Linux 4.2.1

[linux/fpc-iii.git] / drivers / infiniband / core / uverbs_main.c

/*
 * Copyright (c) 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005, 2006 Cisco Systems.  All rights reserved.
 * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
 * Copyright (c) 2005 Voltaire, Inc. All rights reserved.
 * Copyright (c) 2005 PathScale, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/cdev.h>
#include <linux/anon_inodes.h>
#include <linux/slab.h>

#include <asm/uaccess.h>

#include "uverbs.h"

MODULE_AUTHOR("Roland Dreier");
MODULE_DESCRIPTION("InfiniBand userspace verbs access");
MODULE_LICENSE("Dual BSD/GPL");

enum {
        IB_UVERBS_MAJOR       = 231,
        IB_UVERBS_BASE_MINOR  = 192,
        IB_UVERBS_MAX_DEVICES = 32
};

#define IB_UVERBS_BASE_DEV      MKDEV(IB_UVERBS_MAJOR, IB_UVERBS_BASE_MINOR)

static struct class *uverbs_class;

DEFINE_SPINLOCK(ib_uverbs_idr_lock);
DEFINE_IDR(ib_uverbs_pd_idr);
DEFINE_IDR(ib_uverbs_mr_idr);
DEFINE_IDR(ib_uverbs_mw_idr);
DEFINE_IDR(ib_uverbs_ah_idr);
DEFINE_IDR(ib_uverbs_cq_idr);
DEFINE_IDR(ib_uverbs_qp_idr);
DEFINE_IDR(ib_uverbs_srq_idr);
DEFINE_IDR(ib_uverbs_xrcd_idr);
DEFINE_IDR(ib_uverbs_rule_idr);

static DEFINE_SPINLOCK(map_lock);
static DECLARE_BITMAP(dev_map, IB_UVERBS_MAX_DEVICES);

static ssize_t (*uverbs_cmd_table[])(struct ib_uverbs_file *file,
                                     const char __user *buf, int in_len,
                                     int out_len) = {
        [IB_USER_VERBS_CMD_GET_CONTEXT]         = ib_uverbs_get_context,
        [IB_USER_VERBS_CMD_QUERY_DEVICE]        = ib_uverbs_query_device,
        [IB_USER_VERBS_CMD_QUERY_PORT]          = ib_uverbs_query_port,
        [IB_USER_VERBS_CMD_ALLOC_PD]            = ib_uverbs_alloc_pd,
        [IB_USER_VERBS_CMD_DEALLOC_PD]          = ib_uverbs_dealloc_pd,
        [IB_USER_VERBS_CMD_REG_MR]              = ib_uverbs_reg_mr,
        [IB_USER_VERBS_CMD_REREG_MR]            = ib_uverbs_rereg_mr,
        [IB_USER_VERBS_CMD_DEREG_MR]            = ib_uverbs_dereg_mr,
        [IB_USER_VERBS_CMD_ALLOC_MW]            = ib_uverbs_alloc_mw,
        [IB_USER_VERBS_CMD_DEALLOC_MW]          = ib_uverbs_dealloc_mw,
        [IB_USER_VERBS_CMD_CREATE_COMP_CHANNEL] = ib_uverbs_create_comp_channel,
        [IB_USER_VERBS_CMD_CREATE_CQ]           = ib_uverbs_create_cq,
        [IB_USER_VERBS_CMD_RESIZE_CQ]           = ib_uverbs_resize_cq,
        [IB_USER_VERBS_CMD_POLL_CQ]             = ib_uverbs_poll_cq,
        [IB_USER_VERBS_CMD_REQ_NOTIFY_CQ]       = ib_uverbs_req_notify_cq,
        [IB_USER_VERBS_CMD_DESTROY_CQ]          = ib_uverbs_destroy_cq,
        [IB_USER_VERBS_CMD_CREATE_QP]           = ib_uverbs_create_qp,
        [IB_USER_VERBS_CMD_QUERY_QP]            = ib_uverbs_query_qp,
        [IB_USER_VERBS_CMD_MODIFY_QP]           = ib_uverbs_modify_qp,
        [IB_USER_VERBS_CMD_DESTROY_QP]          = ib_uverbs_destroy_qp,
        [IB_USER_VERBS_CMD_POST_SEND]           = ib_uverbs_post_send,
        [IB_USER_VERBS_CMD_POST_RECV]           = ib_uverbs_post_recv,
        [IB_USER_VERBS_CMD_POST_SRQ_RECV]       = ib_uverbs_post_srq_recv,
        [IB_USER_VERBS_CMD_CREATE_AH]           = ib_uverbs_create_ah,
        [IB_USER_VERBS_CMD_DESTROY_AH]          = ib_uverbs_destroy_ah,
        [IB_USER_VERBS_CMD_ATTACH_MCAST]        = ib_uverbs_attach_mcast,
        [IB_USER_VERBS_CMD_DETACH_MCAST]        = ib_uverbs_detach_mcast,
        [IB_USER_VERBS_CMD_CREATE_SRQ]          = ib_uverbs_create_srq,
        [IB_USER_VERBS_CMD_MODIFY_SRQ]          = ib_uverbs_modify_srq,
        [IB_USER_VERBS_CMD_QUERY_SRQ]           = ib_uverbs_query_srq,
        [IB_USER_VERBS_CMD_DESTROY_SRQ]         = ib_uverbs_destroy_srq,
        [IB_USER_VERBS_CMD_OPEN_XRCD]           = ib_uverbs_open_xrcd,
        [IB_USER_VERBS_CMD_CLOSE_XRCD]          = ib_uverbs_close_xrcd,
        [IB_USER_VERBS_CMD_CREATE_XSRQ]         = ib_uverbs_create_xsrq,
        [IB_USER_VERBS_CMD_OPEN_QP]             = ib_uverbs_open_qp,
};

