.  Since this can only be used by and called from
         * other modules, they will implicitly use this module, and
         * thus this can't be removed unless the other modules are
         * removed.
         */

        if (handler == NULL)
                return -EINVAL;

        /*
         * Make sure the driver is actually initialized, this handles
         * problems with initialization order.
         */
        if (!initialized) {
                rv = ipmi_init_msghandler();
                if (rv)
                        return rv;

                /*
                 * The init code doesn't return an error if it was turned
                 * off, but it won't initialize.  Check that.
                 */
                if (!initialized)
                        return -ENODEV;
        }

        new_user = kmalloc(sizeof(*new_user), GFP_KERNEL);
        if (!new_user)
                return -ENOMEM;

        index = srcu_read_lock(&ipmi_interfaces_srcu);
        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
                if (intf->intf_num == if_num)
                        goto found;
        }
        /* Not found, return an error */
        rv = -EINVAL;
        goto out_kfree;

 found:
        rv = init_srcu_struct(&new_user->release_barrier);
        if (rv)
                goto out_kfree;

        /* Note that each existing user holds a refcount to the interface. */
        kref_get(&intf->refcount);

        kref_init(&new_user->refcount);
        new_user->handler = handler;
        new_user->handler_data = handler_data;
        new_user->intf = intf;
        new_user->gets_events = false;

        rcu_assign_pointer(new_user->self, new_user);
        spin_lock_irqsave(&intf->seq_lock, flags);
        list_add_rcu(&new_user->link, &intf->users);
        spin_unlock_irqrestore(&intf->seq_lock, flags);
        if (handler->ipmi_watchdog_pretimeout) {
                /* User wants pretimeouts, so make sure to watch for them. */
                if (atomic_inc_return(&intf->event_waiters) == 1)
                        need_waiter(intf);
        }
        srcu_read_unlock(&ipmi_interfaces_srcu, index);
        *user = new_user;
        return 0;

out_kfree:
        srcu_read_unlock(&ipmi_interfaces_srcu, index);
        kfree(new_user);
        return rv;
}
EXPORT_SYMBOL(ipmi_create_user);

int ipmi_get_smi_info(int if_num, struct ipmi_smi_info *data)
{
        int rv, index;
        struct ipmi_smi *intf;

        index = srcu_read_lock(&ipmi_interfaces_srcu);
        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
                if (intf->intf_num == if_num)
                        goto found;
        }
        srcu_read_unlock(&ipmi_interfaces_srcu, index);

        /* Not found, return an error */
        return -EINVAL;

found:
        if (!intf->handlers->get_smi_info)
                rv = -ENOTTY;
        else
                rv = intf->handlers->get_smi_info(intf->send_info, data);
        srcu_read_unlock(&ipmi_interfaces_srcu, index);

        return rv;
}
EXPORT_SYMBOL(ipmi_get_smi_info);

static void free_user(struct kref *ref)
{
        struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount);
        kfree(user);
}

static void _ipmi_destroy_user(struct ipmi_user *user)
{
        struct ipmi_smi  *intf = user->intf;
        int              i;
        unsigned long    flags;
        struct cmd_rcvr  *rcvr;
        struct cmd_rcvr  *rcvrs = NULL;

        if (!acquire_ipmi_user(user, &i)) {
                /*
                 * The user has already been cleaned up, just make sure
                 * nothing is using it and return.
                 */
                synchronize_srcu(&user->release_barrier);
                return;
        }

        rcu_assign_pointer(user->self, NULL);
        release_ipmi_user(user, i);

        synchronize_srcu(&user->release_barrier);

        if (user->handler->shutdown)
                user->handler->shutdown(user->handler_data);

        if (user->handler->ipmi_watchdog_pretimeout)
                atomic_dec(&intf->event_waiters);

        if (user->gets_events)
                atomic_dec(&intf->event_waiters);

        /* Remove the user from the interface's sequence table. */
        spin_lock_irqsave(&intf->seq_lock, flags);
        list_del_rcu(&user->link);

        for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
                if (intf->seq_table[i].inuse
                    && (intf->seq_table[i].recv_msg->user == user)) {
                        intf->seq_table[i].inuse = 0;
                        ipmi_free_recv_msg(intf->seq_table[i].recv_msg);
                }
        }
        spin_unlock_irqrestore(&intf->seq_lock, flags);

        /*
         * Remove the user from the command receiver's table.  First
         * we build a list of everything (not using the standard link,
         * since other things may be using it till we do
         * synchronize_srcu()) then free everything in that list.
         */
        mutex_lock(&intf->cmd_rcvrs_mutex);
        list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
                if (rcvr->user == user) {
                        list_del_rcu(&rcvr->link);
                        rcvr->next = rcvrs;
                        rcvrs = rcvr;
                }
        }
        mutex_unlock(&intf->cmd_rcvrs_mutex);
        synchronize_rcu();
        while (rcvrs) {
                rcvr = rcvrs;
                rcvrs = rcvr->next;
                kfree(rcvr);
        }

        kref_put(&intf->refcount, intf_free);
}

int ipmi_destroy_user(struct ipmi_user *user)
{
        _ipmi_destroy_user(user);

        cleanup_srcu_struct(&user->release_barrier);
        kref_put(&user->refcount, free_user);

        return 0;
}
EXPORT_SYMBOL(ipmi_destroy_user);

int ipmi_get_version(struct ipmi_user *user,
                     unsigned char *major,
                     unsigned char *minor)
{
        struct ipmi_device_id id;
        int rv, index;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        rv = bmc_get_device_id(user->intf, NULL, &id, NULL, NULL);
        if (!rv) {
                *major = ipmi_version_major(&id);
                *minor = ipmi_version_minor(&id);
        }
        release_ipmi_user(user, index);

        return rv;
}
EXPORT_SYMBOL(ipmi_get_version);

int ipmi_set_my_address(struct ipmi_user *user,
                        unsigned int  channel,
                        unsigned char address)
{
        int index, rv = 0;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        if (channel >= IPMI_MAX_CHANNELS)
                rv = -EINVAL;
        else
                user->intf->addrinfo[channel].address = address;
        release_ipmi_user(user, index);

        return rv;
}
EXPORT_SYMBOL(ipmi_set_my_address);

int ipmi_get_my_address(struct ipmi_user *user,
                        unsigned int  channel,
                        unsigned char *address)
{
        int index, rv = 0;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        if (channel >= IPMI_MAX_CHANNELS)
                rv = -EINVAL;
        else
                *address = user->intf->addrinfo[channel].address;
        release_ipmi_user(user, index);

        return rv;
}
EXPORT_SYMBOL(ipmi_get_my_address);

int ipmi_set_my_LUN(struct ipmi_user *user,
                    unsigned int  channel,
                    unsigned char LUN)
{
        int index, rv = 0;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        if (channel >= IPMI_MAX_CHANNELS)
                rv = -EINVAL;
        else
                user->intf->addrinfo[channel].lun = LUN & 0x3;
        release_ipmi_user(user, index);

        return 0;
}
EXPORT_SYMBOL(ipmi_set_my_LUN);

int ipmi_get_my_LUN(struct ipmi_user *user,
                    unsigned int  channel,
                    unsigned char *address)
{
        int index, rv = 0;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        if (channel >= IPMI_MAX_CHANNELS)
                rv = -EINVAL;
        else
                *address = user->intf->addrinfo[channel].lun;
        release_ipmi_user(user, index);

        return rv;
}
EXPORT_SYMBOL(ipmi_get_my_LUN);

int ipmi_get_maintenance_mode(struct ipmi_user *user)
{
        int mode, index;
        unsigned long flags;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        spin_lock_irqsave(&user->intf->maintenance_mode_lock, flags);
        mode = user->intf->maintenance_mode;
        spin_unlock_irqrestore(&user->intf->maintenance_mode_lock, flags);
        release_ipmi_user(user, index);

        return mode;
}
EXPORT_SYMBOL(ipmi_get_maintenance_mode);

static void maintenance_mode_update(struct ipmi_smi *intf)
{
        if (intf->handlers->set_maintenance_mode)
                intf->handlers->set_maintenance_mode(
                        intf->send_info, intf->maintenance_mode_enable);
}

int ipmi_set_maintenance_mode(struct ipmi_user *user, int mode)
{
        int rv = 0, index;
        unsigned long flags;
        struct ipmi_smi *intf = user->intf;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        spin_lock_irqsave(&intf->maintenance_mode_lock, flags);
        if (intf->maintenance_mode != mode) {
                switch (mode) {
                case IPMI_MAINTENANCE_MODE_AUTO:
                        intf->maintenance_mode_enable
                                = (intf->auto_maintenance_timeout > 0);
                        break;

                case IPMI_MAINTENANCE_MODE_OFF:
                        intf->maintenance_mode_enable = false;
                        break;

                case IPMI_MAINTENANCE_MODE_ON:
                        intf->maintenance_mode_enable = true;
                        break;

                default:
                        rv = -EINVAL;
                        goto out_unlock;
                }
                intf->maintenance_mode = mode;

                maintenance_mode_update(intf);
        }
 out_unlock:
        spin_unlock_irqrestore(&intf->maintenance_mode_lock, flags);
        release_ipmi_user(user, index);

        return rv;
}
EXPORT_SYMBOL(ipmi_set_maintenance_mode);

int ipmi_set_gets_events(struct ipmi_user *user, bool val)
{
        unsigned long        flags;
        struct ipmi_smi      *intf = user->intf;
        struct ipmi_recv_msg *msg, *msg2;
        struct list_head     msgs;
        int index;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        INIT_LIST_HEAD(&msgs);

        spin_lock_irqsave(&intf->events_lock, flags);
        if (user->gets_events == val)
                goto out;

        user->gets_events = val;

        if (val) {
                if (atomic_inc_return(&intf->event_waiters) == 1)
                        need_waiter(intf);
        } else {
                atomic_dec(&intf->event_waiters);
        }

        if (intf->delivering_events)
                /*
                 * Another thread is delivering events for this, so
                 * let it handle any new events.
                 */
                goto out;

        /* Deliver any queued events. */
        while (user->gets_events && !list_empty(&intf->waiting_events)) {
                list_for_each_entry_safe(msg, msg2, &intf->waiting_events, link)
                        list_move_tail(&msg->link, &msgs);
                intf->waiting_events_count = 0;
                if (intf->event_msg_printed) {
                        dev_warn(intf->si_dev,
                                 PFX "Event queue no longer full\n");
                        intf->event_msg_printed = 0;
                }

                intf->delivering_events = 1;
                spin_unlock_irqrestore(&intf->events_lock, flags);

                list_for_each_entry_safe(msg, msg2, &msgs, link) {
                        msg->user = user;
                        kref_get(&user->refcount);
                        deliver_local_response(intf, msg);
                }

                spin_lock_irqsave(&intf->events_lock, flags);
                intf->delivering_events = 0;
        }

 out:
        spin_unlock_irqrestore(&intf->events_lock, flags);
        release_ipmi_user(user, index);

        return 0;
}
EXPORT_SYMBOL(ipmi_set_gets_events);

static struct cmd_rcvr *find_cmd_rcvr(struct ipmi_smi *intf,
                                      unsigned char netfn,
                                      unsigned char cmd,
                                      unsigned char chan)
{
        struct cmd_rcvr *rcvr;

        list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
                                        && (rcvr->chans & (1 << chan)))
                        return rcvr;
        }
        return NULL;
}

static int is_cmd_rcvr_exclusive(struct ipmi_smi *intf,
                                 unsigned char netfn,
                                 unsigned char cmd,
                                 unsigned int  chans)
{
        struct cmd_rcvr *rcvr;

        list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
                                        && (rcvr->chans & chans))
                        return 0;
        }
        return 1;
}

int ipmi_register_for_cmd(struct ipmi_user *user,
                          unsigned char netfn,
                          unsigned char cmd,
                          unsigned int  chans)
{
        struct ipmi_smi *intf = user->intf;
        struct cmd_rcvr *rcvr;
        int rv = 0, index;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        rcvr = kmalloc(sizeof(*rcvr), GFP_KERNEL);
        if (!rcvr) {
                rv = -ENOMEM;
                goto out_release;
        }
        rcvr->cmd = cmd;
        rcvr->netfn = netfn;
        rcvr->chans = chans;
        rcvr->user = user;

        mutex_lock(&intf->cmd_rcvrs_mutex);
        /* Make sure the command/netfn is not already registered. */
        if (!is_cmd_rcvr_exclusive(intf, netfn, cmd, chans)) {
                rv = -EBUSY;
                goto out_unlock;
        }

        if (atomic_inc_return(&intf->event_waiters) == 1)
                need_waiter(intf);

        list_add_rcu(&rcvr->link, &intf->cmd_rcvrs);

out_unlock:
        mutex_unlock(&intf->cmd_rcvrs_mutex);
        if (rv)
                kfree(rcvr);
out_release:
        release_ipmi_user(user, index);

        return rv;
}
EXPORT_SYMBOL(ipmi_register_for_cmd);

int ipmi_unregister_for_cmd(struct ipmi_user *user,
                            unsigned char netfn,
                            unsigned char cmd,
                            unsigned int  chans)
{
        struct ipmi_smi *intf = user->intf;
        struct cmd_rcvr *rcvr;
        struct cmd_rcvr *rcvrs = NULL;
        int i, rv = -ENOENT, index;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        mutex_lock(&intf->cmd_rcvrs_mutex);
        for (i = 0; i < IPMI_NUM_CHANNELS; i++) {
                if (((1 << i) & chans) == 0)
                        continue;
                rcvr = find_cmd_rcvr(intf, netfn, cmd, i);
                if (rcvr == NULL)
                        continue;
                if (rcvr->user == user) {
                        rv = 0;
                        rcvr->chans &= ~chans;
                        if (rcvr->chans == 0) {
                                list_del_rcu(&rcvr->link);
                                rcvr->next = rcvrs;
                                rcvrs = rcvr;
                        }
                }
        }
        mutex_unlock(&intf->cmd_rcvrs_mutex);
        synchronize_rcu();
        release_ipmi_user(user, index);
        while (rcvrs) {
                atomic_dec(&intf->event_waiters);
                rcvr = rcvrs;
                rcvrs = rcvr->next;
                kfree(rcvr);
        }

        return rv;
}
EXPORT_SYMBOL(ipmi_unregister_for_cmd);

static unsigned char
ipmb_checksum(unsigned char *data, int size)
{
        unsigned char csum = 0;

        for (; size > 0; size--, data++)
                csum += *data;

        return -csum;
}

static inline void format_ipmb_msg(struct ipmi_smi_msg   *smi_msg,
                                   struct kernel_ipmi_msg *msg,
                                   struct ipmi_ipmb_addr *ipmb_addr,
                                   long                  msgid,
                                   unsigned char         ipmb_seq,
                                   int                   broadcast,
                                   unsigned char         source_address,
                                   unsigned char         source_lun)
{
        int i = broadcast;

        /* Format the IPMB header data. */
        smi_msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
        smi_msg->data[1] = IPMI_SEND_MSG_CMD;
        smi_msg->data[2] = ipmb_addr->channel;
        if (broadcast)
                smi_msg->data[3] = 0;
        smi_msg->data[i+3] = ipmb_addr->slave_addr;
        smi_msg->data[i+4] = (msg->netfn << 2) | (ipmb_addr->lun & 0x3);
        smi_msg->data[i+5] = ipmb_checksum(&smi_msg->data[i + 3], 2);
        smi_msg->data[i+6] = source_address;
        smi_msg->data[i+7] = (ipmb_seq << 2) | source_lun;
        smi_msg->data[i+8] = msg->cmd;

