xen/time: use READ_ONCE

[linux/fpc-iii.git] / net / rds / rds.h

#ifndef _RDS_RDS_H
#define _RDS_RDS_H

#include <net/sock.h>
#include <linux/scatterlist.h>
#include <linux/highmem.h>
#include <rdma/rdma_cm.h>
#include <linux/mutex.h>
#include <linux/rds.h>
#include <linux/rhashtable.h>

#include "info.h"

/*
 * RDS Network protocol version
 */
#define RDS_PROTOCOL_3_0        0x0300
#define RDS_PROTOCOL_3_1        0x0301
#define RDS_PROTOCOL_VERSION    RDS_PROTOCOL_3_1
#define RDS_PROTOCOL_MAJOR(v)   ((v) >> 8)
#define RDS_PROTOCOL_MINOR(v)   ((v) & 255)
#define RDS_PROTOCOL(maj, min)  (((maj) << 8) | min)

/*
 * XXX randomly chosen, but at least seems to be unused:
 * #               18464-18768 Unassigned
 * We should do better.  We want a reserved port to discourage unpriv'ed
 * userspace from listening.
 */
#define RDS_PORT        18634

#ifdef ATOMIC64_INIT
#define KERNEL_HAS_ATOMIC64
#endif

#ifdef DEBUG
#define rdsdebug(fmt, args...) pr_debug("%s(): " fmt, __func__ , ##args)
#else
/* sigh, pr_debug() causes unused variable warnings */
static inline __printf(1, 2)
void rdsdebug(char *fmt, ...)
{
}
#endif

/* XXX is there one of these somewhere? */
#define ceil(x, y) \
        ({ unsigned long __x = (x), __y = (y); (__x + __y - 1) / __y; })

#define RDS_FRAG_SHIFT  12
#define RDS_FRAG_SIZE   ((unsigned int)(1 << RDS_FRAG_SHIFT))

#define RDS_CONG_MAP_BYTES      (65536 / 8)
#define RDS_CONG_MAP_PAGES      (PAGE_ALIGN(RDS_CONG_MAP_BYTES) / PAGE_SIZE)
#define RDS_CONG_MAP_PAGE_BITS  (PAGE_SIZE * 8)

struct rds_cong_map {
        struct rb_node          m_rb_node;
        __be32                  m_addr;
        wait_queue_head_t       m_waitq;
        struct list_head        m_conn_list;
        unsigned long           m_page_addrs[RDS_CONG_MAP_PAGES];
};


/*
 * This is how we will track the connection state:
 * A connection is always in one of the following
 * states. Updates to the state are atomic and imply
 * a memory barrier.
 */
enum {
        RDS_CONN_DOWN = 0,
        RDS_CONN_CONNECTING,
        RDS_CONN_DISCONNECTING,
        RDS_CONN_UP,
        RDS_CONN_ERROR,
};

/* Bits for c_flags */
#define RDS_LL_SEND_FULL        0
#define RDS_RECONNECT_PENDING   1
#define RDS_IN_XMIT             2
#define RDS_RECV_REFILL         3

struct rds_connection {
        struct hlist_node       c_hash_node;
        __be32                  c_laddr;
        __be32                  c_faddr;
        unsigned int            c_loopback:1,
                                c_outgoing:1,
                                c_pad_to_32:30;
        struct rds_connection   *c_passive;

        struct rds_cong_map     *c_lcong;
        struct rds_cong_map     *c_fcong;

        struct rds_message      *c_xmit_rm;
        unsigned long           c_xmit_sg;
        unsigned int            c_xmit_hdr_off;
        unsigned int            c_xmit_data_off;
        unsigned int            c_xmit_atomic_sent;
        unsigned int            c_xmit_rdma_sent;
        unsigned int            c_xmit_data_sent;

        spinlock_t              c_lock;         /* protect msg queues */
        u64                     c_next_tx_seq;
        struct list_head        c_send_queue;
        struct list_head        c_retrans;