static int (*uverbs_ex_cmd_table[])(struct ib_uverbs_file *file,
                                    struct ib_udata *ucore,
                                    struct ib_udata *uhw) = {
        [IB_USER_VERBS_EX_CMD_CREATE_FLOW]      = ib_uverbs_ex_create_flow,
        [IB_USER_VERBS_EX_CMD_DESTROY_FLOW]     = ib_uverbs_ex_destroy_flow,
        [IB_USER_VERBS_EX_CMD_QUERY_DEVICE]     = ib_uverbs_ex_query_device,
        [IB_USER_VERBS_EX_CMD_CREATE_CQ]        = ib_uverbs_ex_create_cq,
};

static void ib_uverbs_add_one(struct ib_device *device);
static void ib_uverbs_remove_one(struct ib_device *device);

static void ib_uverbs_release_dev(struct kref *ref)
{
        struct ib_uverbs_device *dev =
                container_of(ref, struct ib_uverbs_device, ref);

        complete(&dev->comp);
}

static void ib_uverbs_release_event_file(struct kref *ref)
{
        struct ib_uverbs_event_file *file =
                container_of(ref, struct ib_uverbs_event_file, ref);

        kfree(file);
}

void ib_uverbs_release_ucq(struct ib_uverbs_file *file,
                          struct ib_uverbs_event_file *ev_file,
                          struct ib_ucq_object *uobj)
{
        struct ib_uverbs_event *evt, *tmp;

        if (ev_file) {
                spin_lock_irq(&ev_file->lock);
                list_for_each_entry_safe(evt, tmp, &uobj->comp_list, obj_list) {
                        list_del(&evt->list);
                        kfree(evt);
                }
                spin_unlock_irq(&ev_file->lock);

                kref_put(&ev_file->ref, ib_uverbs_release_event_file);
        }

        spin_lock_irq(&file->async_file->lock);
        list_for_each_entry_safe(evt, tmp, &uobj->async_list, obj_list) {
                list_del(&evt->list);
                kfree(evt);
        }
        spin_unlock_irq(&file->async_file->lock);
}

void ib_uverbs_release_uevent(struct ib_uverbs_file *file,
                              struct ib_uevent_object *uobj)
{
        struct ib_uverbs_event *evt, *tmp;

        spin_lock_irq(&file->async_file->lock);
        list_for_each_entry_safe(evt, tmp, &uobj->event_list, obj_list) {
                list_del(&evt->list);
                kfree(evt);
        }
        spin_unlock_irq(&file->async_file->lock);
}

static void ib_uverbs_detach_umcast(struct ib_qp *qp,
                                    struct ib_uqp_object *uobj)
{
        struct ib_uverbs_mcast_entry *mcast, *tmp;