        /* Now tack on the data to the message. */
        if (msg->data_len > 0)
                memcpy(&smi_msg->data[i + 9], msg->data, msg->data_len);
        smi_msg->data_size = msg->data_len + 9;

        /* Now calculate the checksum and tack it on. */
        smi_msg->data[i+smi_msg->data_size]
                = ipmb_checksum(&smi_msg->data[i + 6], smi_msg->data_size - 6);

        /*
         * Add on the checksum size and the offset from the
         * broadcast.
         */
        smi_msg->data_size += 1 + i;

        smi_msg->msgid = msgid;
}

static inline void format_lan_msg(struct ipmi_smi_msg   *smi_msg,
                                  struct kernel_ipmi_msg *msg,
                                  struct ipmi_lan_addr  *lan_addr,
                                  long                  msgid,
                                  unsigned char         ipmb_seq,
                                  unsigned char         source_lun)
{
        /* Format the IPMB header data. */
        smi_msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
        smi_msg->data[1] = IPMI_SEND_MSG_CMD;
        smi_msg->data[2] = lan_addr->channel;
        smi_msg->data[3] = lan_addr->session_handle;
        smi_msg->data[4] = lan_addr->remote_SWID;
        smi_msg->data[5] = (msg->netfn << 2) | (lan_addr->lun & 0x3);
        smi_msg->data[6] = ipmb_checksum(&smi_msg->data[4], 2);
        smi_msg->data[7] = lan_addr->local_SWID;
        smi_msg->data[8] = (ipmb_seq << 2) | source_lun;
        smi_msg->data[9] = msg->cmd;

        /* Now tack on the data to the message. */
        if (msg->data_len > 0)
                memcpy(&smi_msg->data[10], msg->data, msg->data_len);
        smi_msg->data_size = msg->data_len + 10;

        /* Now calculate the checksum and tack it on. */
        smi_msg->data[smi_msg->data_size]
                = ipmb_checksum(&smi_msg->data[7], smi_msg->data_size - 7);

        /*
         * Add on the checksum size and the offset from the
         * broadcast.
         */
        smi_msg->data_size += 1;

        smi_msg->msgid = msgid;
}

static struct ipmi_smi_msg *smi_add_send_msg(struct ipmi_smi *intf,
                                             struct ipmi_smi_msg *smi_msg,
                                             int priority)
{
        if (intf->curr_msg) {
                if (priority > 0)
                        list_add_tail(&smi_msg->link, &intf->hp_xmit_msgs);
                else
                        list_add_tail(&smi_msg->link, &intf->xmit_msgs);
                smi_msg = NULL;
        } else {
                intf->curr_msg = smi_msg;
        }

        return smi_msg;
}


static void smi_send(struct ipmi_smi *intf,
                     const struct ipmi_smi_handlers *handlers,
                     struct ipmi_smi_msg *smi_msg, int priority)
{
        int run_to_completion = intf->run_to_completion;

        if (run_to_completion) {
                smi_msg = smi_add_send_msg(intf, smi_msg, priority);
        } else {
                unsigned long flags;

                spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
                smi_msg = smi_add_send_msg(intf, smi_msg, priority);
                spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
        }

        if (smi_msg)
                handlers->sender(intf->send_info, smi_msg);
}

static bool is_maintenance_mode_cmd(struct kernel_ipmi_msg *msg)
{
        return (((msg->netfn == IPMI_NETFN_APP_REQUEST)
                 && ((msg->cmd == IPMI_COLD_RESET_CMD)
                     || (msg->cmd == IPMI_WARM_RESET_CMD)))
                || (msg->netfn == IPMI_NETFN_FIRMWARE_REQUEST));
}

static int i_ipmi_req_sysintf(struct ipmi_smi        *intf,
                              struct ipmi_addr       *addr,
                              long                   msgid,
                              struct kernel_ipmi_msg *msg,
                              struct ipmi_smi_msg    *smi_msg,
                              struct ipmi_recv_msg   *recv_msg,
                              int                    retries,
                              unsigned int           retry_time_ms)
{
        struct ipmi_system_interface_addr *smi_addr;

        if (msg->netfn & 1)
                /* Responses are not allowed to the SMI. */
                return -EINVAL;

        smi_addr = (struct ipmi_system_interface_addr *) addr;
        if (smi_addr->lun > 3) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        memcpy(&recv_msg->addr, smi_addr, sizeof(*smi_addr));

        if ((msg->netfn == IPMI_NETFN_APP_REQUEST)
            && ((msg->cmd == IPMI_SEND_MSG_CMD)
                || (msg->cmd == IPMI_GET_MSG_CMD)
                || (msg->cmd == IPMI_READ_EVENT_MSG_BUFFER_CMD))) {
                /*
                 * We don't let the user do these, since we manage
                 * the sequence numbers.
                 */
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        if (is_maintenance_mode_cmd(msg)) {
                unsigned long flags;

                spin_lock_irqsave(&intf->maintenance_mode_lock, flags);
                intf->auto_maintenance_timeout
                        = maintenance_mode_timeout_ms;
                if (!intf->maintenance_mode
                    && !intf->maintenance_mode_enable) {
                        intf->maintenance_mode_enable = true;
                        maintenance_mode_update(intf);
                }
                spin_unlock_irqrestore(&intf->maintenance_mode_lock,
                                       flags);
        }

        if (msg->data_len + 2 > IPMI_MAX_MSG_LENGTH) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EMSGSIZE;
        }

        smi_msg->data[0] = (msg->netfn << 2) | (smi_addr->lun & 0x3);
        smi_msg->data[1] = msg->cmd;
        smi_msg->msgid = msgid;
        smi_msg->user_data = recv_msg;
        if (msg->data_len > 0)
                memcpy(&smi_msg->data[2], msg->data, msg->data_len);
        smi_msg->data_size = msg->data_len + 2;
        ipmi_inc_stat(intf, sent_local_commands);

        return 0;
}

static int i_ipmi_req_ipmb(struct ipmi_smi        *intf,
                           struct ipmi_addr       *addr,
                           long                   msgid,
                           struct kernel_ipmi_msg *msg,
                           struct ipmi_smi_msg    *smi_msg,
                           struct ipmi_recv_msg   *recv_msg,
                           unsigned char          source_address,
                           unsigned char          source_lun,
                           int                    retries,
                           unsigned int           retry_time_ms)
{
        struct ipmi_ipmb_addr *ipmb_addr;
        unsigned char ipmb_seq;
        long seqid;
        int broadcast = 0;
        struct ipmi_channel *chans;
        int rv = 0;

        if (addr->channel >= IPMI_MAX_CHANNELS) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        chans = READ_ONCE(intf->channel_list)->c;

        if (chans[addr->channel].medium != IPMI_CHANNEL_MEDIUM_IPMB) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        if (addr->addr_type == IPMI_IPMB_BROADCAST_ADDR_TYPE) {
                /*
                 * Broadcasts add a zero at the beginning of the
                 * message, but otherwise is the same as an IPMB
                 * address.
                 */
                addr->addr_type = IPMI_IPMB_ADDR_TYPE;
                broadcast = 1;
                retries = 0; /* Don't retry broadcasts. */
        }

        /*
         * 9 for the header and 1 for the checksum, plus
         * possibly one for the broadcast.
         */
        if ((msg->data_len + 10 + broadcast) > IPMI_MAX_MSG_LENGTH) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EMSGSIZE;
        }

        ipmb_addr = (struct ipmi_ipmb_addr *) addr;
        if (ipmb_addr->lun > 3) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        memcpy(&recv_msg->addr, ipmb_addr, sizeof(*ipmb_addr));

        if (recv_msg->msg.netfn & 0x1) {
                /*
                 * It's a response, so use the user's sequence
                 * from msgid.
                 */
                ipmi_inc_stat(intf, sent_ipmb_responses);
                format_ipmb_msg(smi_msg, msg, ipmb_addr, msgid,
                                msgid, broadcast,
                                source_address, source_lun);

                /*
                 * Save the receive message so we can use it
                 * to deliver the response.
                 */
                smi_msg->user_data = recv_msg;
        } else {
                /* It's a command, so get a sequence for it. */
                unsigned long flags;

                spin_lock_irqsave(&intf->seq_lock, flags);

                if (is_maintenance_mode_cmd(msg))
                        intf->ipmb_maintenance_mode_timeout =
                                maintenance_mode_timeout_ms;

                if (intf->ipmb_maintenance_mode_timeout && retry_time_ms == 0)
                        /* Different default in maintenance mode */
                        retry_time_ms = default_maintenance_retry_ms;

                /*
                 * Create a sequence number with a 1 second
                 * timeout and 4 retries.
                 */
                rv = intf_next_seq(intf,
                                   recv_msg,
                                   retry_time_ms,
                                   retries,
                                   broadcast,
                                   &ipmb_seq,
                                   &seqid);
                if (rv)
                        /*
                         * We have used up all the sequence numbers,
                         * probably, so abort.
                         */
                        goto out_err;

                ipmi_inc_stat(intf, sent_ipmb_commands);

                /*
                 * Store the sequence number in the message,
                 * so that when the send message response
                 * comes back we can start the timer.
                 */
                format_ipmb_msg(smi_msg, msg, ipmb_addr,
                                STORE_SEQ_IN_MSGID(ipmb_seq, seqid),
                                ipmb_seq, broadcast,
                                source_address, source_lun);

                /*
                 * Copy the message into the recv message data, so we
                 * can retransmit it later if necessary.
                 */
                memcpy(recv_msg->msg_data, smi_msg->data,
                       smi_msg->data_size);
                recv_msg->msg.data = recv_msg->msg_data;
                recv_msg->msg.data_len = smi_msg->data_size;

                /*
                 * We don't unlock until here, because we need
                 * to copy the completed message into the
                 * recv_msg before we release the lock.
                 * Otherwise, race conditions may bite us.  I
                 * know that's pretty paranoid, but I prefer
                 * to be correct.
                 */
out_err:
                spin_unlock_irqrestore(&intf->seq_lock, flags);
        }

        return rv;
}

static int i_ipmi_req_lan(struct ipmi_smi        *intf,
                          struct ipmi_addr       *addr,
                          long                   msgid,
                          struct kernel_ipmi_msg *msg,
                          struct ipmi_smi_msg    *smi_msg,
                          struct ipmi_recv_msg   *recv_msg,
                          unsigned char          source_lun,
                          int                    retries,
                          unsigned int           retry_time_ms)
{
        struct ipmi_lan_addr  *lan_addr;
        unsigned char ipmb_seq;
        long seqid;
        struct ipmi_channel *chans;
        int rv = 0;

        if (addr->channel >= IPMI_MAX_CHANNELS) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        chans = READ_ONCE(intf->channel_list)->c;

        if ((chans[addr->channel].medium
                                != IPMI_CHANNEL_MEDIUM_8023LAN)
                        && (chans[addr->channel].medium
                            != IPMI_CHANNEL_MEDIUM_ASYNC)) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        /* 11 for the header and 1 for the checksum. */
        if ((msg->data_len + 12) > IPMI_MAX_MSG_LENGTH) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EMSGSIZE;
        }

        lan_addr = (struct ipmi_lan_addr *) addr;
        if (lan_addr->lun > 3) {
                ipmi_inc_stat(intf, sent_invalid_commands);
                return -EINVAL;
        }

        memcpy(&recv_msg->addr, lan_addr, sizeof(*lan_addr));

        if (recv_msg->msg.netfn & 0x1) {
                /*
                 * It's a response, so use the user's sequence
                 * from msgid.
                 */
                ipmi_inc_stat(intf, sent_lan_responses);
                format_lan_msg(smi_msg, msg, lan_addr, msgid,
                               msgid, source_lun);

                /*
                 * Save the receive message so we can use it
                 * to deliver the response.
                 */
                smi_msg->user_data = recv_msg;
        } else {
                /* It's a command, so get a sequence for it. */
                unsigned long flags;

                spin_lock_irqsave(&intf->seq_lock, flags);

                /*
                 * Create a sequence number with a 1 second
                 * timeout and 4 retries.
                 */
                rv = intf_next_seq(intf,
                                   recv_msg,
                                   retry_time_ms,
                                   retries,
                                   0,
                                   &ipmb_seq,
                                   &seqid);
                if (rv)
                        /*
                         * We have used up all the sequence numbers,
                         * probably, so abort.
                         */
                        goto out_err;

                ipmi_inc_stat(intf, sent_lan_commands);

                /*
                 * Store the sequence number in the message,
                 * so that when the send message response
                 * comes back we can start the timer.
                 */
                format_lan_msg(smi_msg, msg, lan_addr,
                               STORE_SEQ_IN_MSGID(ipmb_seq, seqid),
                               ipmb_seq, source_lun);

                /*
                 * Copy the message into the recv message data, so we
                 * can retransmit it later if necessary.
                 */
                memcpy(recv_msg->msg_data, smi_msg->data,
                       smi_msg->data_size);
                recv_msg->msg.data = recv_msg->msg_data;
                recv_msg->msg.data_len = smi_msg->data_size;

                /*
                 * We don't unlock until here, because we need
                 * to copy the completed message into the
                 * recv_msg before we release the lock.
                 * Otherwise, race conditions may bite us.  I
                 * know that's pretty paranoid, but I prefer
                 * to be correct.
                 */
out_err:
                spin_unlock_irqrestore(&intf->seq_lock, flags);
        }

        return rv;
}

/*
 * Separate from ipmi_request so that the user does not have to be
 * supplied in certain circumstances (mainly at panic time).  If
 * messages are supplied, they will be freed, even if an error
 * occurs.
 */
static int i_ipmi_request(struct ipmi_user     *user,
                          struct ipmi_smi      *intf,
                          struct ipmi_addr     *addr,
                          long                 msgid,
                          struct kernel_ipmi_msg *msg,
                          void                 *user_msg_data,
                          void                 *supplied_smi,
                          struct ipmi_recv_msg *supplied_recv,
                          int                  priority,
                          unsigned char        source_address,
                          unsigned char        source_lun,
                          int                  retries,
                          unsigned int         retry_time_ms)
{
        struct ipmi_smi_msg *smi_msg;
        struct ipmi_recv_msg *recv_msg;
        int rv = 0;

        if (supplied_recv)
                recv_msg = supplied_recv;
        else {
                recv_msg = ipmi_alloc_recv_msg();
                if (recv_msg == NULL) {
                        rv = -ENOMEM;
                        goto out;
                }
        }
        recv_msg->user_msg_data = user_msg_data;

        if (supplied_smi)
                smi_msg = (struct ipmi_smi_msg *) supplied_smi;
        else {
                smi_msg = ipmi_alloc_smi_msg();
                if (smi_msg == NULL) {
                        ipmi_free_recv_msg(recv_msg);
                        rv = -ENOMEM;
                        goto out;
                }
        }

        rcu_read_lock();
        if (intf->in_shutdown) {
                rv = -ENODEV;
                goto out_err;
        }

        recv_msg->user = user;
        if (user)
                /* The put happens when the message is freed. */
                kref_get(&user->refcount);
        recv_msg->msgid = msgid;
        /*
         * Store the message to send in the receive message so timeout
         * responses can get the proper response data.
         */
        recv_msg->msg = *msg;

        if (addr->addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE) {
                rv = i_ipmi_req_sysintf(intf, addr, msgid, msg, smi_msg,
                                        recv_msg, retries, retry_time_ms);
        } else if (is_ipmb_addr(addr) || is_ipmb_bcast_addr(addr)) {
                rv = i_ipmi_req_ipmb(intf, addr, msgid, msg, smi_msg, recv_msg,
                                     source_address, source_lun,
                                     retries, retry_time_ms);
        } else if (is_lan_addr(addr)) {
                rv = i_ipmi_req_lan(intf, addr, msgid, msg, smi_msg, recv_msg,
                                    source_lun, retries, retry_time_ms);
        } else {
            /* Unknown address type. */
                ipmi_inc_stat(intf, sent_invalid_commands);
                rv = -EINVAL;
        }