        u64                     c_next_rx_seq;

        struct rds_transport    *c_trans;
        void                    *c_transport_data;

        atomic_t                c_state;
        unsigned long           c_send_gen;
        unsigned long           c_flags;
        unsigned long           c_reconnect_jiffies;
        struct delayed_work     c_send_w;
        struct delayed_work     c_recv_w;
        struct delayed_work     c_conn_w;
        struct work_struct      c_down_w;
        struct mutex            c_cm_lock;      /* protect conn state & cm */
        wait_queue_head_t       c_waitq;

        struct list_head        c_map_item;
        unsigned long           c_map_queued;

        unsigned int            c_unacked_packets;
        unsigned int            c_unacked_bytes;

        /* Protocol version */
        unsigned int            c_version;
        possible_net_t          c_net;
};

static inline
struct net *rds_conn_net(struct rds_connection *conn)
{
        return read_pnet(&conn->c_net);
}

static inline
void rds_conn_net_set(struct rds_connection *conn, struct net *net)
{
        write_pnet(&conn->c_net, net);
}

#define RDS_FLAG_CONG_BITMAP    0x01
#define RDS_FLAG_ACK_REQUIRED   0x02
#define RDS_FLAG_RETRANSMITTED  0x04
#define RDS_MAX_ADV_CREDIT      255

/*
 * Maximum space available for extension headers.
 */
#define RDS_HEADER_EXT_SPACE    16

struct rds_header {
        __be64  h_sequence;
        __be64  h_ack;
        __be32  h_len;
        __be16  h_sport;
        __be16  h_dport;
        u8      h_flags;
        u8      h_credit;
        u8      h_padding[4];
        __sum16 h_csum;

        u8      h_exthdr[RDS_HEADER_EXT_SPACE];
};

/*
 * Reserved - indicates end of extensions
 */
#define RDS_EXTHDR_NONE         0

/*
 * This extension header is included in the very
 * first message that is sent on a new connection,
 * and identifies the protocol level. This will help
 * rolling updates if a future change requires breaking
 * the protocol.
 * NB: This is no longer true for IB, where we do a version
 * negotiation during the connection setup phase (protocol
 * version information is included in the RDMA CM private data).
 */
#define RDS_EXTHDR_VERSION      1
struct rds_ext_header_version {
        __be32                  h_version;
};

/*
 * This extension header is included in the RDS message
 * chasing an RDMA operation.
 */
#define RDS_EXTHDR_RDMA         2
struct rds_ext_header_rdma {
        __be32                  h_rdma_rkey;
};

/*
 * This extension header tells the peer about the
 * destination <R_Key,offset> of the requested RDMA
 * operation.
 */
#define RDS_EXTHDR_RDMA_DEST    3
struct rds_ext_header_rdma_dest {
        __be32                  h_rdma_rkey;
        __be32                  h_rdma_offset;
};

#define __RDS_EXTHDR_MAX        16 /* for now */

struct rds_incoming {
        atomic_t                i_refcount;
        struct list_head        i_item;
        struct rds_connection   *i_conn;
        struct rds_header       i_hdr;
        unsigned long           i_rx_jiffies;
        __be32                  i_saddr;

        rds_rdma_cookie_t       i_rdma_cookie;
};

struct rds_mr {
        struct rb_node          r_rb_node;
        atomic_t                r_refcount;
        u32                     r_key;

        /* A copy of the creation flags */
        unsigned int            r_use_once:1;
        unsigned int            r_invalidate:1;
        unsigned int            r_write:1;

        /* This is for RDS_MR_DEAD.
         * It would be nice & consistent to make this part of the above
         * bit field here, but we need to use test_and_set_bit.
         */
        unsigned long           r_state;
        struct rds_sock         *r_sock; /* back pointer to the socket that owns us */
        struct rds_transport    *r_trans;
        void                    *r_trans_private;
};