        list_for_each_entry_safe(mcast, tmp, &uobj->mcast_list, list) {
                ib_detach_mcast(qp, &mcast->gid, mcast->lid);
                list_del(&mcast->list);
                kfree(mcast);
        }
}

static int ib_uverbs_cleanup_ucontext(struct ib_uverbs_file *file,
                                      struct ib_ucontext *context)
{
        struct ib_uobject *uobj, *tmp;

        if (!context)
                return 0;

        context->closing = 1;

        list_for_each_entry_safe(uobj, tmp, &context->ah_list, list) {
                struct ib_ah *ah = uobj->object;

                idr_remove_uobj(&ib_uverbs_ah_idr, uobj);
                ib_destroy_ah(ah);
                kfree(uobj);
        }

        /* Remove MWs before QPs, in order to support type 2A MWs. */
        list_for_each_entry_safe(uobj, tmp, &context->mw_list, list) {
                struct ib_mw *mw = uobj->object;

                idr_remove_uobj(&ib_uverbs_mw_idr, uobj);
                ib_dealloc_mw(mw);
                kfree(uobj);
        }

        list_for_each_entry_safe(uobj, tmp, &context->rule_list, list) {
                struct ib_flow *flow_id = uobj->object;

                idr_remove_uobj(&ib_uverbs_rule_idr, uobj);
                ib_destroy_flow(flow_id);
                kfree(uobj);
        }

        list_for_each_entry_safe(uobj, tmp, &context->qp_list, list) {
                struct ib_qp *qp = uobj->object;
                struct ib_uqp_object *uqp =
                        container_of(uobj, struct ib_uqp_object, uevent.uobject);

                idr_remove_uobj(&ib_uverbs_qp_idr, uobj);
                if (qp != qp->real_qp) {
                        ib_close_qp(qp);
                } else {
                        ib_uverbs_detach_umcast(qp, uqp);
                        ib_destroy_qp(qp);
                }
                ib_uverbs_release_uevent(file, &uqp->uevent);
                kfree(uqp);
        }

        list_for_each_entry_safe(uobj, tmp, &context->srq_list, list) {
                struct ib_srq *srq = uobj->object;
                struct ib_uevent_object *uevent =
                        container_of(uobj, struct ib_uevent_object, uobject);

                idr_remove_uobj(&ib_uverbs_srq_idr, uobj);
                ib_destroy_srq(srq);
                ib_uverbs_release_uevent(file, uevent);
                kfree(uevent);
        }

        list_for_each_entry_safe(uobj, tmp, &context->cq_list, list) {
                struct ib_cq *cq = uobj->object;
                struct ib_uverbs_event_file *ev_file = cq->cq_context;
                struct ib_ucq_object *ucq =
                        container_of(uobj, struct ib_ucq_object, uobject);

                idr_remove_uobj(&ib_uverbs_cq_idr, uobj);
                ib_destroy_cq(cq);
                ib_uverbs_release_ucq(file, ev_file, ucq);
                kfree(ucq);
        }

        list_for_each_entry_safe(uobj, tmp, &context->mr_list, list) {
                struct ib_mr *mr = uobj->object;

                idr_remove_uobj(&ib_uverbs_mr_idr, uobj);
                ib_dereg_mr(mr);
                kfree(uobj);
        }

        mutex_lock(&file->device->xrcd_tree_mutex);
        list_for_each_entry_safe(uobj, tmp, &context->xrcd_list, list) {
                struct ib_xrcd *xrcd = uobj->object;
                struct ib_uxrcd_object *uxrcd =
                        container_of(uobj, struct ib_uxrcd_object, uobject);

                idr_remove_uobj(&ib_uverbs_xrcd_idr, uobj);
                ib_uverbs_dealloc_xrcd(file->device, xrcd);
                kfree(uxrcd);
        }
        mutex_unlock(&file->device->xrcd_tree_mutex);

        list_for_each_entry_safe(uobj, tmp, &context->pd_list, list) {
                struct ib_pd *pd = uobj->object;

                idr_remove_uobj(&ib_uverbs_pd_idr, uobj);
                ib_dealloc_pd(pd);
                kfree(uobj);
        }

        put_pid(context->tgid);

        return context->device->dealloc_ucontext(context);
}

static void ib_uverbs_release_file(struct kref *ref)
{
        struct ib_uverbs_file *file =
                container_of(ref, struct ib_uverbs_file, ref);