        if (rv) {
out_err:
                ipmi_free_smi_msg(smi_msg);
                ipmi_free_recv_msg(recv_msg);
        } else {
                ipmi_debug_msg("Send", smi_msg->data, smi_msg->data_size);

                smi_send(intf, intf->handlers, smi_msg, priority);
        }
        rcu_read_unlock();

out:
        return rv;
}

static int check_addr(struct ipmi_smi  *intf,
                      struct ipmi_addr *addr,
                      unsigned char    *saddr,
                      unsigned char    *lun)
{
        if (addr->channel >= IPMI_MAX_CHANNELS)
                return -EINVAL;
        *lun = intf->addrinfo[addr->channel].lun;
        *saddr = intf->addrinfo[addr->channel].address;
        return 0;
}

int ipmi_request_settime(struct ipmi_user *user,
                         struct ipmi_addr *addr,
                         long             msgid,
                         struct kernel_ipmi_msg  *msg,
                         void             *user_msg_data,
                         int              priority,
                         int              retries,
                         unsigned int     retry_time_ms)
{
        unsigned char saddr = 0, lun = 0;
        int rv, index;

        if (!user)
                return -EINVAL;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        rv = check_addr(user->intf, addr, &saddr, &lun);
        if (!rv)
                rv = i_ipmi_request(user,
                                    user->intf,
                                    addr,
                                    msgid,
                                    msg,
                                    user_msg_data,
                                    NULL, NULL,
                                    priority,
                                    saddr,
                                    lun,
                                    retries,
                                    retry_time_ms);

        release_ipmi_user(user, index);
        return rv;
}
EXPORT_SYMBOL(ipmi_request_settime);

int ipmi_request_supply_msgs(struct ipmi_user     *user,
                             struct ipmi_addr     *addr,
                             long                 msgid,
                             struct kernel_ipmi_msg *msg,
                             void                 *user_msg_data,
                             void                 *supplied_smi,
                             struct ipmi_recv_msg *supplied_recv,
                             int                  priority)
{
        unsigned char saddr = 0, lun = 0;
        int rv, index;

        if (!user)
                return -EINVAL;

        user = acquire_ipmi_user(user, &index);
        if (!user)
                return -ENODEV;

        rv = check_addr(user->intf, addr, &saddr, &lun);
        if (!rv)
                rv = i_ipmi_request(user,
                                    user->intf,
                                    addr,
                                    msgid,
                                    msg,
                                    user_msg_data,
                                    supplied_smi,
                                    supplied_recv,
                                    priority,
                                    saddr,
                                    lun,
                                    -1, 0);

        release_ipmi_user(user, index);
        return rv;
}
EXPORT_SYMBOL(ipmi_request_supply_msgs);

static void bmc_device_id_handler(struct ipmi_smi *intf,
                                  struct ipmi_recv_msg *msg)
{
        int rv;

        if ((msg->addr.addr_type != IPMI_SYSTEM_INTERFACE_ADDR_TYPE)
                        || (msg->msg.netfn != IPMI_NETFN_APP_RESPONSE)
                        || (msg->msg.cmd != IPMI_GET_DEVICE_ID_CMD)) {
                dev_warn(intf->si_dev,
                         PFX "invalid device_id msg: addr_type=%d netfn=%x cmd=%x\n",
                        msg->addr.addr_type, msg->msg.netfn, msg->msg.cmd);
                return;
        }

        rv = ipmi_demangle_device_id(msg->msg.netfn, msg->msg.cmd,
                        msg->msg.data, msg->msg.data_len, &intf->bmc->fetch_id);
        if (rv) {
                dev_warn(intf->si_dev,
                         PFX "device id demangle failed: %d\n", rv);
                intf->bmc->dyn_id_set = 0;
        } else {
                /*
                 * Make sure the id data is available before setting
                 * dyn_id_set.
                 */
                smp_wmb();
                intf->bmc->dyn_id_set = 1;
        }

        wake_up(&intf->waitq);
}

static int
send_get_device_id_cmd(struct ipmi_smi *intf)
{
        struct ipmi_system_interface_addr si;
        struct kernel_ipmi_msg msg;

        si.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
        si.channel = IPMI_BMC_CHANNEL;
        si.lun = 0;

        msg.netfn = IPMI_NETFN_APP_REQUEST;
        msg.cmd = IPMI_GET_DEVICE_ID_CMD;
        msg.data = NULL;
        msg.data_len = 0;

        return i_ipmi_request(NULL,
                              intf,
                              (struct ipmi_addr *) &si,
                              0,
                              &msg,
                              intf,
                              NULL,
                              NULL,
                              0,
                              intf->addrinfo[0].address,
                              intf->addrinfo[0].lun,
                              -1, 0);
}

static int __get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc)
{
        int rv;

        bmc->dyn_id_set = 2;

        intf->null_user_handler = bmc_device_id_handler;

        rv = send_get_device_id_cmd(intf);
        if (rv)
                return rv;

        wait_event(intf->waitq, bmc->dyn_id_set != 2);

        if (!bmc->dyn_id_set)
                rv = -EIO; /* Something went wrong in the fetch. */

        /* dyn_id_set makes the id data available. */
        smp_rmb();

        intf->null_user_handler = NULL;

        return rv;
}

/*
 * Fetch the device id for the bmc/interface.  You must pass in either
 * bmc or intf, this code will get the other one.  If the data has
 * been recently fetched, this will just use the cached data.  Otherwise
 * it will run a new fetch.
 *
 * Except for the first time this is called (in ipmi_register_smi()),
 * this will always return good data;
 */
static int __bmc_get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc,
                               struct ipmi_device_id *id,
                               bool *guid_set, guid_t *guid, int intf_num)
{
        int rv = 0;
        int prev_dyn_id_set, prev_guid_set;
        bool intf_set = intf != NULL;

        if (!intf) {
                mutex_lock(&bmc->dyn_mutex);
retry_bmc_lock:
                if (list_empty(&bmc->intfs)) {
                        mutex_unlock(&bmc->dyn_mutex);
                        return -ENOENT;
                }
                intf = list_first_entry(&bmc->intfs, struct ipmi_smi,
                                        bmc_link);
                kref_get(&intf->refcount);
                mutex_unlock(&bmc->dyn_mutex);
                mutex_lock(&intf->bmc_reg_mutex);
                mutex_lock(&bmc->dyn_mutex);
                if (intf != list_first_entry(&bmc->intfs, struct ipmi_smi,
                                             bmc_link)) {
                        mutex_unlock(&intf->bmc_reg_mutex);
                        kref_put(&intf->refcount, intf_free);
                        goto retry_bmc_lock;
                }
        } else {
                mutex_lock(&intf->bmc_reg_mutex);
                bmc = intf->bmc;
                mutex_lock(&bmc->dyn_mutex);
                kref_get(&intf->refcount);
        }

        /* If we have a valid and current ID, just return that. */
        if (intf->in_bmc_register ||
            (bmc->dyn_id_set && time_is_after_jiffies(bmc->dyn_id_expiry)))
                goto out_noprocessing;

        prev_guid_set = bmc->dyn_guid_set;
        __get_guid(intf);

        prev_dyn_id_set = bmc->dyn_id_set;
        rv = __get_device_id(intf, bmc);
        if (rv)
                goto out;

        /*
         * The guid, device id, manufacturer id, and product id should
         * not change on a BMC.  If it does we have to do some dancing.
         */
        if (!intf->bmc_registered
            || (!prev_guid_set && bmc->dyn_guid_set)
            || (!prev_dyn_id_set && bmc->dyn_id_set)
            || (prev_guid_set && bmc->dyn_guid_set
                && !guid_equal(&bmc->guid, &bmc->fetch_guid))
            || bmc->id.device_id != bmc->fetch_id.device_id
            || bmc->id.manufacturer_id != bmc->fetch_id.manufacturer_id
            || bmc->id.product_id != bmc->fetch_id.product_id) {
                struct ipmi_device_id id = bmc->fetch_id;
                int guid_set = bmc->dyn_guid_set;
                guid_t guid;

                guid = bmc->fetch_guid;
                mutex_unlock(&bmc->dyn_mutex);

                __ipmi_bmc_unregister(intf);
                /* Fill in the temporary BMC for good measure. */
                intf->bmc->id = id;
                intf->bmc->dyn_guid_set = guid_set;
                intf->bmc->guid = guid;
                if (__ipmi_bmc_register(intf, &id, guid_set, &guid, intf_num))
                        need_waiter(intf); /* Retry later on an error. */
                else
                        __scan_channels(intf, &id);


                if (!intf_set) {
                        /*
                         * We weren't given the interface on the
                         * command line, so restart the operation on
                         * the next interface for the BMC.
                         */
                        mutex_unlock(&intf->bmc_reg_mutex);
                        mutex_lock(&bmc->dyn_mutex);
                        goto retry_bmc_lock;
                }

                /* We have a new BMC, set it up. */
                bmc = intf->bmc;
                mutex_lock(&bmc->dyn_mutex);
                goto out_noprocessing;
        } else if (memcmp(&bmc->fetch_id, &bmc->id, sizeof(bmc->id)))
                /* Version info changes, scan the channels again. */
                __scan_channels(intf, &bmc->fetch_id);

        bmc->dyn_id_expiry = jiffies + IPMI_DYN_DEV_ID_EXPIRY;

out:
        if (rv && prev_dyn_id_set) {
                rv = 0; /* Ignore failures if we have previous data. */
                bmc->dyn_id_set = prev_dyn_id_set;
        }
        if (!rv) {
                bmc->id = bmc->fetch_id;
                if (bmc->dyn_guid_set)
                        bmc->guid = bmc->fetch_guid;
                else if (prev_guid_set)
                        /*
                         * The guid used to be valid and it failed to fetch,
                         * just use the cached value.
                         */
                        bmc->dyn_guid_set = prev_guid_set;
        }
out_noprocessing:
        if (!rv) {
                if (id)
                        *id = bmc->id;

                if (guid_set)
                        *guid_set = bmc->dyn_guid_set;

                if (guid && bmc->dyn_guid_set)
                        *guid =  bmc->guid;
        }

        mutex_unlock(&bmc->dyn_mutex);
        mutex_unlock(&intf->bmc_reg_mutex);

        kref_put(&intf->refcount, intf_free);
        return rv;
}

static int bmc_get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc,
                             struct ipmi_device_id *id,
                             bool *guid_set, guid_t *guid)
{
        return __bmc_get_device_id(intf, bmc, id, guid_set, guid, -1);
}

static ssize_t device_id_show(struct device *dev,
                              struct device_attribute *attr,
                              char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 10, "%u\n", id.device_id);
}
static DEVICE_ATTR_RO(device_id);

static ssize_t provides_device_sdrs_show(struct device *dev,
                                         struct device_attribute *attr,
                                         char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 10, "%u\n", (id.device_revision & 0x80) >> 7);
}
static DEVICE_ATTR_RO(provides_device_sdrs);

static ssize_t revision_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 20, "%u\n", id.device_revision & 0x0F);
}
static DEVICE_ATTR_RO(revision);

static ssize_t firmware_revision_show(struct device *dev,
                                      struct device_attribute *attr,
                                      char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 20, "%u.%x\n", id.firmware_revision_1,
                        id.firmware_revision_2);
}
static DEVICE_ATTR_RO(firmware_revision);

static ssize_t ipmi_version_show(struct device *dev,
                                 struct device_attribute *attr,
                                 char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 20, "%u.%u\n",
                        ipmi_version_major(&id),
                        ipmi_version_minor(&id));
}
static DEVICE_ATTR_RO(ipmi_version);

static ssize_t add_dev_support_show(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 10, "0x%02x\n", id.additional_device_support);
}
static DEVICE_ATTR(additional_device_support, S_IRUGO, add_dev_support_show,
                   NULL);

static ssize_t manufacturer_id_show(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 20, "0x%6.6x\n", id.manufacturer_id);
}
static DEVICE_ATTR_RO(manufacturer_id);

static ssize_t product_id_show(struct device *dev,
                               struct device_attribute *attr,
                               char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 10, "0x%4.4x\n", id.product_id);
}
static DEVICE_ATTR_RO(product_id);

static ssize_t aux_firmware_rev_show(struct device *dev,
                                     struct device_attribute *attr,
                                     char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        struct ipmi_device_id id;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
        if (rv)
                return rv;

        return snprintf(buf, 21, "0x%02x 0x%02x 0x%02x 0x%02x\n",
                        id.aux_firmware_revision[3],
                        id.aux_firmware_revision[2],
                        id.aux_firmware_revision[1],
                        id.aux_firmware_revision[0]);
}
static DEVICE_ATTR(aux_firmware_revision, S_IRUGO, aux_firmware_rev_show, NULL);

static ssize_t guid_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct bmc_device *bmc = to_bmc_device(dev);
        bool guid_set;
        guid_t guid;
        int rv;

        rv = bmc_get_device_id(NULL, bmc, NULL, &guid_set, &guid);
        if (rv)
                return rv;
        if (!guid_set)
                return -ENOENT;

        return snprintf(buf, 38, "%pUl\n", guid.b);
}
static DEVICE_ATTR_RO(guid);

static struct attribute *bmc_dev_attrs[] = {
        &dev_attr_device_id.attr,
        &dev_attr_provides_device_sdrs.attr,
        &dev_attr_revision.attr,
        &dev_attr_firmware_revision.attr,
        &dev_attr_ipmi_version.attr,
        &dev_attr_additional_device_support.attr,
        &dev_attr_manufacturer_id.attr,
        &dev_attr_product_id.attr,
        &dev_attr_aux_firmware_revision.attr,
        &dev_attr_guid.attr,
        NULL
};

static umode_t bmc_dev_attr_is_visible(struct kobject *kobj,
                                       struct attribute *attr, int idx)
{
        struct device *dev = kobj_to_dev(kobj);
        struct bmc_device *bmc = to_bmc_device(dev);
        umode_t mode = attr->mode;
        int rv;

        if (attr == &dev_attr_aux_firmware_revision.attr) {
                struct ipmi_device_id id;

                rv = bmc_get_device_id(NULL, bmc, &id, NULL, NULL);
                return (!rv && id.aux_firmware_revision_set) ? mode : 0;
        }
        if (attr == &dev_attr_guid.attr) {
                bool guid_set;

                rv = bmc_get_device_id(NULL, bmc, NULL, &guid_set, NULL);
                return (!rv && guid_set) ? mode : 0;
        }
        return mode;
}

static const struct attribute_group bmc_dev_attr_group = {
        .attrs          = bmc_dev_attrs,
        .is_visible     = bmc_dev_attr_is_visible,
};

static const struct attribute_group *bmc_dev_attr_groups[] = {
        &bmc_dev_attr_group,
        NULL
};

static const struct device_type bmc_device_type = {
        .groups         = bmc_dev_attr_groups,
};

static int __find_bmc_guid(struct device *dev, void *data)
{
        guid_t *guid = data;
        struct bmc_device *bmc;
        int rv;

        if (dev->type != &bmc_device_type)
                return 0;

        bmc = to_bmc_device(dev);
        rv = bmc->dyn_guid_set && guid_equal(&bmc->guid, guid);
        if (rv)
                rv = kref_get_unless_zero(&bmc->usecount);
        return rv;
}