/* Flags for mr->r_state */
#define RDS_MR_DEAD             0

static inline rds_rdma_cookie_t rds_rdma_make_cookie(u32 r_key, u32 offset)
{
        return r_key | (((u64) offset) << 32);
}

static inline u32 rds_rdma_cookie_key(rds_rdma_cookie_t cookie)
{
        return cookie;
}

static inline u32 rds_rdma_cookie_offset(rds_rdma_cookie_t cookie)
{
        return cookie >> 32;
}

/* atomic operation types */
#define RDS_ATOMIC_TYPE_CSWP            0
#define RDS_ATOMIC_TYPE_FADD            1

/*
 * m_sock_item and m_conn_item are on lists that are serialized under
 * conn->c_lock.  m_sock_item has additional meaning in that once it is empty
 * the message will not be put back on the retransmit list after being sent.
 * messages that are canceled while being sent rely on this.
 *
 * m_inc is used by loopback so that it can pass an incoming message straight
 * back up into the rx path.  It embeds a wire header which is also used by
 * the send path, which is kind of awkward.
 *
 * m_sock_item indicates the message's presence on a socket's send or receive
 * queue.  m_rs will point to that socket.
 *
 * m_daddr is used by cancellation to prune messages to a given destination.
 *
 * The RDS_MSG_ON_SOCK and RDS_MSG_ON_CONN flags are used to avoid lock
 * nesting.  As paths iterate over messages on a sock, or conn, they must
 * also lock the conn, or sock, to remove the message from those lists too.
 * Testing the flag to determine if the message is still on the lists lets
 * us avoid testing the list_head directly.  That means each path can use
 * the message's list_head to keep it on a local list while juggling locks
 * without confusing the other path.
 *
 * m_ack_seq is an optional field set by transports who need a different
 * sequence number range to invalidate.  They can use this in a callback
 * that they pass to rds_send_drop_acked() to see if each message has been
 * acked.  The HAS_ACK_SEQ flag can be used to detect messages which haven't
 * had ack_seq set yet.
 */
#define RDS_MSG_ON_SOCK         1
#define RDS_MSG_ON_CONN         2
#define RDS_MSG_HAS_ACK_SEQ     3
#define RDS_MSG_ACK_REQUIRED    4
#define RDS_MSG_RETRANSMITTED   5
#define RDS_MSG_MAPPED          6
#define RDS_MSG_PAGEVEC         7

struct rds_message {
        atomic_t                m_refcount;
        struct list_head        m_sock_item;
        struct list_head        m_conn_item;
        struct rds_incoming     m_inc;
        u64                     m_ack_seq;
        __be32                  m_daddr;
        unsigned long           m_flags;

        /* Never access m_rs without holding m_rs_lock.
         * Lock nesting is
         *  rm->m_rs_lock
         *   -> rs->rs_lock
         */
        spinlock_t              m_rs_lock;
        wait_queue_head_t       m_flush_wait;

        struct rds_sock         *m_rs;

        /* cookie to send to remote, in rds header */
        rds_rdma_cookie_t       m_rdma_cookie;

        unsigned int            m_used_sgs;
        unsigned int            m_total_sgs;

        void                    *m_final_op;

        struct {
                struct rm_atomic_op {
                        int                     op_type;
                        union {
                                struct {
                                        uint64_t        compare;
                                        uint64_t        swap;
                                        uint64_t        compare_mask;
                                        uint64_t        swap_mask;
                                } op_m_cswp;
                                struct {
                                        uint64_t        add;
                                        uint64_t        nocarry_mask;
                                } op_m_fadd;
                        };

                        u32                     op_rkey;
                        u64                     op_remote_addr;
                        unsigned int            op_notify:1;
                        unsigned int            op_recverr:1;
                        unsigned int            op_mapped:1;
                        unsigned int            op_silent:1;
                        unsigned int            op_active:1;
                        struct scatterlist      *op_sg;
                        struct rds_notifier     *op_notifier;