        module_put(file->device->ib_dev->owner);
        kref_put(&file->device->ref, ib_uverbs_release_dev);

        kfree(file);
}

static ssize_t ib_uverbs_event_read(struct file *filp, char __user *buf,
                                    size_t count, loff_t *pos)
{
        struct ib_uverbs_event_file *file = filp->private_data;
        struct ib_uverbs_event *event;
        int eventsz;
        int ret = 0;

        spin_lock_irq(&file->lock);

        while (list_empty(&file->event_list)) {
                spin_unlock_irq(&file->lock);

                if (filp->f_flags & O_NONBLOCK)
                        return -EAGAIN;

                if (wait_event_interruptible(file->poll_wait,
                                             !list_empty(&file->event_list)))
                        return -ERESTARTSYS;

                spin_lock_irq(&file->lock);
        }

        event = list_entry(file->event_list.next, struct ib_uverbs_event, list);

        if (file->is_async)
                eventsz = sizeof (struct ib_uverbs_async_event_desc);
        else
                eventsz = sizeof (struct ib_uverbs_comp_event_desc);

        if (eventsz > count) {
                ret   = -EINVAL;
                event = NULL;
        } else {
                list_del(file->event_list.next);
                if (event->counter) {
                        ++(*event->counter);
                        list_del(&event->obj_list);
                }
        }

        spin_unlock_irq(&file->lock);

        if (event) {
                if (copy_to_user(buf, event, eventsz))
                        ret = -EFAULT;
                else
                        ret = eventsz;
        }

        kfree(event);

        return ret;
}

static unsigned int ib_uverbs_event_poll(struct file *filp,
                                         struct poll_table_struct *wait)
{
        unsigned int pollflags = 0;
        struct ib_uverbs_event_file *file = filp->private_data;

        poll_wait(filp, &file->poll_wait, wait);

        spin_lock_irq(&file->lock);
        if (!list_empty(&file->event_list))
                pollflags = POLLIN | POLLRDNORM;
        spin_unlock_irq(&file->lock);

        return pollflags;
}

static int ib_uverbs_event_fasync(int fd, struct file *filp, int on)
{
        struct ib_uverbs_event_file *file = filp->private_data;

        return fasync_helper(fd, filp, on, &file->async_queue);
}

static int ib_uverbs_event_close(struct inode *inode, struct file *filp)
{
        struct ib_uverbs_event_file *file = filp->private_data;
        struct ib_uverbs_event *entry, *tmp;

        spin_lock_irq(&file->lock);
        file->is_closed = 1;
        list_for_each_entry_safe(entry, tmp, &file->event_list, list) {
                if (entry->counter)
                        list_del(&entry->obj_list);
                kfree(entry);
        }
        spin_unlock_irq(&file->lock);

        if (file->is_async) {
                ib_unregister_event_handler(&file->uverbs_file->event_handler);
                kref_put(&file->uverbs_file->ref, ib_uverbs_release_file);
        }
        kref_put(&file->ref, ib_uverbs_release_event_file);

        return 0;
}

static const struct file_operations uverbs_event_fops = {
        .owner   = THIS_MODULE,
        .read    = ib_uverbs_event_read,
        .poll    = ib_uverbs_event_poll,
        .release = ib_uverbs_event_close,
        .fasync  = ib_uverbs_event_fasync,
        .llseek  = no_llseek,
};

void ib_uverbs_comp_handler(struct ib_cq *cq, void *cq_context)
{
        struct ib_uverbs_event_file    *file = cq_context;
        struct ib_ucq_object           *uobj;
        struct ib_uverbs_event         *entry;
        unsigned long                   flags;

        if (!file)
                return;

        spin_lock_irqsave(&file->lock, flags);
        if (file->is_closed) {
                spin_unlock_irqrestore(&file->lock, flags);
                return;
        }

        entry = kmalloc(sizeof *entry, GFP_ATOMIC);
        if (!entry) {
                spin_unlock_irqrestore(&file->lock, flags);
                return;
        }

        uobj = container_of(cq->uobject, struct ib_ucq_object, uobject);

        entry->desc.comp.cq_handle = cq->uobject->user_handle;
        entry->counter             = &uobj->comp_events_reported;

        list_add_tail(&entry->list, &file->event_list);
        list_add_tail(&entry->obj_list, &uobj->comp_list);
        spin_unlock_irqrestore(&file->lock, flags);