/*
 * Returns with the bmc's usecount incremented, if it is non-NULL.
 */
static struct bmc_device *ipmi_find_bmc_guid(struct device_driver *drv,
                                             guid_t *guid)
{
        struct device *dev;
        struct bmc_device *bmc = NULL;

        dev = driver_find_device(drv, NULL, guid, __find_bmc_guid);
        if (dev) {
                bmc = to_bmc_device(dev);
                put_device(dev);
        }
        return bmc;
}

struct prod_dev_id {
        unsigned int  product_id;
        unsigned char device_id;
};

static int __find_bmc_prod_dev_id(struct device *dev, void *data)
{
        struct prod_dev_id *cid = data;
        struct bmc_device *bmc;
        int rv;

        if (dev->type != &bmc_device_type)
                return 0;

        bmc = to_bmc_device(dev);
        rv = (bmc->id.product_id == cid->product_id
              && bmc->id.device_id == cid->device_id);
        if (rv)
                rv = kref_get_unless_zero(&bmc->usecount);
        return rv;
}

/*
 * Returns with the bmc's usecount incremented, if it is non-NULL.
 */
static struct bmc_device *ipmi_find_bmc_prod_dev_id(
        struct device_driver *drv,
        unsigned int product_id, unsigned char device_id)
{
        struct prod_dev_id id = {
                .product_id = product_id,
                .device_id = device_id,
        };
        struct device *dev;
        struct bmc_device *bmc = NULL;

        dev = driver_find_device(drv, NULL, &id, __find_bmc_prod_dev_id);
        if (dev) {
                bmc = to_bmc_device(dev);
                put_device(dev);
        }
        return bmc;
}

static DEFINE_IDA(ipmi_bmc_ida);

static void
release_bmc_device(struct device *dev)
{
        kfree(to_bmc_device(dev));
}

static void cleanup_bmc_work(struct work_struct *work)
{
        struct bmc_device *bmc = container_of(work, struct bmc_device,
                                              remove_work);
        int id = bmc->pdev.id; /* Unregister overwrites id */

        platform_device_unregister(&bmc->pdev);
        ida_simple_remove(&ipmi_bmc_ida, id);
}

static void
cleanup_bmc_device(struct kref *ref)
{
        struct bmc_device *bmc = container_of(ref, struct bmc_device, usecount);

        /*
         * Remove the platform device in a work queue to avoid issues
         * with removing the device attributes while reading a device
         * attribute.
         */
        schedule_work(&bmc->remove_work);
}

/*
 * Must be called with intf->bmc_reg_mutex held.
 */
static void __ipmi_bmc_unregister(struct ipmi_smi *intf)
{
        struct bmc_device *bmc = intf->bmc;

        if (!intf->bmc_registered)
                return;

        sysfs_remove_link(&intf->si_dev->kobj, "bmc");
        sysfs_remove_link(&bmc->pdev.dev.kobj, intf->my_dev_name);
        kfree(intf->my_dev_name);
        intf->my_dev_name = NULL;

        mutex_lock(&bmc->dyn_mutex);
        list_del(&intf->bmc_link);
        mutex_unlock(&bmc->dyn_mutex);
        intf->bmc = &intf->tmp_bmc;
        kref_put(&bmc->usecount, cleanup_bmc_device);
        intf->bmc_registered = false;
}

static void ipmi_bmc_unregister(struct ipmi_smi *intf)
{
        mutex_lock(&intf->bmc_reg_mutex);
        __ipmi_bmc_unregister(intf);
        mutex_unlock(&intf->bmc_reg_mutex);
}

/*
 * Must be called with intf->bmc_reg_mutex held.
 */
static int __ipmi_bmc_register(struct ipmi_smi *intf,
                               struct ipmi_device_id *id,
                               bool guid_set, guid_t *guid, int intf_num)
{
        int               rv;
        struct bmc_device *bmc;
        struct bmc_device *old_bmc;

        /*
         * platform_device_register() can cause bmc_reg_mutex to
         * be claimed because of the is_visible functions of
         * the attributes.  Eliminate possible recursion and
         * release the lock.
         */
        intf->in_bmc_register = true;
        mutex_unlock(&intf->bmc_reg_mutex);

        /*
         * Try to find if there is an bmc_device struct
         * representing the interfaced BMC already
         */
        mutex_lock(&ipmidriver_mutex);
        if (guid_set)
                old_bmc = ipmi_find_bmc_guid(&ipmidriver.driver, guid);
        else
                old_bmc = ipmi_find_bmc_prod_dev_id(&ipmidriver.driver,
                                                    id->product_id,
                                                    id->device_id);

        /*
         * If there is already an bmc_device, free the new one,
         * otherwise register the new BMC device
         */
        if (old_bmc) {
                bmc = old_bmc;
                /*
                 * Note: old_bmc already has usecount incremented by
                 * the BMC find functions.
                 */
                intf->bmc = old_bmc;
                mutex_lock(&bmc->dyn_mutex);
                list_add_tail(&intf->bmc_link, &bmc->intfs);
                mutex_unlock(&bmc->dyn_mutex);

                dev_info(intf->si_dev,
                         "ipmi: interfacing existing BMC (man_id: 0x%6.6x,"
                         " prod_id: 0x%4.4x, dev_id: 0x%2.2x)\n",
                         bmc->id.manufacturer_id,
                         bmc->id.product_id,
                         bmc->id.device_id);
        } else {
                bmc = kzalloc(sizeof(*bmc), GFP_KERNEL);
                if (!bmc) {
                        rv = -ENOMEM;
                        goto out;
                }
                INIT_LIST_HEAD(&bmc->intfs);
                mutex_init(&bmc->dyn_mutex);
                INIT_WORK(&bmc->remove_work, cleanup_bmc_work);

                bmc->id = *id;
                bmc->dyn_id_set = 1;
                bmc->dyn_guid_set = guid_set;
                bmc->guid = *guid;
                bmc->dyn_id_expiry = jiffies + IPMI_DYN_DEV_ID_EXPIRY;

                bmc->pdev.name = "ipmi_bmc";

                rv = ida_simple_get(&ipmi_bmc_ida, 0, 0, GFP_KERNEL);
                if (rv < 0)
                        goto out;
                bmc->pdev.dev.driver = &ipmidriver.driver;
                bmc->pdev.id = rv;
                bmc->pdev.dev.release = release_bmc_device;
                bmc->pdev.dev.type = &bmc_device_type;
                kref_init(&bmc->usecount);

                intf->bmc = bmc;
                mutex_lock(&bmc->dyn_mutex);
                list_add_tail(&intf->bmc_link, &bmc->intfs);
                mutex_unlock(&bmc->dyn_mutex);

                rv = platform_device_register(&bmc->pdev);
                if (rv) {
                        dev_err(intf->si_dev,
                                PFX " Unable to register bmc device: %d\n",
                                rv);
                        goto out_list_del;
                }

                dev_info(intf->si_dev,
                         "Found new BMC (man_id: 0x%6.6x, prod_id: 0x%4.4x, dev_id: 0x%2.2x)\n",
                         bmc->id.manufacturer_id,
                         bmc->id.product_id,
                         bmc->id.device_id);
        }

        /*
         * create symlink from system interface device to bmc device
         * and back.
         */
        rv = sysfs_create_link(&intf->si_dev->kobj, &bmc->pdev.dev.kobj, "bmc");
        if (rv) {
                dev_err(intf->si_dev,
                        PFX "Unable to create bmc symlink: %d\n", rv);
                goto out_put_bmc;
        }

        if (intf_num == -1)
                intf_num = intf->intf_num;
        intf->my_dev_name = kasprintf(GFP_KERNEL, "ipmi%d", intf_num);
        if (!intf->my_dev_name) {
                rv = -ENOMEM;
                dev_err(intf->si_dev,
                        PFX "Unable to allocate link from BMC: %d\n", rv);
                goto out_unlink1;
        }

        rv = sysfs_create_link(&bmc->pdev.dev.kobj, &intf->si_dev->kobj,
                               intf->my_dev_name);
        if (rv) {
                kfree(intf->my_dev_name);
                intf->my_dev_name = NULL;
                dev_err(intf->si_dev,
                        PFX "Unable to create symlink to bmc: %d\n", rv);
                goto out_free_my_dev_name;
        }

        intf->bmc_registered = true;

out:
        mutex_unlock(&ipmidriver_mutex);
        mutex_lock(&intf->bmc_reg_mutex);
        intf->in_bmc_register = false;
        return rv;


out_free_my_dev_name:
        kfree(intf->my_dev_name);
        intf->my_dev_name = NULL;

out_unlink1:
        sysfs_remove_link(&intf->si_dev->kobj, "bmc");

out_put_bmc:
        mutex_lock(&bmc->dyn_mutex);
        list_del(&intf->bmc_link);
        mutex_unlock(&bmc->dyn_mutex);
        intf->bmc = &intf->tmp_bmc;
        kref_put(&bmc->usecount, cleanup_bmc_device);
        goto out;

out_list_del:
        mutex_lock(&bmc->dyn_mutex);
        list_del(&intf->bmc_link);
        mutex_unlock(&bmc->dyn_mutex);
        intf->bmc = &intf->tmp_bmc;
        put_device(&bmc->pdev.dev);
        goto out;
}

static int
send_guid_cmd(struct ipmi_smi *intf, int chan)
{
        struct kernel_ipmi_msg            msg;
        struct ipmi_system_interface_addr si;

        si.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
        si.channel = IPMI_BMC_CHANNEL;
        si.lun = 0;

        msg.netfn = IPMI_NETFN_APP_REQUEST;
        msg.cmd = IPMI_GET_DEVICE_GUID_CMD;
        msg.data = NULL;
        msg.data_len = 0;
        return i_ipmi_request(NULL,
                              intf,
                              (struct ipmi_addr *) &si,
                              0,
                              &msg,
                              intf,
                              NULL,
                              NULL,
                              0,
                              intf->addrinfo[0].address,
                              intf->addrinfo[0].lun,
                              -1, 0);
}

static void guid_handler(struct ipmi_smi *intf, struct ipmi_recv_msg *msg)
{
        struct bmc_device *bmc = intf->bmc;

        if ((msg->addr.addr_type != IPMI_SYSTEM_INTERFACE_ADDR_TYPE)
            || (msg->msg.netfn != IPMI_NETFN_APP_RESPONSE)
            || (msg->msg.cmd != IPMI_GET_DEVICE_GUID_CMD))
                /* Not for me */
                return;

        if (msg->msg.data[0] != 0) {
                /* Error from getting the GUID, the BMC doesn't have one. */
                bmc->dyn_guid_set = 0;
                goto out;
        }

        if (msg->msg.data_len < 17) {
                bmc->dyn_guid_set = 0;
                dev_warn(intf->si_dev,
                         PFX "The GUID response from the BMC was too short, it was %d but should have been 17.  Assuming GUID is not available.\n",
                         msg->msg.data_len);
                goto out;
        }

        memcpy(bmc->fetch_guid.b, msg->msg.data + 1, 16);
        /*
         * Make sure the guid data is available before setting
         * dyn_guid_set.
         */
        smp_wmb();
        bmc->dyn_guid_set = 1;
 out:
        wake_up(&intf->waitq);
}

static void __get_guid(struct ipmi_smi *intf)
{
        int rv;
        struct bmc_device *bmc = intf->bmc;

        bmc->dyn_guid_set = 2;
        intf->null_user_handler = guid_handler;
        rv = send_guid_cmd(intf, 0);
        if (rv)
                /* Send failed, no GUID available. */
                bmc->dyn_guid_set = 0;

        wait_event(intf->waitq, bmc->dyn_guid_set != 2);

        /* dyn_guid_set makes the guid data available. */
        smp_rmb();

        intf->null_user_handler = NULL;
}

static int
send_channel_info_cmd(struct ipmi_smi *intf, int chan)
{
        struct kernel_ipmi_msg            msg;
        unsigned char                     data[1];
        struct ipmi_system_interface_addr si;

        si.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
        si.channel = IPMI_BMC_CHANNEL;
        si.lun = 0;

        msg.netfn = IPMI_NETFN_APP_REQUEST;
        msg.cmd = IPMI_GET_CHANNEL_INFO_CMD;
        msg.data = data;
        msg.data_len = 1;
        data[0] = chan;
        return i_ipmi_request(NULL,
                              intf,
                              (struct ipmi_addr *) &si,
                              0,
                              &msg,
                              intf,
                              NULL,
                              NULL,
                              0,
                              intf->addrinfo[0].address,
                              intf->addrinfo[0].lun,
                              -1, 0);
}

static void
channel_handler(struct ipmi_smi *intf, struct ipmi_recv_msg *msg)
{
        int rv = 0;
        int ch;
        unsigned int set = intf->curr_working_cset;
        struct ipmi_channel *chans;

        if ((msg->addr.addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE)
            && (msg->msg.netfn == IPMI_NETFN_APP_RESPONSE)
            && (msg->msg.cmd == IPMI_GET_CHANNEL_INFO_CMD)) {
                /* It's the one we want */
                if (msg->msg.data[0] != 0) {
                        /* Got an error from the channel, just go on. */

                        if (msg->msg.data[0] == IPMI_INVALID_COMMAND_ERR) {
                                /*
                                 * If the MC does not support this
                                 * command, that is legal.  We just
                                 * assume it has one IPMB at channel
                                 * zero.
                                 */
                                intf->wchannels[set].c[0].medium
                                        = IPMI_CHANNEL_MEDIUM_IPMB;
                                intf->wchannels[set].c[0].protocol
                                        = IPMI_CHANNEL_PROTOCOL_IPMB;

                                intf->channel_list = intf->wchannels + set;
                                intf->channels_ready = true;
                                wake_up(&intf->waitq);
                                goto out;
                        }
                        goto next_channel;
                }
                if (msg->msg.data_len < 4) {
                        /* Message not big enough, just go on. */
                        goto next_channel;
                }
                ch = intf->curr_channel;
                chans = intf->wchannels[set].c;
                chans[ch].medium = msg->msg.data[2] & 0x7f;
                chans[ch].protocol = msg->msg.data[3] & 0x1f;

 next_channel:
                intf->curr_channel++;
                if (intf->curr_channel >= IPMI_MAX_CHANNELS) {
                        intf->channel_list = intf->wchannels + set;
                        intf->channels_ready = true;
                        wake_up(&intf->waitq);
                } else {
                        intf->channel_list = intf->wchannels + set;
                        intf->channels_ready = true;
                        rv = send_channel_info_cmd(intf, intf->curr_channel);
                }

                if (rv) {
                        /* Got an error somehow, just give up. */
                        dev_warn(intf->si_dev,
                                 PFX "Error sending channel information for channel %d: %d\n",
                                 intf->curr_channel, rv);

                        intf->channel_list = intf->wchannels + set;
                        intf->channels_ready = true;
                        wake_up(&intf->waitq);
                }
        }
 out:
        return;
}

/*
 * Must be holding intf->bmc_reg_mutex to call this.
 */
static int __scan_channels(struct ipmi_smi *intf, struct ipmi_device_id *id)
{
        int rv;

        if (ipmi_version_major(id) > 1
                        || (ipmi_version_major(id) == 1
                            && ipmi_version_minor(id) >= 5)) {
                unsigned int set;

                /*
                 * Start scanning the channels to see what is
                 * available.
                 */
                set = !intf->curr_working_cset;
                intf->curr_working_cset = set;
                memset(&intf->wchannels[set], 0,
                       sizeof(struct ipmi_channel_set));

                intf->null_user_handler = channel_handler;
                intf->curr_channel = 0;
                rv = send_channel_info_cmd(intf, 0);
                if (rv) {
                        dev_warn(intf->si_dev,
                                 "Error sending channel information for channel 0, %d\n",
                                 rv);
                        return -EIO;
                }