                        struct rds_mr           *op_rdma_mr;
                } atomic;
                struct rm_rdma_op {
                        u32                     op_rkey;
                        u64                     op_remote_addr;
                        unsigned int            op_write:1;
                        unsigned int            op_fence:1;
                        unsigned int            op_notify:1;
                        unsigned int            op_recverr:1;
                        unsigned int            op_mapped:1;
                        unsigned int            op_silent:1;
                        unsigned int            op_active:1;
                        unsigned int            op_bytes;
                        unsigned int            op_nents;
                        unsigned int            op_count;
                        struct scatterlist      *op_sg;
                        struct rds_notifier     *op_notifier;

                        struct rds_mr           *op_rdma_mr;
                } rdma;
                struct rm_data_op {
                        unsigned int            op_active:1;
                        unsigned int            op_nents;
                        unsigned int            op_count;
                        unsigned int            op_dmasg;
                        unsigned int            op_dmaoff;
                        struct scatterlist      *op_sg;
                } data;
        };
};

/*
 * The RDS notifier is used (optionally) to tell the application about
 * completed RDMA operations. Rather than keeping the whole rds message
 * around on the queue, we allocate a small notifier that is put on the
 * socket's notifier_list. Notifications are delivered to the application
 * through control messages.
 */
struct rds_notifier {
        struct list_head        n_list;
        uint64_t                n_user_token;
        int                     n_status;
};

/**
 * struct rds_transport -  transport specific behavioural hooks
 *
 * @xmit: .xmit is called by rds_send_xmit() to tell the transport to send
 *        part of a message.  The caller serializes on the send_sem so this
 *        doesn't need to be reentrant for a given conn.  The header must be
 *        sent before the data payload.  .xmit must be prepared to send a
 *        message with no data payload.  .xmit should return the number of
 *        bytes that were sent down the connection, including header bytes.
 *        Returning 0 tells the caller that it doesn't need to perform any
 *        additional work now.  This is usually the case when the transport has
 *        filled the sending queue for its connection and will handle
 *        triggering the rds thread to continue the send when space becomes
 *        available.  Returning -EAGAIN tells the caller to retry the send
 *        immediately.  Returning -ENOMEM tells the caller to retry the send at
 *        some point in the future.
 *
 * @conn_shutdown: conn_shutdown stops traffic on the given connection.  Once
 *                 it returns the connection can not call rds_recv_incoming().
 *                 This will only be called once after conn_connect returns
 *                 non-zero success and will The caller serializes this with
 *                 the send and connecting paths (xmit_* and conn_*).  The
 *                 transport is responsible for other serialization, including
 *                 rds_recv_incoming().  This is called in process context but
 *                 should try hard not to block.
 */

struct rds_transport {
        char                    t_name[TRANSNAMSIZ];
        struct list_head        t_item;
        struct module           *t_owner;
        unsigned int            t_prefer_loopback:1;
        unsigned int            t_type;

        int (*laddr_check)(struct net *net, __be32 addr);
        int (*conn_alloc)(struct rds_connection *conn, gfp_t gfp);
        void (*conn_free)(void *data);
        int (*conn_connect)(struct rds_connection *conn);
        void (*conn_shutdown)(struct rds_connection *conn);
        void (*xmit_prepare)(struct rds_connection *conn);
        void (*xmit_complete)(struct rds_connection *conn);
        int (*xmit)(struct rds_connection *conn, struct rds_message *rm,
                    unsigned int hdr_off, unsigned int sg, unsigned int off);
        int (*xmit_rdma)(struct rds_connection *conn, struct rm_rdma_op *op);
        int (*xmit_atomic)(struct rds_connection *conn, struct rm_atomic_op *op);
        int (*recv)(struct rds_connection *conn);
        int (*inc_copy_to_user)(struct rds_incoming *inc, struct iov_iter *to);
        void (*inc_free)(struct rds_incoming *inc);