        wake_up_interruptible(&file->poll_wait);
        kill_fasync(&file->async_queue, SIGIO, POLL_IN);
}

static void ib_uverbs_async_handler(struct ib_uverbs_file *file,
                                    __u64 element, __u64 event,
                                    struct list_head *obj_list,
                                    u32 *counter)
{
        struct ib_uverbs_event *entry;
        unsigned long flags;

        spin_lock_irqsave(&file->async_file->lock, flags);
        if (file->async_file->is_closed) {
                spin_unlock_irqrestore(&file->async_file->lock, flags);
                return;
        }

        entry = kmalloc(sizeof *entry, GFP_ATOMIC);
        if (!entry) {
                spin_unlock_irqrestore(&file->async_file->lock, flags);
                return;
        }

        entry->desc.async.element    = element;
        entry->desc.async.event_type = event;
        entry->desc.async.reserved   = 0;
        entry->counter               = counter;

        list_add_tail(&entry->list, &file->async_file->event_list);
        if (obj_list)
                list_add_tail(&entry->obj_list, obj_list);
        spin_unlock_irqrestore(&file->async_file->lock, flags);

        wake_up_interruptible(&file->async_file->poll_wait);
        kill_fasync(&file->async_file->async_queue, SIGIO, POLL_IN);
}

void ib_uverbs_cq_event_handler(struct ib_event *event, void *context_ptr)
{
        struct ib_ucq_object *uobj = container_of(event->element.cq->uobject,
                                                  struct ib_ucq_object, uobject);

        ib_uverbs_async_handler(uobj->uverbs_file, uobj->uobject.user_handle,
                                event->event, &uobj->async_list,
                                &uobj->async_events_reported);
}

void ib_uverbs_qp_event_handler(struct ib_event *event, void *context_ptr)
{
        struct ib_uevent_object *uobj;

        /* for XRC target qp's, check that qp is live */
        if (!event->element.qp->uobject || !event->element.qp->uobject->live)
                return;

        uobj = container_of(event->element.qp->uobject,
                            struct ib_uevent_object, uobject);

        ib_uverbs_async_handler(context_ptr, uobj->uobject.user_handle,
                                event->event, &uobj->event_list,
                                &uobj->events_reported);
}

void ib_uverbs_srq_event_handler(struct ib_event *event, void *context_ptr)
{
        struct ib_uevent_object *uobj;

        uobj = container_of(event->element.srq->uobject,
                            struct ib_uevent_object, uobject);

        ib_uverbs_async_handler(context_ptr, uobj->uobject.user_handle,
                                event->event, &uobj->event_list,
                                &uobj->events_reported);
}

void ib_uverbs_event_handler(struct ib_event_handler *handler,
                             struct ib_event *event)
{
        struct ib_uverbs_file *file =
                container_of(handler, struct ib_uverbs_file, event_handler);

        ib_uverbs_async_handler(file, event->element.port_num, event->event,
                                NULL, NULL);
}

struct file *ib_uverbs_alloc_event_file(struct ib_uverbs_file *uverbs_file,
                                        int is_async)
{
        struct ib_uverbs_event_file *ev_file;
        struct file *filp;

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

        kref_init(&ev_file->ref);
        spin_lock_init(&ev_file->lock);
        INIT_LIST_HEAD(&ev_file->event_list);
        init_waitqueue_head(&ev_file->poll_wait);
        ev_file->uverbs_file = uverbs_file;
        ev_file->async_queue = NULL;
        ev_file->is_async    = is_async;
        ev_file->is_closed   = 0;

        filp = anon_inode_getfile("[infinibandevent]", &uverbs_event_fops,
                                  ev_file, O_RDONLY);
        if (IS_ERR(filp))
                kfree(ev_file);

        return filp;
}

/*
 * Look up a completion event file by FD.  If lookup is successful,
 * takes a ref to the event file struct that it returns; if
 * unsuccessful, returns NULL.
 */
struct ib_uverbs_event_file *ib_uverbs_lookup_comp_file(int fd)
{
        struct ib_uverbs_event_file *ev_file = NULL;
        struct fd f = fdget(fd);

        if (!f.file)
                return NULL;

        if (f.file->f_op != &uverbs_event_fops)
                goto out;