                /* Wait for the channel info to be read. */
                wait_event(intf->waitq, intf->channels_ready);
                intf->null_user_handler = NULL;
        } else {
                unsigned int set = intf->curr_working_cset;

                /* Assume a single IPMB channel at zero. */
                intf->wchannels[set].c[0].medium = IPMI_CHANNEL_MEDIUM_IPMB;
                intf->wchannels[set].c[0].protocol = IPMI_CHANNEL_PROTOCOL_IPMB;
                intf->channel_list = intf->wchannels + set;
                intf->channels_ready = true;
        }

        return 0;
}

static void ipmi_poll(struct ipmi_smi *intf)
{
        if (intf->handlers->poll)
                intf->handlers->poll(intf->send_info);
        /* In case something came in */
        handle_new_recv_msgs(intf);
}

void ipmi_poll_interface(struct ipmi_user *user)
{
        ipmi_poll(user->intf);
}
EXPORT_SYMBOL(ipmi_poll_interface);

static void redo_bmc_reg(struct work_struct *work)
{
        struct ipmi_smi *intf = container_of(work, struct ipmi_smi,
                                             bmc_reg_work);

        if (!intf->in_shutdown)
                bmc_get_device_id(intf, NULL, NULL, NULL, NULL);

        kref_put(&intf->refcount, intf_free);
}

int ipmi_register_smi(const struct ipmi_smi_handlers *handlers,
                      void                     *send_info,
                      struct device            *si_dev,
                      unsigned char            slave_addr)
{
        int              i, j;
        int              rv;
        struct ipmi_smi *intf, *tintf;
        struct list_head *link;
        struct ipmi_device_id id;

        /*
         * Make sure the driver is actually initialized, this handles
         * problems with initialization order.
         */
        if (!initialized) {
                rv = ipmi_init_msghandler();
                if (rv)
                        return rv;
                /*
                 * The init code doesn't return an error if it was turned
                 * off, but it won't initialize.  Check that.
                 */
                if (!initialized)
                        return -ENODEV;
        }

        intf = kzalloc(sizeof(*intf), GFP_KERNEL);
        if (!intf)
                return -ENOMEM;

        rv = init_srcu_struct(&intf->users_srcu);
        if (rv) {
                kfree(intf);
                return rv;
        }


        intf->bmc = &intf->tmp_bmc;
        INIT_LIST_HEAD(&intf->bmc->intfs);
        mutex_init(&intf->bmc->dyn_mutex);
        INIT_LIST_HEAD(&intf->bmc_link);
        mutex_init(&intf->bmc_reg_mutex);
        intf->intf_num = -1; /* Mark it invalid for now. */
        kref_init(&intf->refcount);
        INIT_WORK(&intf->bmc_reg_work, redo_bmc_reg);
        intf->si_dev = si_dev;
        for (j = 0; j < IPMI_MAX_CHANNELS; j++) {
                intf->addrinfo[j].address = IPMI_BMC_SLAVE_ADDR;
                intf->addrinfo[j].lun = 2;
        }
        if (slave_addr != 0)
                intf->addrinfo[0].address = slave_addr;
        INIT_LIST_HEAD(&intf->users);
        intf->handlers = handlers;
        intf->send_info = send_info;
        spin_lock_init(&intf->seq_lock);
        for (j = 0; j < IPMI_IPMB_NUM_SEQ; j++) {
                intf->seq_table[j].inuse = 0;
                intf->seq_table[j].seqid = 0;
        }
        intf->curr_seq = 0;
        spin_lock_init(&intf->waiting_rcv_msgs_lock);
        INIT_LIST_HEAD(&intf->waiting_rcv_msgs);
        tasklet_init(&intf->recv_tasklet,
                     smi_recv_tasklet,
                     (unsigned long) intf);
        atomic_set(&intf->watchdog_pretimeouts_to_deliver, 0);
        spin_lock_init(&intf->xmit_msgs_lock);
        INIT_LIST_HEAD(&intf->xmit_msgs);
        INIT_LIST_HEAD(&intf->hp_xmit_msgs);
        spin_lock_init(&intf->events_lock);
        atomic_set(&intf->event_waiters, 0);
        intf->ticks_to_req_ev = IPMI_REQUEST_EV_TIME;
        INIT_LIST_HEAD(&intf->waiting_events);
        intf->waiting_events_count = 0;
        mutex_init(&intf->cmd_rcvrs_mutex);
        spin_lock_init(&intf->maintenance_mode_lock);
        INIT_LIST_HEAD(&intf->cmd_rcvrs);
        init_waitqueue_head(&intf->waitq);
        for (i = 0; i < IPMI_NUM_STATS; i++)
                atomic_set(&intf->stats[i], 0);

        mutex_lock(&ipmi_interfaces_mutex);
        /* Look for a hole in the numbers. */
        i = 0;
        link = &ipmi_interfaces;
        list_for_each_entry_rcu(tintf, &ipmi_interfaces, link) {
                if (tintf->intf_num != i) {
                        link = &tintf->link;
                        break;
                }
                i++;
        }
        /* Add the new interface in numeric order. */
        if (i == 0)
                list_add_rcu(&intf->link, &ipmi_interfaces);
        else
                list_add_tail_rcu(&intf->link, link);

        rv = handlers->start_processing(send_info, intf);
        if (rv)
                goto out_err;

        rv = __bmc_get_device_id(intf, NULL, &id, NULL, NULL, i);
        if (rv) {
                dev_err(si_dev, "Unable to get the device id: %d\n", rv);
                goto out_err_started;
        }

        mutex_lock(&intf->bmc_reg_mutex);
        rv = __scan_channels(intf, &id);
        mutex_unlock(&intf->bmc_reg_mutex);
        if (rv)
                goto out_err_bmc_reg;

        /*
         * Keep memory order straight for RCU readers.  Make
         * sure everything else is committed to memory before
         * setting intf_num to mark the interface valid.
         */
        smp_wmb();
        intf->intf_num = i;
        mutex_unlock(&ipmi_interfaces_mutex);

        /* After this point the interface is legal to use. */
        call_smi_watchers(i, intf->si_dev);

        return 0;

 out_err_bmc_reg:
        ipmi_bmc_unregister(intf);
 out_err_started:
        if (intf->handlers->shutdown)
                intf->handlers->shutdown(intf->send_info);
 out_err:
        list_del_rcu(&intf->link);
        mutex_unlock(&ipmi_interfaces_mutex);
        synchronize_srcu(&ipmi_interfaces_srcu);
        cleanup_srcu_struct(&intf->users_srcu);
        kref_put(&intf->refcount, intf_free);

        return rv;
}
EXPORT_SYMBOL(ipmi_register_smi);

static void deliver_smi_err_response(struct ipmi_smi *intf,
                                     struct ipmi_smi_msg *msg,
                                     unsigned char err)
{
        msg->rsp[0] = msg->data[0] | 4;
        msg->rsp[1] = msg->data[1];
        msg->rsp[2] = err;
        msg->rsp_size = 3;
        /* It's an error, so it will never requeue, no need to check return. */
        handle_one_recv_msg(intf, msg);
}

static void cleanup_smi_msgs(struct ipmi_smi *intf)
{
        int              i;
        struct seq_table *ent;
        struct ipmi_smi_msg *msg;
        struct list_head *entry;
        struct list_head tmplist;

        /* Clear out our transmit queues and hold the messages. */
        INIT_LIST_HEAD(&tmplist);
        list_splice_tail(&intf->hp_xmit_msgs, &tmplist);
        list_splice_tail(&intf->xmit_msgs, &tmplist);

        /* Current message first, to preserve order */
        while (intf->curr_msg && !list_empty(&intf->waiting_rcv_msgs)) {
                /* Wait for the message to clear out. */
                schedule_timeout(1);
        }

        /* No need for locks, the interface is down. */

        /*
         * Return errors for all pending messages in queue and in the
         * tables waiting for remote responses.
         */
        while (!list_empty(&tmplist)) {
                entry = tmplist.next;
                list_del(entry);
                msg = list_entry(entry, struct ipmi_smi_msg, link);
                deliver_smi_err_response(intf, msg, IPMI_ERR_UNSPECIFIED);
        }

        for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
                ent = &intf->seq_table[i];
                if (!ent->inuse)
                        continue;
                deliver_err_response(intf, ent->recv_msg, IPMI_ERR_UNSPECIFIED);
        }
}

void ipmi_unregister_smi(struct ipmi_smi *intf)
{
        struct ipmi_smi_watcher *w;
        int intf_num = intf->intf_num, index;

        mutex_lock(&ipmi_interfaces_mutex);
        intf->intf_num = -1;
        intf->in_shutdown = true;
        list_del_rcu(&intf->link);
        mutex_unlock(&ipmi_interfaces_mutex);
        synchronize_srcu(&ipmi_interfaces_srcu);

        /* At this point no users can be added to the interface. */

        /*
         * Call all the watcher interfaces to tell them that
         * an interface is going away.
         */
        mutex_lock(&smi_watchers_mutex);
        list_for_each_entry(w, &smi_watchers, link)
                w->smi_gone(intf_num);
        mutex_unlock(&smi_watchers_mutex);

        index = srcu_read_lock(&intf->users_srcu);
        while (!list_empty(&intf->users)) {
                struct ipmi_user *user =
                        container_of(list_next_rcu(&intf->users),
                                     struct ipmi_user, link);

                _ipmi_destroy_user(user);
        }
        srcu_read_unlock(&intf->users_srcu, index);

        if (intf->handlers->shutdown)
                intf->handlers->shutdown(intf->send_info);

        cleanup_smi_msgs(intf);

        ipmi_bmc_unregister(intf);

        cleanup_srcu_struct(&intf->users_srcu);
        kref_put(&intf->refcount, intf_free);
}
EXPORT_SYMBOL(ipmi_unregister_smi);

static int handle_ipmb_get_msg_rsp(struct ipmi_smi *intf,
                                   struct ipmi_smi_msg *msg)
{
        struct ipmi_ipmb_addr ipmb_addr;
        struct ipmi_recv_msg  *recv_msg;

        /*
         * This is 11, not 10, because the response must contain a
         * completion code.
         */
        if (msg->rsp_size < 11) {
                /* Message not big enough, just ignore it. */
                ipmi_inc_stat(intf, invalid_ipmb_responses);
                return 0;
        }

        if (msg->rsp[2] != 0) {
                /* An error getting the response, just ignore it. */
                return 0;
        }

        ipmb_addr.addr_type = IPMI_IPMB_ADDR_TYPE;
        ipmb_addr.slave_addr = msg->rsp[6];
        ipmb_addr.channel = msg->rsp[3] & 0x0f;
        ipmb_addr.lun = msg->rsp[7] & 3;

        /*
         * It's a response from a remote entity.  Look up the sequence
         * number and handle the response.
         */
        if (intf_find_seq(intf,
                          msg->rsp[7] >> 2,
                          msg->rsp[3] & 0x0f,
                          msg->rsp[8],
                          (msg->rsp[4] >> 2) & (~1),
                          (struct ipmi_addr *) &ipmb_addr,
                          &recv_msg)) {
                /*
                 * We were unable to find the sequence number,
                 * so just nuke the message.
                 */
                ipmi_inc_stat(intf, unhandled_ipmb_responses);
                return 0;
        }

        memcpy(recv_msg->msg_data, &msg->rsp[9], msg->rsp_size - 9);
        /*
         * The other fields matched, so no need to set them, except
         * for netfn, which needs to be the response that was
         * returned, not the request value.
         */
        recv_msg->msg.netfn = msg->rsp[4] >> 2;
        recv_msg->msg.data = recv_msg->msg_data;
        recv_msg->msg.data_len = msg->rsp_size - 10;
        recv_msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
        if (deliver_response(intf, recv_msg))
                ipmi_inc_stat(intf, unhandled_ipmb_responses);
        else
                ipmi_inc_stat(intf, handled_ipmb_responses);

        return 0;
}

static int handle_ipmb_get_msg_cmd(struct ipmi_smi *intf,
                                   struct ipmi_smi_msg *msg)
{
        struct cmd_rcvr          *rcvr;
        int                      rv = 0;
        unsigned char            netfn;
        unsigned char            cmd;
        unsigned char            chan;
        struct ipmi_user         *user = NULL;
        struct ipmi_ipmb_addr    *ipmb_addr;
        struct ipmi_recv_msg     *recv_msg;

        if (msg->rsp_size < 10) {
                /* Message not big enough, just ignore it. */
                ipmi_inc_stat(intf, invalid_commands);
                return 0;
        }

        if (msg->rsp[2] != 0) {
                /* An error getting the response, just ignore it. */
                return 0;
        }

        netfn = msg->rsp[4] >> 2;
        cmd = msg->rsp[8];
        chan = msg->rsp[3] & 0xf;

        rcu_read_lock();
        rcvr = find_cmd_rcvr(intf, netfn, cmd, chan);
        if (rcvr) {
                user = rcvr->user;
                kref_get(&user->refcount);
        } else
                user = NULL;
        rcu_read_unlock();

        if (user == NULL) {
                /* We didn't find a user, deliver an error response. */
                ipmi_inc_stat(intf, unhandled_commands);

                msg->data[0] = (IPMI_NETFN_APP_REQUEST << 2);
                msg->data[1] = IPMI_SEND_MSG_CMD;
                msg->data[2] = msg->rsp[3];
                msg->data[3] = msg->rsp[6];
                msg->data[4] = ((netfn + 1) << 2) | (msg->rsp[7] & 0x3);
                msg->data[5] = ipmb_checksum(&msg->data[3], 2);
                msg->data[6] = intf->addrinfo[msg->rsp[3] & 0xf].address;
                /* rqseq/lun */
                msg->data[7] = (msg->rsp[7] & 0xfc) | (msg->rsp[4] & 0x3);
                msg->data[8] = msg->rsp[8]; /* cmd */
                msg->data[9] = IPMI_INVALID_CMD_COMPLETION_CODE;
                msg->data[10] = ipmb_checksum(&msg->data[6], 4);
                msg->data_size = 11;

                ipmi_debug_msg("Invalid command:", msg->data, msg->data_size);

                rcu_read_lock();
                if (!intf->in_shutdown) {
                        smi_send(intf, intf->handlers, msg, 0);
                        /*
                         * We used the message, so return the value
                         * that causes it to not be freed or
                         * queued.
                         */
                        rv = -1;
                }
                rcu_read_unlock();
        } else {
                recv_msg = ipmi_alloc_recv_msg();
                if (!recv_msg) {
                        /*
                         * We couldn't allocate memory for the
                         * message, so requeue it for handling
                         * later.
                         */
                        rv = 1;
                        kref_put(&user->refcount, free_user);
                } else {
                        /* Extract the source address from the data. */
                        ipmb_addr = (struct ipmi_ipmb_addr *) &recv_msg->addr;
                        ipmb_addr->addr_type = IPMI_IPMB_ADDR_TYPE;
                        ipmb_addr->slave_addr = msg->rsp[6];
                        ipmb_addr->lun = msg->rsp[7] & 3;
                        ipmb_addr->channel = msg->rsp[3] & 0xf;

                        /*
                         * Extract the rest of the message information
                         * from the IPMB header.
                         */
                        recv_msg->user = user;
                        recv_msg->recv_type = IPMI_CMD_RECV_TYPE;
                        recv_msg->msgid = msg->rsp[7] >> 2;
                        recv_msg->msg.netfn = msg->rsp[4] >> 2;
                        recv_msg->msg.cmd = msg->rsp[8];
                        recv_msg->msg.data = recv_msg->msg_data;