        int (*cm_handle_connect)(struct rdma_cm_id *cm_id,
                                 struct rdma_cm_event *event);
        int (*cm_initiate_connect)(struct rdma_cm_id *cm_id);
        void (*cm_connect_complete)(struct rds_connection *conn,
                                    struct rdma_cm_event *event);

        unsigned int (*stats_info_copy)(struct rds_info_iterator *iter,
                                        unsigned int avail);
        void (*exit)(void);
        void *(*get_mr)(struct scatterlist *sg, unsigned long nr_sg,
                        struct rds_sock *rs, u32 *key_ret);
        void (*sync_mr)(void *trans_private, int direction);
        void (*free_mr)(void *trans_private, int invalidate);
        void (*flush_mrs)(void);
};

struct rds_sock {
        struct sock             rs_sk;

        u64                     rs_user_addr;
        u64                     rs_user_bytes;

        /*
         * bound_addr used for both incoming and outgoing, no INADDR_ANY
         * support.
         */
        struct rhash_head       rs_bound_node;
        u64                     rs_bound_key;
        __be32                  rs_bound_addr;
        __be32                  rs_conn_addr;
        __be16                  rs_bound_port;
        __be16                  rs_conn_port;
        struct rds_transport    *rs_transport;

        /*
         * rds_sendmsg caches the conn it used the last time around.
         * This helps avoid costly lookups.
         */
        struct rds_connection   *rs_conn;

        /* flag indicating we were congested or not */
        int                     rs_congested;
        /* seen congestion (ENOBUFS) when sending? */
        int                     rs_seen_congestion;

        /* rs_lock protects all these adjacent members before the newline */
        spinlock_t              rs_lock;
        struct list_head        rs_send_queue;
        u32                     rs_snd_bytes;
        int                     rs_rcv_bytes;
        struct list_head        rs_notify_queue;        /* currently used for failed RDMAs */

        /* Congestion wake_up. If rs_cong_monitor is set, we use cong_mask
         * to decide whether the application should be woken up.
         * If not set, we use rs_cong_track to find out whether a cong map
         * update arrived.
         */
        uint64_t                rs_cong_mask;
        uint64_t                rs_cong_notify;
        struct list_head        rs_cong_list;
        unsigned long           rs_cong_track;

        /*
         * rs_recv_lock protects the receive queue, and is
         * used to serialize with rds_release.
         */
        rwlock_t                rs_recv_lock;
        struct list_head        rs_recv_queue;

        /* just for stats reporting */
        struct list_head        rs_item;

        /* these have their own lock */
        spinlock_t              rs_rdma_lock;
        struct rb_root          rs_rdma_keys;

        /* Socket options - in case there will be more */
        unsigned char           rs_recverr,
                                rs_cong_monitor;
};

static inline struct rds_sock *rds_sk_to_rs(const struct sock *sk)
{
        return container_of(sk, struct rds_sock, rs_sk);
}
static inline struct sock *rds_rs_to_sk(struct rds_sock *rs)
{
        return &rs->rs_sk;
}

/*
 * The stack assigns sk_sndbuf and sk_rcvbuf to twice the specified value
 * to account for overhead.  We don't account for overhead, we just apply
 * the number of payload bytes to the specified value.
 */
static inline int rds_sk_sndbuf(struct rds_sock *rs)
{
        return rds_rs_to_sk(rs)->sk_sndbuf / 2;
}
static inline int rds_sk_rcvbuf(struct rds_sock *rs)
{
        return rds_rs_to_sk(rs)->sk_rcvbuf / 2;
}