        ev_file = f.file->private_data;
        if (ev_file->is_async) {
                ev_file = NULL;
                goto out;
        }

        kref_get(&ev_file->ref);

out:
        fdput(f);
        return ev_file;
}

static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf,
                             size_t count, loff_t *pos)
{
        struct ib_uverbs_file *file = filp->private_data;
        struct ib_uverbs_cmd_hdr hdr;
        __u32 flags;

        if (count < sizeof hdr)
                return -EINVAL;

        if (copy_from_user(&hdr, buf, sizeof hdr))
                return -EFAULT;

        flags = (hdr.command &
                 IB_USER_VERBS_CMD_FLAGS_MASK) >> IB_USER_VERBS_CMD_FLAGS_SHIFT;

        if (!flags) {
                __u32 command;

                if (hdr.command & ~(__u32)(IB_USER_VERBS_CMD_FLAGS_MASK |
                                           IB_USER_VERBS_CMD_COMMAND_MASK))
                        return -EINVAL;

                command = hdr.command & IB_USER_VERBS_CMD_COMMAND_MASK;

                if (command >= ARRAY_SIZE(uverbs_cmd_table) ||
                    !uverbs_cmd_table[command])
                        return -EINVAL;

                if (!file->ucontext &&
                    command != IB_USER_VERBS_CMD_GET_CONTEXT)
                        return -EINVAL;

                if (!(file->device->ib_dev->uverbs_cmd_mask & (1ull << command)))
                        return -ENOSYS;

                if (hdr.in_words * 4 != count)
                        return -EINVAL;

                return uverbs_cmd_table[command](file,
                                                 buf + sizeof(hdr),
                                                 hdr.in_words * 4,
                                                 hdr.out_words * 4);

        } else if (flags == IB_USER_VERBS_CMD_FLAG_EXTENDED) {
                __u32 command;

                struct ib_uverbs_ex_cmd_hdr ex_hdr;
                struct ib_udata ucore;
                struct ib_udata uhw;
                int err;
                size_t written_count = count;

                if (hdr.command & ~(__u32)(IB_USER_VERBS_CMD_FLAGS_MASK |
                                           IB_USER_VERBS_CMD_COMMAND_MASK))
                        return -EINVAL;

                command = hdr.command & IB_USER_VERBS_CMD_COMMAND_MASK;

                if (command >= ARRAY_SIZE(uverbs_ex_cmd_table) ||
                    !uverbs_ex_cmd_table[command])
                        return -ENOSYS;

                if (!file->ucontext)
                        return -EINVAL;

                if (!(file->device->ib_dev->uverbs_ex_cmd_mask & (1ull << command)))
                        return -ENOSYS;

                if (count < (sizeof(hdr) + sizeof(ex_hdr)))
                        return -EINVAL;

                if (copy_from_user(&ex_hdr, buf + sizeof(hdr), sizeof(ex_hdr)))
                        return -EFAULT;

                count -= sizeof(hdr) + sizeof(ex_hdr);
                buf += sizeof(hdr) + sizeof(ex_hdr);

                if ((hdr.in_words + ex_hdr.provider_in_words) * 8 != count)
                        return -EINVAL;

                if (ex_hdr.cmd_hdr_reserved)
                        return -EINVAL;

                if (ex_hdr.response) {
                        if (!hdr.out_words && !ex_hdr.provider_out_words)
                                return -EINVAL;

                        if (!access_ok(VERIFY_WRITE,
                                       (void __user *) (unsigned long) ex_hdr.response,
                                       (hdr.out_words + ex_hdr.provider_out_words) * 8))
                                return -EFAULT;
                } else {
                        if (hdr.out_words || ex_hdr.provider_out_words)
                                return -EINVAL;
                }

                INIT_UDATA_BUF_OR_NULL(&ucore, buf, (unsigned long) ex_hdr.response,
                                       hdr.in_words * 8, hdr.out_words * 8);

                INIT_UDATA_BUF_OR_NULL(&uhw,
                                       buf + ucore.inlen,
                                       (unsigned long) ex_hdr.response + ucore.outlen,
                                       ex_hdr.provider_in_words * 8,
                                       ex_hdr.provider_out_words * 8);

                err = uverbs_ex_cmd_table[command](file,
                                                   &ucore,
                                                   &uhw);

                if (err)
                        return err;

                return written_count;
        }

        return -ENOSYS;
}

static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
{
        struct ib_uverbs_file *file = filp->private_data;

        if (!file->ucontext)
                return -ENODEV;
        else
                return file->device->ib_dev->mmap(file->ucontext, vma);
}