                        /*
                         * We chop off 10, not 9 bytes because the checksum
                         * at the end also needs to be removed.
                         */
                        recv_msg->msg.data_len = msg->rsp_size - 10;
                        memcpy(recv_msg->msg_data, &msg->rsp[9],
                               msg->rsp_size - 10);
                        if (deliver_response(intf, recv_msg))
                                ipmi_inc_stat(intf, unhandled_commands);
                        else
                                ipmi_inc_stat(intf, handled_commands);
                }
        }

        return rv;
}

static int handle_lan_get_msg_rsp(struct ipmi_smi *intf,
                                  struct ipmi_smi_msg *msg)
{
        struct ipmi_lan_addr  lan_addr;
        struct ipmi_recv_msg  *recv_msg;


        /*
         * This is 13, not 12, because the response must contain a
         * completion code.
         */
        if (msg->rsp_size < 13) {
                /* Message not big enough, just ignore it. */
                ipmi_inc_stat(intf, invalid_lan_responses);
                return 0;
        }

        if (msg->rsp[2] != 0) {
                /* An error getting the response, just ignore it. */
                return 0;
        }

        lan_addr.addr_type = IPMI_LAN_ADDR_TYPE;
        lan_addr.session_handle = msg->rsp[4];
        lan_addr.remote_SWID = msg->rsp[8];
        lan_addr.local_SWID = msg->rsp[5];
        lan_addr.channel = msg->rsp[3] & 0x0f;
        lan_addr.privilege = msg->rsp[3] >> 4;
        lan_addr.lun = msg->rsp[9] & 3;

        /*
         * It's a response from a remote entity.  Look up the sequence
         * number and handle the response.
         */
        if (intf_find_seq(intf,
                          msg->rsp[9] >> 2,
                          msg->rsp[3] & 0x0f,
                          msg->rsp[10],
                          (msg->rsp[6] >> 2) & (~1),
                          (struct ipmi_addr *) &lan_addr,
                          &recv_msg)) {
                /*
                 * We were unable to find the sequence number,
                 * so just nuke the message.
                 */
                ipmi_inc_stat(intf, unhandled_lan_responses);
                return 0;
        }

        memcpy(recv_msg->msg_data, &msg->rsp[11], msg->rsp_size - 11);
        /*
         * The other fields matched, so no need to set them, except
         * for netfn, which needs to be the response that was
         * returned, not the request value.
         */
        recv_msg->msg.netfn = msg->rsp[6] >> 2;
        recv_msg->msg.data = recv_msg->msg_data;
        recv_msg->msg.data_len = msg->rsp_size - 12;
        recv_msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
        if (deliver_response(intf, recv_msg))
                ipmi_inc_stat(intf, unhandled_lan_responses);
        else
                ipmi_inc_stat(intf, handled_lan_responses);

        return 0;
}

static int handle_lan_get_msg_cmd(struct ipmi_smi *intf,
                                  struct ipmi_smi_msg *msg)
{
        struct cmd_rcvr          *rcvr;
        int                      rv = 0;
        unsigned char            netfn;
        unsigned char            cmd;
        unsigned char            chan;
        struct ipmi_user         *user = NULL;
        struct ipmi_lan_addr     *lan_addr;
        struct ipmi_recv_msg     *recv_msg;

        if (msg->rsp_size < 12) {
                /* Message not big enough, just ignore it. */
                ipmi_inc_stat(intf, invalid_commands);
                return 0;
        }

        if (msg->rsp[2] != 0) {
                /* An error getting the response, just ignore it. */
                return 0;
        }

        netfn = msg->rsp[6] >> 2;
        cmd = msg->rsp[10];
        chan = msg->rsp[3] & 0xf;

        rcu_read_lock();
        rcvr = find_cmd_rcvr(intf, netfn, cmd, chan);
        if (rcvr) {
                user = rcvr->user;
                kref_get(&user->refcount);
        } else
                user = NULL;
        rcu_read_unlock();

        if (user == NULL) {
                /* We didn't find a user, just give up. */
                ipmi_inc_stat(intf, unhandled_commands);

                /*
                 * Don't do anything with these messages, just allow
                 * them to be freed.
                 */
                rv = 0;
        } else {
                recv_msg = ipmi_alloc_recv_msg();
                if (!recv_msg) {
                        /*
                         * We couldn't allocate memory for the
                         * message, so requeue it for handling later.
                         */
                        rv = 1;
                        kref_put(&user->refcount, free_user);
                } else {
                        /* Extract the source address from the data. */
                        lan_addr = (struct ipmi_lan_addr *) &recv_msg->addr;
                        lan_addr->addr_type = IPMI_LAN_ADDR_TYPE;
                        lan_addr->session_handle = msg->rsp[4];
                        lan_addr->remote_SWID = msg->rsp[8];
                        lan_addr->local_SWID = msg->rsp[5];
                        lan_addr->lun = msg->rsp[9] & 3;
                        lan_addr->channel = msg->rsp[3] & 0xf;
                        lan_addr->privilege = msg->rsp[3] >> 4;

                        /*
                         * Extract the rest of the message information
                         * from the IPMB header.
                         */
                        recv_msg->user = user;
                        recv_msg->recv_type = IPMI_CMD_RECV_TYPE;
                        recv_msg->msgid = msg->rsp[9] >> 2;
                        recv_msg->msg.netfn = msg->rsp[6] >> 2;
                        recv_msg->msg.cmd = msg->rsp[10];
                        recv_msg->msg.data = recv_msg->msg_data;

                        /*
                         * We chop off 12, not 11 bytes because the checksum
                         * at the end also needs to be removed.
                         */
                        recv_msg->msg.data_len = msg->rsp_size - 12;
                        memcpy(recv_msg->msg_data, &msg->rsp[11],
                               msg->rsp_size - 12);
                        if (deliver_response(intf, recv_msg))
                                ipmi_inc_stat(intf, unhandled_commands);
                        else
                                ipmi_inc_stat(intf, handled_commands);
                }
        }

        return rv;
}

/*
 * This routine will handle "Get Message" command responses with
 * channels that use an OEM Medium. The message format belongs to
 * the OEM.  See IPMI 2.0 specification, Chapter 6 and
 * Chapter 22, sections 22.6 and 22.24 for more details.
 */
static int handle_oem_get_msg_cmd(struct ipmi_smi *intf,
                                  struct ipmi_smi_msg *msg)
{
        struct cmd_rcvr       *rcvr;
        int                   rv = 0;
        unsigned char         netfn;
        unsigned char         cmd;
        unsigned char         chan;
        struct ipmi_user *user = NULL;
        struct ipmi_system_interface_addr *smi_addr;
        struct ipmi_recv_msg  *recv_msg;

        /*
         * We expect the OEM SW to perform error checking
         * so we just do some basic sanity checks
         */
        if (msg->rsp_size < 4) {
                /* Message not big enough, just ignore it. */
                ipmi_inc_stat(intf, invalid_commands);
                return 0;
        }

        if (msg->rsp[2] != 0) {
                /* An error getting the response, just ignore it. */
                return 0;
        }

        /*
         * This is an OEM Message so the OEM needs to know how
         * handle the message. We do no interpretation.
         */
        netfn = msg->rsp[0] >> 2;
        cmd = msg->rsp[1];
        chan = msg->rsp[3] & 0xf;

        rcu_read_lock();
        rcvr = find_cmd_rcvr(intf, netfn, cmd, chan);
        if (rcvr) {
                user = rcvr->user;
                kref_get(&user->refcount);
        } else
                user = NULL;
        rcu_read_unlock();

        if (user == NULL) {
                /* We didn't find a user, just give up. */
                ipmi_inc_stat(intf, unhandled_commands);

                /*
                 * Don't do anything with these messages, just allow
                 * them to be freed.
                 */

                rv = 0;
        } else {
                recv_msg = ipmi_alloc_recv_msg();
                if (!recv_msg) {
                        /*
                         * We couldn't allocate memory for the
                         * message, so requeue it for handling
                         * later.
                         */
                        rv = 1;
                        kref_put(&user->refcount, free_user);
                } else {
                        /*
                         * OEM Messages are expected to be delivered via
                         * the system interface to SMS software.  We might
                         * need to visit this again depending on OEM
                         * requirements
                         */
                        smi_addr = ((struct ipmi_system_interface_addr *)
                                    &recv_msg->addr);
                        smi_addr->addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
                        smi_addr->channel = IPMI_BMC_CHANNEL;
                        smi_addr->lun = msg->rsp[0] & 3;

                        recv_msg->user = user;
                        recv_msg->user_msg_data = NULL;
                        recv_msg->recv_type = IPMI_OEM_RECV_TYPE;
                        recv_msg->msg.netfn = msg->rsp[0] >> 2;
                        recv_msg->msg.cmd = msg->rsp[1];
                        recv_msg->msg.data = recv_msg->msg_data;

                        /*
                         * The message starts at byte 4 which follows the
                         * the Channel Byte in the "GET MESSAGE" command
                         */
                        recv_msg->msg.data_len = msg->rsp_size - 4;
                        memcpy(recv_msg->msg_data, &msg->rsp[4],
                               msg->rsp_size - 4);
                        if (deliver_response(intf, recv_msg))
                                ipmi_inc_stat(intf, unhandled_commands);
                        else
                                ipmi_inc_stat(intf, handled_commands);
                }
        }

        return rv;
}

static void copy_event_into_recv_msg(struct ipmi_recv_msg *recv_msg,
                                     struct ipmi_smi_msg  *msg)
{
        struct ipmi_system_interface_addr *smi_addr;

        recv_msg->msgid = 0;
        smi_addr = (struct ipmi_system_interface_addr *) &recv_msg->addr;
        smi_addr->addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
        smi_addr->channel = IPMI_BMC_CHANNEL;
        smi_addr->lun = msg->rsp[0] & 3;
        recv_msg->recv_type = IPMI_ASYNC_EVENT_RECV_TYPE;
        recv_msg->msg.netfn = msg->rsp[0] >> 2;
        recv_msg->msg.cmd = msg->rsp[1];
        memcpy(recv_msg->msg_data, &msg->rsp[3], msg->rsp_size - 3);
        recv_msg->msg.data = recv_msg->msg_data;
        recv_msg->msg.data_len = msg->rsp_size - 3;
}

static int handle_read_event_rsp(struct ipmi_smi *intf,
                                 struct ipmi_smi_msg *msg)
{
        struct ipmi_recv_msg *recv_msg, *recv_msg2;
        struct list_head     msgs;
        struct ipmi_user     *user;
        int rv = 0, deliver_count = 0, index;
        unsigned long        flags;

        if (msg->rsp_size < 19) {
                /* Message is too small to be an IPMB event. */
                ipmi_inc_stat(intf, invalid_events);
                return 0;
        }

        if (msg->rsp[2] != 0) {
                /* An error getting the event, just ignore it. */
                return 0;
        }

        INIT_LIST_HEAD(&msgs);

        spin_lock_irqsave(&intf->events_lock, flags);

        ipmi_inc_stat(intf, events);

        /*
         * Allocate and fill in one message for every user that is
         * getting events.
         */
        index = srcu_read_lock(&intf->users_srcu);
        list_for_each_entry_rcu(user, &intf->users, link) {
                if (!user->gets_events)
                        continue;

                recv_msg = ipmi_alloc_recv_msg();
                if (!recv_msg) {
                        rcu_read_unlock();
                        list_for_each_entry_safe(recv_msg, recv_msg2, &msgs,
                                                 link) {
                                list_del(&recv_msg->link);
                                ipmi_free_recv_msg(recv_msg);
                        }
                        /*
                         * We couldn't allocate memory for the
                         * message, so requeue it for handling
                         * later.
                         */
                        rv = 1;
                        goto out;
                }

                deliver_count++;

                copy_event_into_recv_msg(recv_msg, msg);
                recv_msg->user = user;
                kref_get(&user->refcount);
                list_add_tail(&recv_msg->link, &msgs);
        }
        srcu_read_unlock(&intf->users_srcu, index);

        if (deliver_count) {
                /* Now deliver all the messages. */
                list_for_each_entry_safe(recv_msg, recv_msg2, &msgs, link) {
                        list_del(&recv_msg->link);
                        deliver_local_response(intf, recv_msg);
                }
        } else if (intf->waiting_events_count < MAX_EVENTS_IN_QUEUE) {
                /*
                 * No one to receive the message, put it in queue if there's
                 * not already too many things in the queue.
                 */
                recv_msg = ipmi_alloc_recv_msg();
                if (!recv_msg) {
                        /*
                         * We couldn't allocate memory for the
                         * message, so requeue it for handling
                         * later.
                         */
                        rv = 1;
                        goto out;
                }

                copy_event_into_recv_msg(recv_msg, msg);
                list_add_tail(&recv_msg->link, &intf->waiting_events);
                intf->waiting_events_count++;
        } else if (!intf->event_msg_printed) {
                /*
                 * There's too many things in the queue, discard this
                 * message.
                 */
                dev_warn(intf->si_dev,
                         PFX "Event queue full, discarding incoming events\n");
                intf->event_msg_printed = 1;
        }

 out:
        spin_unlock_irqrestore(&intf->events_lock, flags);

        return rv;
}

static int handle_bmc_rsp(struct ipmi_smi *intf,
                          struct ipmi_smi_msg *msg)
{
        struct ipmi_recv_msg *recv_msg;
        struct ipmi_system_interface_addr *smi_addr;

        recv_msg = (struct ipmi_recv_msg *) msg->user_data;
        if (recv_msg == NULL) {
                dev_warn(intf->si_dev,
                         "IPMI message received with no owner. This could be because of a malformed message, or because of a hardware error.  Contact your hardware vender for assistance\n");
                return 0;
        }

        recv_msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
        recv_msg->msgid = msg->msgid;
        smi_addr = ((struct ipmi_system_interface_addr *)
                    &recv_msg->addr);
        smi_addr->addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
        smi_addr->channel = IPMI_BMC_CHANNEL;
        smi_addr->lun = msg->rsp[0] & 3;
        recv_msg->msg.netfn = msg->rsp[0] >> 2;
        recv_msg->msg.cmd = msg->rsp[1];
        memcpy(recv_msg->msg_data, &msg->rsp[2], msg->rsp_size - 2);
        recv_msg->msg.data = recv_msg->msg_data;
        recv_msg->msg.data_len = msg->rsp_size - 2;
        deliver_local_response(intf, recv_msg);

        return 0;
}

/*
 * Handle a received message.  Return 1 if the message should be requeued,
 * 0 if the message should be freed, or -1 if the message should not
 * be freed or requeued.
 */
static int handle_one_recv_msg(struct ipmi_smi *intf,
                               struct ipmi_smi_msg *msg)
{
        int requeue;
        int chan;

        ipmi_debug_msg("Recv:", msg->rsp, msg->rsp_size);
        if (msg->rsp_size < 2) {
                /* Message is too small to be correct. */
                dev_warn(intf->si_dev,
                         PFX "BMC returned to small a message for netfn %x cmd %x, got %d bytes\n",
                         (msg->data[0] >> 2) | 1, msg->data[1], msg->rsp_size);

                /* Generate an error response for the message. */
                msg->rsp[0] = msg->data[0] | (1 << 2);
                msg->rsp[1] = msg->data[1];
                msg->rsp[2] = IPMI_ERR_UNSPECIFIED;
                msg->rsp_size = 3;
        } else if (((msg->rsp[0] >> 2) != ((msg->data[0] >> 2) | 1))
                   || (msg->rsp[1] != msg->data[1])) {
                /*
                 * The NetFN and Command in the response is not even
                 * marginally correct.
                 */
                dev_warn(intf->si_dev,
                         PFX "BMC returned incorrect response, expected netfn %x cmd %x, got netfn %x cmd %x\n",
                         (msg->data[0] >> 2) | 1, msg->data[1],
                         msg->rsp[0] >> 2, msg->rsp[1]);