struct rds_statistics {
        uint64_t        s_conn_reset;
        uint64_t        s_recv_drop_bad_checksum;
        uint64_t        s_recv_drop_old_seq;
        uint64_t        s_recv_drop_no_sock;
        uint64_t        s_recv_drop_dead_sock;
        uint64_t        s_recv_deliver_raced;
        uint64_t        s_recv_delivered;
        uint64_t        s_recv_queued;
        uint64_t        s_recv_immediate_retry;
        uint64_t        s_recv_delayed_retry;
        uint64_t        s_recv_ack_required;
        uint64_t        s_recv_rdma_bytes;
        uint64_t        s_recv_ping;
        uint64_t        s_send_queue_empty;
        uint64_t        s_send_queue_full;
        uint64_t        s_send_lock_contention;
        uint64_t        s_send_lock_queue_raced;
        uint64_t        s_send_immediate_retry;
        uint64_t        s_send_delayed_retry;
        uint64_t        s_send_drop_acked;
        uint64_t        s_send_ack_required;
        uint64_t        s_send_queued;
        uint64_t        s_send_rdma;
        uint64_t        s_send_rdma_bytes;
        uint64_t        s_send_pong;
        uint64_t        s_page_remainder_hit;
        uint64_t        s_page_remainder_miss;
        uint64_t        s_copy_to_user;
        uint64_t        s_copy_from_user;
        uint64_t        s_cong_update_queued;
        uint64_t        s_cong_update_received;
        uint64_t        s_cong_send_error;
        uint64_t        s_cong_send_blocked;
};

/* af_rds.c */
void rds_sock_addref(struct rds_sock *rs);
void rds_sock_put(struct rds_sock *rs);
void rds_wake_sk_sleep(struct rds_sock *rs);
static inline void __rds_wake_sk_sleep(struct sock *sk)
{
        wait_queue_head_t *waitq = sk_sleep(sk);

        if (!sock_flag(sk, SOCK_DEAD) && waitq)
                wake_up(waitq);
}
extern wait_queue_head_t rds_poll_waitq;


/* bind.c */
int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len);
void rds_remove_bound(struct rds_sock *rs);
struct rds_sock *rds_find_bound(__be32 addr, __be16 port);
int rds_bind_lock_init(void);
void rds_bind_lock_destroy(void);

/* cong.c */
int rds_cong_get_maps(struct rds_connection *conn);
void rds_cong_add_conn(struct rds_connection *conn);
void rds_cong_remove_conn(struct rds_connection *conn);
void rds_cong_set_bit(struct rds_cong_map *map, __be16 port);
void rds_cong_clear_bit(struct rds_cong_map *map, __be16 port);
int rds_cong_wait(struct rds_cong_map *map, __be16 port, int nonblock, struct rds_sock *rs);
void rds_cong_queue_updates(struct rds_cong_map *map);
void rds_cong_map_updated(struct rds_cong_map *map, uint64_t);
int rds_cong_updated_since(unsigned long *recent);
void rds_cong_add_socket(struct rds_sock *);
void rds_cong_remove_socket(struct rds_sock *);
void rds_cong_exit(void);
struct rds_message *rds_cong_update_alloc(struct rds_connection *conn);

/* conn.c */
int rds_conn_init(void);
void rds_conn_exit(void);
struct rds_connection *rds_conn_create(struct net *net,
                                       __be32 laddr, __be32 faddr,
                                       struct rds_transport *trans, gfp_t gfp);
struct rds_connection *rds_conn_create_outgoing(struct net *net,
                                                __be32 laddr, __be32 faddr,
                               struct rds_transport *trans, gfp_t gfp);
void rds_conn_shutdown(struct rds_connection *conn);
void rds_conn_destroy(struct rds_connection *conn);
void rds_conn_drop(struct rds_connection *conn);
void rds_conn_connect_if_down(struct rds_connection *conn);
void rds_for_each_conn_info(struct socket *sock, unsigned int len,
                          struct rds_info_iterator *iter,
                          struct rds_info_lengths *lens,
                          int (*visitor)(struct rds_connection *, void *),
                          size_t item_len);
__printf(2, 3)
void __rds_conn_error(struct rds_connection *conn, const char *, ...);
#define rds_conn_error(conn, fmt...) \
        __rds_conn_error(conn, KERN_WARNING "RDS: " fmt)