                /* Generate an error response for the message. */
                msg->rsp[0] = msg->data[0] | (1 << 2);
                msg->rsp[1] = msg->data[1];
                msg->rsp[2] = IPMI_ERR_UNSPECIFIED;
                msg->rsp_size = 3;
        }

        if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
            && (msg->rsp[1] == IPMI_SEND_MSG_CMD)
            && (msg->user_data != NULL)) {
                /*
                 * It's a response to a response we sent.  For this we
                 * deliver a send message response to the user.
                 */
                struct ipmi_recv_msg *recv_msg = msg->user_data;

                requeue = 0;
                if (msg->rsp_size < 2)
                        /* Message is too small to be correct. */
                        goto out;

                chan = msg->data[2] & 0x0f;
                if (chan >= IPMI_MAX_CHANNELS)
                        /* Invalid channel number */
                        goto out;

                if (!recv_msg)
                        goto out;

                recv_msg->recv_type = IPMI_RESPONSE_RESPONSE_TYPE;
                recv_msg->msg.data = recv_msg->msg_data;
                recv_msg->msg.data_len = 1;
                recv_msg->msg_data[0] = msg->rsp[2];
                deliver_local_response(intf, recv_msg);
        } else if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
                   && (msg->rsp[1] == IPMI_GET_MSG_CMD)) {
                struct ipmi_channel   *chans;

                /* It's from the receive queue. */
                chan = msg->rsp[3] & 0xf;
                if (chan >= IPMI_MAX_CHANNELS) {
                        /* Invalid channel number */
                        requeue = 0;
                        goto out;
                }

                /*
                 * We need to make sure the channels have been initialized.
                 * The channel_handler routine will set the "curr_channel"
                 * equal to or greater than IPMI_MAX_CHANNELS when all the
                 * channels for this interface have been initialized.
                 */
                if (!intf->channels_ready) {
                        requeue = 0; /* Throw the message away */
                        goto out;
                }

                chans = READ_ONCE(intf->channel_list)->c;

                switch (chans[chan].medium) {
                case IPMI_CHANNEL_MEDIUM_IPMB:
                        if (msg->rsp[4] & 0x04) {
                                /*
                                 * It's a response, so find the
                                 * requesting message and send it up.
                                 */
                                requeue = handle_ipmb_get_msg_rsp(intf, msg);
                        } else {
                                /*
                                 * It's a command to the SMS from some other
                                 * entity.  Handle that.
                                 */
                                requeue = handle_ipmb_get_msg_cmd(intf, msg);
                        }
                        break;

                case IPMI_CHANNEL_MEDIUM_8023LAN:
                case IPMI_CHANNEL_MEDIUM_ASYNC:
                        if (msg->rsp[6] & 0x04) {
                                /*
                                 * It's a response, so find the
                                 * requesting message and send it up.
                                 */
                                requeue = handle_lan_get_msg_rsp(intf, msg);
                        } else {
                                /*
                                 * It's a command to the SMS from some other
                                 * entity.  Handle that.
                                 */
                                requeue = handle_lan_get_msg_cmd(intf, msg);
                        }
                        break;

                default:
                        /* Check for OEM Channels.  Clients had better
                           register for these commands. */
                        if ((chans[chan].medium >= IPMI_CHANNEL_MEDIUM_OEM_MIN)
                            && (chans[chan].medium
                                <= IPMI_CHANNEL_MEDIUM_OEM_MAX)) {
                                requeue = handle_oem_get_msg_cmd(intf, msg);
                        } else {
                                /*
                                 * We don't handle the channel type, so just
                                 * free the message.
                                 */
                                requeue = 0;
                        }
                }

        } else if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
                   && (msg->rsp[1] == IPMI_READ_EVENT_MSG_BUFFER_CMD)) {
                /* It's an asynchronous event. */
                requeue = handle_read_event_rsp(intf, msg);
        } else {
                /* It's a response from the local BMC. */
                requeue = handle_bmc_rsp(intf, msg);
        }

 out:
        return requeue;
}

/*
 * If there are messages in the queue or pretimeouts, handle them.
 */
static void handle_new_recv_msgs(struct ipmi_smi *intf)
{
        struct ipmi_smi_msg  *smi_msg;
        unsigned long        flags = 0;
        int                  rv;
        int                  run_to_completion = intf->run_to_completion;

        /* See if any waiting messages need to be processed. */
        if (!run_to_completion)
                spin_lock_irqsave(&intf->waiting_rcv_msgs_lock, flags);
        while (!list_empty(&intf->waiting_rcv_msgs)) {
                smi_msg = list_entry(intf->waiting_rcv_msgs.next,
                                     struct ipmi_smi_msg, link);
                list_del(&smi_msg->link);
                if (!run_to_completion)
                        spin_unlock_irqrestore(&intf->waiting_rcv_msgs_lock,
                                               flags);
                rv = handle_one_recv_msg(intf, smi_msg);
                if (!run_to_completion)
                        spin_lock_irqsave(&intf->waiting_rcv_msgs_lock, flags);
                if (rv > 0) {
                        /*
                         * To preserve message order, quit if we
                         * can't handle a message.  Add the message
                         * back at the head, this is safe because this
                         * tasklet is the only thing that pulls the
                         * messages.
                         */
                        list_add(&smi_msg->link, &intf->waiting_rcv_msgs);
                        break;
                } else {
                        if (rv == 0)
                                /* Message handled */
                                ipmi_free_smi_msg(smi_msg);
                        /* If rv < 0, fatal error, del but don't free. */
                }
        }
        if (!run_to_completion)
                spin_unlock_irqrestore(&intf->waiting_rcv_msgs_lock, flags);

        /*
         * If the pretimout count is non-zero, decrement one from it and
         * deliver pretimeouts to all the users.
         */
        if (atomic_add_unless(&intf->watchdog_pretimeouts_to_deliver, -1, 0)) {
                struct ipmi_user *user;
                int index;

                index = srcu_read_lock(&intf->users_srcu);
                list_for_each_entry_rcu(user, &intf->users, link) {
                        if (user->handler->ipmi_watchdog_pretimeout)
                                user->handler->ipmi_watchdog_pretimeout(
                                        user->handler_data);
                }
                srcu_read_unlock(&intf->users_srcu, index);
        }
}

static void smi_recv_tasklet(unsigned long val)
{
        unsigned long flags = 0; /* keep us warning-free. */
        struct ipmi_smi *intf = (struct ipmi_smi *) val;
        int run_to_completion = intf->run_to_completion;
        struct ipmi_smi_msg *newmsg = NULL;

        /*
         * Start the next message if available.
         *
         * Do this here, not in the actual receiver, because we may deadlock
         * because the lower layer is allowed to hold locks while calling
         * message delivery.
         */

        rcu_read_lock();

        if (!run_to_completion)
                spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
        if (intf->curr_msg == NULL && !intf->in_shutdown) {
                struct list_head *entry = NULL;

                /* Pick the high priority queue first. */
                if (!list_empty(&intf->hp_xmit_msgs))
                        entry = intf->hp_xmit_msgs.next;
                else if (!list_empty(&intf->xmit_msgs))
                        entry = intf->xmit_msgs.next;

                if (entry) {
                        list_del(entry);
                        newmsg = list_entry(entry, struct ipmi_smi_msg, link);
                        intf->curr_msg = newmsg;
                }
        }
        if (!run_to_completion)
                spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
        if (newmsg)
                intf->handlers->sender(intf->send_info, newmsg);

        rcu_read_unlock();

        handle_new_recv_msgs(intf);
}

/* Handle a new message from the lower layer. */
void ipmi_smi_msg_received(struct ipmi_smi *intf,
                           struct ipmi_smi_msg *msg)
{
        unsigned long flags = 0; /* keep us warning-free. */
        int run_to_completion = intf->run_to_completion;

        if ((msg->data_size >= 2)
            && (msg->data[0] == (IPMI_NETFN_APP_REQUEST << 2))
            && (msg->data[1] == IPMI_SEND_MSG_CMD)
            && (msg->user_data == NULL)) {

                if (intf->in_shutdown)
                        goto free_msg;

                /*
                 * This is the local response to a command send, start
                 * the timer for these.  The user_data will not be
                 * NULL if this is a response send, and we will let
                 * response sends just go through.
                 */

                /*
                 * Check for errors, if we get certain errors (ones
                 * that mean basically we can try again later), we
                 * ignore them and start the timer.  Otherwise we
                 * report the error immediately.
                 */
                if ((msg->rsp_size >= 3) && (msg->rsp[2] != 0)
                    && (msg->rsp[2] != IPMI_NODE_BUSY_ERR)
                    && (msg->rsp[2] != IPMI_LOST_ARBITRATION_ERR)
                    && (msg->rsp[2] != IPMI_BUS_ERR)
                    && (msg->rsp[2] != IPMI_NAK_ON_WRITE_ERR)) {
                        int ch = msg->rsp[3] & 0xf;
                        struct ipmi_channel *chans;

                        /* Got an error sending the message, handle it. */

                        chans = READ_ONCE(intf->channel_list)->c;
                        if ((chans[ch].medium == IPMI_CHANNEL_MEDIUM_8023LAN)
                            || (chans[ch].medium == IPMI_CHANNEL_MEDIUM_ASYNC))
                                ipmi_inc_stat(intf, sent_lan_command_errs);
                        else
                                ipmi_inc_stat(intf, sent_ipmb_command_errs);
                        intf_err_seq(intf, msg->msgid, msg->rsp[2]);
                } else
                        /* The message was sent, start the timer. */
                        intf_start_seq_timer(intf, msg->msgid);

free_msg:
                ipmi_free_smi_msg(msg);
        } else {
                /*
                 * To preserve message order, we keep a queue and deliver from
                 * a tasklet.
                 */
                if (!run_to_completion)
                        spin_lock_irqsave(&intf->waiting_rcv_msgs_lock, flags);
                list_add_tail(&msg->link, &intf->waiting_rcv_msgs);
                if (!run_to_completion)
                        spin_unlock_irqrestore(&intf->waiting_rcv_msgs_lock,
                                               flags);
        }

        if (!run_to_completion)
                spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
        /*
         * We can get an asynchronous event or receive message in addition
         * to commands we send.
         */
        if (msg == intf->curr_msg)
                intf->curr_msg = NULL;
        if (!run_to_completion)
                spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);

        if (run_to_completion)
                smi_recv_tasklet((unsigned long) intf);
        else
                tasklet_schedule(&intf->recv_tasklet);
}
EXPORT_SYMBOL(ipmi_smi_msg_received);

void ipmi_smi_watchdog_pretimeout(struct ipmi_smi *intf)
{
        if (intf->in_shutdown)
                return;

        atomic_set(&intf->watchdog_pretimeouts_to_deliver, 1);
        tasklet_schedule(&intf->recv_tasklet);
}
EXPORT_SYMBOL(ipmi_smi_watchdog_pretimeout);

static struct ipmi_smi_msg *
smi_from_recv_msg(struct ipmi_smi *intf, struct ipmi_recv_msg *recv_msg,
                  unsigned char seq, long seqid)
{
        struct ipmi_smi_msg *smi_msg = ipmi_alloc_smi_msg();
        if (!smi_msg)
                /*
                 * If we can't allocate the message, then just return, we
                 * get 4 retries, so this should be ok.
                 */
                return NULL;

        memcpy(smi_msg->data, recv_msg->msg.data, recv_msg->msg.data_len);
        smi_msg->data_size = recv_msg->msg.data_len;
        smi_msg->msgid = STORE_SEQ_IN_MSGID(seq, seqid);

        ipmi_debug_msg("Resend: ", smi_msg->data, smi_msg->data_size);

        return smi_msg;
}

static void check_msg_timeout(struct ipmi_smi *intf, struct seq_table *ent,
                              struct list_head *timeouts,
                              unsigned long timeout_period,
                              int slot, unsigned long *flags,
                              unsigned int *waiting_msgs)
{
        struct ipmi_recv_msg *msg;

        if (intf->in_shutdown)
                return;

        if (!ent->inuse)
                return;

        if (timeout_period < ent->timeout) {
                ent->timeout -= timeout_period;
                (*waiting_msgs)++;
                return;
        }

        if (ent->retries_left == 0) {
                /* The message has used all its retries. */
                ent->inuse = 0;
                msg = ent->recv_msg;
                list_add_tail(&msg->link, timeouts);
                if (ent->broadcast)
                        ipmi_inc_stat(intf, timed_out_ipmb_broadcasts);
                else if (is_lan_addr(&ent->recv_msg->addr))
                        ipmi_inc_stat(intf, timed_out_lan_commands);
                else
                        ipmi_inc_stat(intf, timed_out_ipmb_commands);
        } else {
                struct ipmi_smi_msg *smi_msg;
                /* More retries, send again. */

                (*waiting_msgs)++;

                /*
                 * Start with the max timer, set to normal timer after
                 * the message is sent.
                 */
                ent->timeout = MAX_MSG_TIMEOUT;
                ent->retries_left--;
                smi_msg = smi_from_recv_msg(intf, ent->recv_msg, slot,
                                            ent->seqid);
                if (!smi_msg) {
                        if (is_lan_addr(&ent->recv_msg->addr))
                                ipmi_inc_stat(intf,
                                              dropped_rexmit_lan_commands);
                        else
                                ipmi_inc_stat(intf,
                                              dropped_rexmit_ipmb_commands);
                        return;
                }

                spin_unlock_irqrestore(&intf->seq_lock, *flags);

                /*
                 * Send the new message.  We send with a zero
                 * priority.  It timed out, I doubt time is that
                 * critical now, and high priority messages are really
                 * only for messages to the local MC, which don't get
                 * resent.
                 */
                if (intf->handlers) {
                        if (is_lan_addr(&ent->recv_msg->addr))
                                ipmi_inc_stat(intf,
                                              retransmitted_lan_commands);
                        else
                                ipmi_inc_stat(intf,
                                              retransmitted_ipmb_commands);

                        smi_send(intf, intf->handlers, smi_msg, 0);
                } else
                        ipmi_free_smi_msg(smi_msg);

                spin_lock_irqsave(&intf->seq_lock, *flags);
        }
}

static unsigned int ipmi_timeout_handler(struct ipmi_smi *intf,
                                         unsigned long timeout_period)
{
        struct list_head     timeouts;
        struct ipmi_recv_msg *msg, *msg2;
        unsigned long        flags;
        int                  i;
        unsigned int         waiting_msgs = 0;

        if (!intf->bmc_registered) {
                kref_get(&intf->refcount);
                if (!schedule_work(&intf->bmc_reg_work)) {
                        kref_put(&intf->refcount, intf_free);
                        waiting_msgs++;
                }
        }

        /*
         * Go through the seq table and find any messages that
         * have timed out, putting them in the timeouts
         * list.
         */
        INIT_LIST_HEAD(&timeouts);
        spin_lock_irqsave(&intf->seq_lock, flags);
        if (intf->ipmb_maintenance_mode_timeout) {
                if (intf->ipmb_maintenance_mode_timeout <= timeout_period)
                        intf->ipmb_maintenance_mode_timeout = 0;
                else
                        intf->ipmb_maintenance_mode_timeout -= timeout_period;
        }
        for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++)
                check_msg_timeout(intf, &intf->seq_table[i],
                                  &timeouts, timeout_period, i,
                                  &flags, &waiting_msgs);
        spin_unlock_irqrestore(&intf->seq_lock, flags);

        list_for_each_entry_safe(msg, msg2, &timeouts, link)
                deliver_err_response(intf, msg, IPMI_TIMEOUT_COMPLETION_CODE);

        /*
         * Maintenance mode handling.  Check the timeout
         * optimistically before we claim the lock.  It may
         * mean a timeout gets missed occasionally, but that
         * only means the timeout gets extended by one period
         * in that case.  No big deal, and it avoids the lock
         * most of the time.
         */
        if (intf->auto_maintenance_timeout > 0) {
                spin_lock_irqsave(&intf->maintenance_mode_lock, flags);
                if (intf->auto_maintenance_timeout > 0) {
                        intf->auto_maintenance_timeout
                                -= timeout_period;
                        if (!intf->maintenance_mode
                            && (intf->auto_maintenance_timeout <= 0)) {
                                intf->maintenance_mode_enable = false;
                                maintenance_mode_update(intf);
                        }
                }
                spin_unlock_irqrestore(&intf->maintenance_mode_lock,
                                       flags);
        }

        tasklet_schedule(&intf->recv_tasklet);

        return waiting_msgs;
}

static void ipmi_request_event(struct ipmi_smi *intf)
{
        /* No event requests when in maintenance mode. */
        if (intf->maintenance_mode_enable)
                return;

        if (!intf->in_shutdown)
                intf->handlers->request_events(intf->send_info);
}

static struct timer_list ipmi_timer;

static atomic_t stop_operation;

static void ipmi_timeout(struct timer_list *unused)
{
        struct ipmi_smi *intf;
        int nt = 0, index;

        if (atomic_read(&stop_operation))
                return;

        index = srcu_read_lock(&ipmi_interfaces_srcu);
        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
                int lnt = 0;

                if (atomic_read(&intf->event_waiters)) {
                        intf->ticks_to_req_ev--;
                        if (intf->ticks_to_req_ev == 0) {
                                ipmi_request_event(intf);
                                intf->ticks_to_req_ev = IPMI_REQUEST_EV_TIME;
                        }
                        lnt++;
                }

                lnt += ipmi_timeout_handler(intf, IPMI_TIMEOUT_TIME);

                lnt = !!lnt;
                if (lnt != intf->last_needs_timer &&
                                        intf->handlers->set_need_watch)
                        intf->handlers->set_need_watch(intf->send_info, lnt);
                intf->last_needs_timer = lnt;

                nt += lnt;
        }
        srcu_read_unlock(&ipmi_interfaces_srcu, index);

        if (nt)
                mod_timer(&ipmi_timer, jiffies + IPMI_TIMEOUT_JIFFIES);
}

static void need_waiter(struct ipmi_smi *intf)
{
        /* Racy, but worst case we start the timer twice. */
        if (!timer_pending(&ipmi_timer))
                mod_timer(&ipmi_timer, jiffies + IPMI_TIMEOUT_JIFFIES);
}

static atomic_t smi_msg_inuse_count = ATOMIC_INIT(0);
static atomic_t recv_msg_inuse_count = ATOMIC_INIT(0);

static void free_smi_msg(struct ipmi_smi_msg *msg)
{
        atomic_dec(&smi_msg_inuse_count);
        kfree(msg);
}

struct ipmi_smi_msg *ipmi_alloc_smi_msg(void)
{
        struct ipmi_smi_msg *rv;
        rv = kmalloc(sizeof(struct ipmi_smi_msg), GFP_ATOMIC);
        if (rv) {
                rv->done = free_smi_msg;
                rv->user_data = NULL;
                atomic_inc(&smi_msg_inuse_count);
        }
        return rv;
}
EXPORT_SYMBOL(ipmi_alloc_smi_msg);

static void free_recv_msg(struct ipmi_recv_msg *msg)
{
        atomic_dec(&recv_msg_inuse_count);
        kfree(msg);
}

static struct ipmi_recv_msg *ipmi_alloc_recv_msg(void)
{
        struct ipmi_recv_msg *rv;

        rv = kmalloc(sizeof(struct ipmi_recv_msg), GFP_ATOMIC);
        if (rv) {
                rv->user = NULL;
                rv->done = free_recv_msg;
                atomic_inc(&recv_msg_inuse_count);
        }
        return rv;
}

void ipmi_free_recv_msg(struct ipmi_recv_msg *msg)
{
        if (msg->user)
                kref_put(&msg->user->refcount, free_user);
        msg->done(msg);
}
EXPORT_SYMBOL(ipmi_free_recv_msg);

static atomic_t panic_done_count = ATOMIC_INIT(0);

static void dummy_smi_done_handler(struct ipmi_smi_msg *msg)
{
        atomic_dec(&panic_done_count);
}

static void dummy_recv_done_handler(struct ipmi_recv_msg *msg)
{
        atomic_dec(&panic_done_count);
}

/*
 * Inside a panic, send a message and wait for a response.
 */
static void ipmi_panic_request_and_wait(struct ipmi_smi *intf,
                                        struct ipmi_addr *addr,
                                        struct kernel_ipmi_msg *msg)
{
        struct ipmi_smi_msg  smi_msg;
        struct ipmi_recv_msg recv_msg;
        int rv;

        smi_msg.done = dummy_smi_done_handler;
        recv_msg.done = dummy_recv_done_handler;
        atomic_add(2, &panic_done_count);
        rv = i_ipmi_request(NULL,
                            intf,
                            addr,
                            0,
                            msg,
                            intf,
                            &smi_msg,
                            &recv_msg,
                            0,
                            intf->addrinfo[0].address,
                            intf->addrinfo[0].lun,
                            0, 1); /* Don't retry, and don't wait. */
        if (rv)
                atomic_sub(2, &panic_done_count);
        else if (intf->handlers->flush_messages)
                intf->handlers->flush_messages(intf->send_info);

        while (atomic_read(&panic_done_count) != 0)
                ipmi_poll(intf);
}

static void event_receiver_fetcher(struct ipmi_smi *intf,
                                   struct ipmi_recv_msg *msg)
{
        if ((msg->addr.addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE)
            && (msg->msg.netfn == IPMI_NETFN_SENSOR_EVENT_RESPONSE)
            && (msg->msg.cmd == IPMI_GET_EVENT_RECEIVER_CMD)
            && (msg->msg.data[0] == IPMI_CC_NO_ERROR)) {
                /* A get event receiver command, save it. */
                intf->event_receiver = msg->msg.data[1];
                intf->event_receiver_lun = msg->msg.data[2] & 0x3;
        }
}

static void device_id_fetcher(struct ipmi_smi *intf, struct ipmi_recv_msg *msg)
{
        if ((msg->addr.addr_type == IPMI_SYSTEM_INTERFACE_ADDR_TYPE)
            && (msg->msg.netfn == IPMI_NETFN_APP_RESPONSE)
            && (msg->msg.cmd == IPMI_GET_DEVICE_ID_CMD)
            && (msg->msg.data[0] == IPMI_CC_NO_ERROR)) {
                /*
                 * A get device id command, save if we are an event
                 * receiver or generator.
                 */
                intf->local_sel_device = (msg->msg.data[6] >> 2) & 1;
                intf->local_event_generator = (msg->msg.data[6] >> 5) & 1;
        }
}

static void send_panic_events(struct ipmi_smi *intf, char *str)
{
        struct kernel_ipmi_msg msg;
        unsigned char data[16];
        struct ipmi_system_interface_addr *si;
        struct ipmi_addr addr;
        char *p = str;
        struct ipmi_ipmb_addr *ipmb;
        int j;

        if (ipmi_send_panic_event == IPMI_SEND_PANIC_EVENT_NONE)
                return;

        si = (struct ipmi_system_interface_addr *) &addr;
        si->addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
        si->channel = IPMI_BMC_CHANNEL;
        si->lun = 0;

        /* Fill in an event telling that we have failed. */
        msg.netfn = 0x04; /* Sensor or Event. */
        msg.cmd = 2; /* Platform event command. */
        msg.data = data;
        msg.data_len = 8;
        data[0] = 0x41; /* Kernel generator ID, IPMI table 5-4 */
        data[1] = 0x03; /* This is for IPMI 1.0. */
        data[2] = 0x20; /* OS Critical Stop, IPMI table 36-3 */
        data[4] = 0x6f; /* Sensor specific, IPMI table 36-1 */
        data[5] = 0xa1; /* Runtime stop OEM bytes 2 & 3. */

        /*
         * Put a few breadcrumbs in.  Hopefully later we can add more things
         * to make the panic events more useful.
         */
        if (str) {
                data[3] = str[0];
                data[6] = str[1];
                data[7] = str[2];
        }

        /* Send the event announcing the panic. */
        ipmi_panic_request_and_wait(intf, &addr, &msg);

        /*
         * On every interface, dump a bunch of OEM event holding the
         * string.
         */
        if (ipmi_send_panic_event != IPMI_SEND_PANIC_EVENT_STRING || !str)
                return;

        /*
         * intf_num is used as an marker to tell if the
         * interface is valid.  Thus we need a read barrier to
         * make sure data fetched before checking intf_num
         * won't be used.
         */
        smp_rmb();

        /*
         * First job here is to figure out where to send the
         * OEM events.  There's no way in IPMI to send OEM
         * events using an event send command, so we have to
         * find the SEL to put them in and stick them in
         * there.
         */

        /* Get capabilities from the get device id. */
        intf->local_sel_device = 0;
        intf->local_event_generator = 0;
        intf->event_receiver = 0;

        /* Request the device info from the local MC. */
        msg.netfn = IPMI_NETFN_APP_REQUEST;
        msg.cmd = IPMI_GET_DEVICE_ID_CMD;
        msg.data = NULL;
        msg.data_len = 0;
        intf->null_user_handler = device_id_fetcher;
        ipmi_panic_request_and_wait(intf, &addr, &msg);

        if (intf->local_event_generator) {
                /* Request the event receiver from the local MC. */
                msg.netfn = IPMI_NETFN_SENSOR_EVENT_REQUEST;
                msg.cmd = IPMI_GET_EVENT_RECEIVER_CMD;
                msg.data = NULL;
                msg.data_len = 0;
                intf->null_user_handler = event_receiver_fetcher;
                ipmi_panic_request_and_wait(intf, &addr, &msg);
        }
        intf->null_user_handler = NULL;

        /*
         * Validate the event receiver.  The low bit must not
         * be 1 (it must be a valid IPMB address), it cannot
         * be zero, and it must not be my address.
         */
        if (((intf->event_receiver & 1) == 0)
            && (intf->event_receiver != 0)
            && (intf->event_receiver != intf->addrinfo[0].address)) {
                /*
                 * The event receiver is valid, send an IPMB
                 * message.
                 */
                ipmb = (struct ipmi_ipmb_addr *) &addr;
                ipmb->addr_type = IPMI_IPMB_ADDR_TYPE;
                ipmb->channel = 0; /* FIXME - is this right? */
                ipmb->lun = intf->event_receiver_lun;
                ipmb->slave_addr = intf->event_receiver;
        } else if (intf->local_sel_device) {
                /*
                 * The event receiver was not valid (or was
                 * me), but I am an SEL device, just dump it
                 * in my SEL.
                 */
                si = (struct ipmi_system_interface_addr *) &addr;
                si->addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
                si->channel = IPMI_BMC_CHANNEL;
                si->lun = 0;
        } else
                return; /* No where to send the event. */

        msg.netfn = IPMI_NETFN_STORAGE_REQUEST; /* Storage. */
        msg.cmd = IPMI_ADD_SEL_ENTRY_CMD;
        msg.data = data;
        msg.data_len = 16;

        j = 0;
        while (*p) {
                int size = strlen(p);

                if (size > 11)
                        size = 11;
                data[0] = 0;
                data[1] = 0;
                data[2] = 0xf0; /* OEM event without timestamp. */
                data[3] = intf->addrinfo[0].address;
                data[4] = j++; /* sequence # */
                /*
                 * Always give 11 bytes, so strncpy will fill
                 * it with zeroes for me.
                 */
                strncpy(data+5, p, 11);
                p += size;

                ipmi_panic_request_and_wait(intf, &addr, &msg);
        }
}

static int has_panicked;

static int panic_event(struct notifier_block *this,
                       unsigned long         event,
                       void                  *ptr)
{
        struct ipmi_smi *intf;
        struct ipmi_user *user;

        if (has_panicked)
                return NOTIFY_DONE;
        has_panicked = 1;

        /* For every registered interface, set it to run to completion. */
        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
                if (!intf->handlers || intf->intf_num == -1)
                        /* Interface is not ready. */
                        continue;

                if (!intf->handlers->poll)
                        continue;

                /*
                 * If we were interrupted while locking xmit_msgs_lock or
                 * waiting_rcv_msgs_lock, the corresponding list may be
                 * corrupted.  In this case, drop items on the list for
                 * the safety.
                 */
                if (!spin_trylock(&intf->xmit_msgs_lock)) {
                        INIT_LIST_HEAD(&intf->xmit_msgs);
                        INIT_LIST_HEAD(&intf->hp_xmit_msgs);
                } else
                        spin_unlock(&intf->xmit_msgs_lock);

                if (!spin_trylock(&intf->waiting_rcv_msgs_lock))
                        INIT_LIST_HEAD(&intf->waiting_rcv_msgs);
                else
                        spin_unlock(&intf->waiting_rcv_msgs_lock);

                intf->run_to_completion = 1;
                if (intf->handlers->set_run_to_completion)
                        intf->handlers->set_run_to_completion(intf->send_info,
                                                              1);

                list_for_each_entry_rcu(user, &intf->users, link) {
                        if (user->handler->ipmi_panic_handler)
                                user->handler->ipmi_panic_handler(
                                        user->handler_data);
                }

                send_panic_events(intf, ptr);
        }

        return NOTIFY_DONE;
}

static struct notifier_block panic_block = {
        .notifier_call  = panic_event,
        .next           = NULL,
        .priority       = 200   /* priority: INT_MAX >= x >= 0 */
};

static int ipmi_init_msghandler(void)
{
        int rv;

        if (initialized)
                return 0;

        rv = driver_register(&ipmidriver.driver);
        if (rv) {
                pr_err(PFX "Could not register IPMI driver\n");
                return rv;
        }

        pr_info("ipmi message handler version " IPMI_DRIVER_VERSION "\n");

        timer_setup(&ipmi_timer, ipmi_timeout, 0);
        mod_timer(&ipmi_timer, jiffies + IPMI_TIMEOUT_JIFFIES);

        atomic_notifier_chain_register(&panic_notifier_list, &panic_block);

        initialized = 1;

        return 0;
}

static int __init ipmi_init_msghandler_mod(void)
{
        ipmi_init_msghandler();
        return 0;
}

static void __exit cleanup_ipmi(void)
{
        int count;

        if (!initialized)
                return;

        atomic_notifier_chain_unregister(&panic_notifier_list, &panic_block);

        /*
         * This can't be called if any interfaces exist, so no worry
         * about shutting down the interfaces.
         */

        /*
         * Tell the timer to stop, then wait for it to stop.  This
         * avoids problems with race conditions removing the timer
         * here.
         */
        atomic_inc(&stop_operation);
        del_timer_sync(&ipmi_timer);

        driver_unregister(&ipmidriver.driver);

        initialized = 0;

        /* Check for buffer leaks. */
        count = atomic_read(&smi_msg_inuse_count);
        if (count != 0)
                pr_warn(PFX "SMI message count %d at exit\n", count);
        count = atomic_read(&recv_msg_inuse_count);
        if (count != 0)
                pr_warn(PFX "recv message count %d at exit\n", count);
}
module_exit(cleanup_ipmi);

module_init(ipmi_init_msghandler_mod);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Corey Minyard <minyard@mvista.com>");
MODULE_DESCRIPTION("Incoming and outgoing message routing for an IPMI"
                   " interface.");
MODULE_VERSION(IPMI_DRIVER_VERSION);
MODULE_SOFTDEP("post: ipmi_devintf");