static inline int
rds_conn_transition(struct rds_connection *conn, int old, int new)
{
        return atomic_cmpxchg(&conn->c_state, old, new) == old;
}

static inline int
rds_conn_state(struct rds_connection *conn)
{
        return atomic_read(&conn->c_state);
}

static inline int
rds_conn_up(struct rds_connection *conn)
{
        return atomic_read(&conn->c_state) == RDS_CONN_UP;
}

static inline int
rds_conn_connecting(struct rds_connection *conn)
{
        return atomic_read(&conn->c_state) == RDS_CONN_CONNECTING;
}

/* message.c */
struct rds_message *rds_message_alloc(unsigned int nents, gfp_t gfp);
struct scatterlist *rds_message_alloc_sgs(struct rds_message *rm, int nents);
int rds_message_copy_from_user(struct rds_message *rm, struct iov_iter *from);
struct rds_message *rds_message_map_pages(unsigned long *page_addrs, unsigned int total_len);
void rds_message_populate_header(struct rds_header *hdr, __be16 sport,
                                 __be16 dport, u64 seq);
int rds_message_add_extension(struct rds_header *hdr,
                              unsigned int type, const void *data, unsigned int len);
int rds_message_next_extension(struct rds_header *hdr,
                               unsigned int *pos, void *buf, unsigned int *buflen);
int rds_message_add_rdma_dest_extension(struct rds_header *hdr, u32 r_key, u32 offset);
int rds_message_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to);
void rds_message_inc_free(struct rds_incoming *inc);
void rds_message_addref(struct rds_message *rm);
void rds_message_put(struct rds_message *rm);
void rds_message_wait(struct rds_message *rm);
void rds_message_unmapped(struct rds_message *rm);

static inline void rds_message_make_checksum(struct rds_header *hdr)
{
        hdr->h_csum = 0;
        hdr->h_csum = ip_fast_csum((void *) hdr, sizeof(*hdr) >> 2);
}

static inline int rds_message_verify_checksum(const struct rds_header *hdr)
{
        return !hdr->h_csum || ip_fast_csum((void *) hdr, sizeof(*hdr) >> 2) == 0;
}


/* page.c */
int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
                             gfp_t gfp);
int rds_page_copy_user(struct page *page, unsigned long offset,
                       void __user *ptr, unsigned long bytes,
                       int to_user);
#define rds_page_copy_to_user(page, offset, ptr, bytes) \
        rds_page_copy_user(page, offset, ptr, bytes, 1)
#define rds_page_copy_from_user(page, offset, ptr, bytes) \
        rds_page_copy_user(page, offset, ptr, bytes, 0)
void rds_page_exit(void);

/* recv.c */
void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
                  __be32 saddr);
void rds_inc_put(struct rds_incoming *inc);
void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
                       struct rds_incoming *inc, gfp_t gfp);
int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
                int msg_flags);
void rds_clear_recv_queue(struct rds_sock *rs);
int rds_notify_queue_get(struct rds_sock *rs, struct msghdr *msg);
void rds_inc_info_copy(struct rds_incoming *inc,
                       struct rds_info_iterator *iter,
                       __be32 saddr, __be32 daddr, int flip);

/* send.c */
int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len);
void rds_send_reset(struct rds_connection *conn);
int rds_send_xmit(struct rds_connection *conn);
struct sockaddr_in;
void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest);
typedef int (*is_acked_func)(struct rds_message *rm, uint64_t ack);
void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
                         is_acked_func is_acked);
int rds_send_pong(struct rds_connection *conn, __be16 dport);
struct rds_message *rds_send_get_message(struct rds_connection *,
                                         struct rm_rdma_op *);

/* rdma.c */
void rds_rdma_unuse(struct rds_sock *rs, u32 r_key, int force);
int rds_get_mr(struct rds_sock *rs, char __user *optval, int optlen);
int rds_get_mr_for_dest(struct rds_sock *rs, char __user *optval, int optlen);
int rds_free_mr(struct rds_sock *rs, char __user *optval, int optlen);
void rds_rdma_drop_keys(struct rds_sock *rs);
int rds_rdma_extra_size(struct rds_rdma_args *args);
int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
                          struct cmsghdr *cmsg);
int rds_cmsg_rdma_dest(struct rds_sock *rs, struct rds_message *rm,
                          struct cmsghdr *cmsg);
int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
                          struct cmsghdr *cmsg);
int rds_cmsg_rdma_map(struct rds_sock *rs, struct rds_message *rm,
                          struct cmsghdr *cmsg);
void rds_rdma_free_op(struct rm_rdma_op *ro);
void rds_atomic_free_op(struct rm_atomic_op *ao);
void rds_rdma_send_complete(struct rds_message *rm, int wc_status);
void rds_atomic_send_complete(struct rds_message *rm, int wc_status);
int rds_cmsg_atomic(struct rds_sock *rs, struct rds_message *rm,
                    struct cmsghdr *cmsg);

void __rds_put_mr_final(struct rds_mr *mr);
static inline void rds_mr_put(struct rds_mr *mr)
{
        if (atomic_dec_and_test(&mr->r_refcount))
                __rds_put_mr_final(mr);
}

/* stats.c */
DECLARE_PER_CPU_SHARED_ALIGNED(struct rds_statistics, rds_stats);
#define rds_stats_inc_which(which, member) do {         \
        per_cpu(which, get_cpu()).member++;             \
        put_cpu();                                      \
} while (0)
#define rds_stats_inc(member) rds_stats_inc_which(rds_stats, member)
#define rds_stats_add_which(which, member, count) do {          \
        per_cpu(which, get_cpu()).member += count;      \
        put_cpu();                                      \
} while (0)
#define rds_stats_add(member, count) rds_stats_add_which(rds_stats, member, count)
int rds_stats_init(void);
void rds_stats_exit(void);
void rds_stats_info_copy(struct rds_info_iterator *iter,
                         uint64_t *values, const char *const *names,
                         size_t nr);

/* sysctl.c */
int rds_sysctl_init(void);
void rds_sysctl_exit(void);
extern unsigned long rds_sysctl_sndbuf_min;
extern unsigned long rds_sysctl_sndbuf_default;
extern unsigned long rds_sysctl_sndbuf_max;
extern unsigned long rds_sysctl_reconnect_min_jiffies;
extern unsigned long rds_sysctl_reconnect_max_jiffies;
extern unsigned int  rds_sysctl_max_unacked_packets;
extern unsigned int  rds_sysctl_max_unacked_bytes;
extern unsigned int  rds_sysctl_ping_enable;
extern unsigned long rds_sysctl_trace_flags;
extern unsigned int  rds_sysctl_trace_level;

/* threads.c */
int rds_threads_init(void);
void rds_threads_exit(void);
extern struct workqueue_struct *rds_wq;
void rds_queue_reconnect(struct rds_connection *conn);
void rds_connect_worker(struct work_struct *);
void rds_shutdown_worker(struct work_struct *);
void rds_send_worker(struct work_struct *);
void rds_recv_worker(struct work_struct *);
void rds_connect_complete(struct rds_connection *conn);

/* transport.c */
int rds_trans_register(struct rds_transport *trans);
void rds_trans_unregister(struct rds_transport *trans);
struct rds_transport *rds_trans_get_preferred(struct net *net, __be32 addr);
void rds_trans_put(struct rds_transport *trans);
unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
                                       unsigned int avail);
struct rds_transport *rds_trans_get(int t_type);
int rds_trans_init(void);
void rds_trans_exit(void);

#endif