/*
 * ib_uverbs_open() does not need the BKL:
 *
 *  - the ib_uverbs_device structures are properly reference counted and
 *    everything else is purely local to the file being created, so
 *    races against other open calls are not a problem;
 *  - there is no ioctl method to race against;
 *  - the open method will either immediately run -ENXIO, or all
 *    required initialization will be done.
 */
static int ib_uverbs_open(struct inode *inode, struct file *filp)
{
        struct ib_uverbs_device *dev;
        struct ib_uverbs_file *file;
        int ret;

        dev = container_of(inode->i_cdev, struct ib_uverbs_device, cdev);
        if (dev)
                kref_get(&dev->ref);
        else
                return -ENXIO;

        if (!try_module_get(dev->ib_dev->owner)) {
                ret = -ENODEV;
                goto err;
        }

        file = kmalloc(sizeof *file, GFP_KERNEL);
        if (!file) {
                ret = -ENOMEM;
                goto err_module;
        }

        file->device     = dev;
        file->ucontext   = NULL;
        file->async_file = NULL;
        kref_init(&file->ref);
        mutex_init(&file->mutex);

        filp->private_data = file;

        return nonseekable_open(inode, filp);

err_module:
        module_put(dev->ib_dev->owner);

err:
        kref_put(&dev->ref, ib_uverbs_release_dev);
        return ret;
}

static int ib_uverbs_close(struct inode *inode, struct file *filp)
{
        struct ib_uverbs_file *file = filp->private_data;

        ib_uverbs_cleanup_ucontext(file, file->ucontext);

        if (file->async_file)
                kref_put(&file->async_file->ref, ib_uverbs_release_event_file);

        kref_put(&file->ref, ib_uverbs_release_file);

        return 0;
}

static const struct file_operations uverbs_fops = {
        .owner   = THIS_MODULE,
        .write   = ib_uverbs_write,
        .open    = ib_uverbs_open,
        .release = ib_uverbs_close,
        .llseek  = no_llseek,
};

static const struct file_operations uverbs_mmap_fops = {
        .owner   = THIS_MODULE,
        .write   = ib_uverbs_write,
        .mmap    = ib_uverbs_mmap,
        .open    = ib_uverbs_open,
        .release = ib_uverbs_close,
        .llseek  = no_llseek,
};

static struct ib_client uverbs_client = {
        .name   = "uverbs",
        .add    = ib_uverbs_add_one,
        .remove = ib_uverbs_remove_one
};

static ssize_t show_ibdev(struct device *device, struct device_attribute *attr,
                          char *buf)
{
        struct ib_uverbs_device *dev = dev_get_drvdata(device);

        if (!dev)
                return -ENODEV;

        return sprintf(buf, "%s\n", dev->ib_dev->name);
}
static DEVICE_ATTR(ibdev, S_IRUGO, show_ibdev, NULL);

static ssize_t show_dev_abi_version(struct device *device,
                                    struct device_attribute *attr, char *buf)
{
        struct ib_uverbs_device *dev = dev_get_drvdata(device);

        if (!dev)
                return -ENODEV;

        return sprintf(buf, "%d\n", dev->ib_dev->uverbs_abi_ver);
}
static DEVICE_ATTR(abi_version, S_IRUGO, show_dev_abi_version, NULL);

static CLASS_ATTR_STRING(abi_version, S_IRUGO,
                         __stringify(IB_USER_VERBS_ABI_VERSION));

static dev_t overflow_maj;
static DECLARE_BITMAP(overflow_map, IB_UVERBS_MAX_DEVICES);

/*
 * If we have more than IB_UVERBS_MAX_DEVICES, dynamically overflow by
 * requesting a new major number and doubling the number of max devices we
 * support. It's stupid, but simple.
 */
static int find_overflow_devnum(void)
{
        int ret;

        if (!overflow_maj) {
                ret = alloc_chrdev_region(&overflow_maj, 0, IB_UVERBS_MAX_DEVICES,
                                          "infiniband_verbs");
                if (ret) {
                        printk(KERN_ERR "user_verbs: couldn't register dynamic device number\n");
                        return ret;
                }
        }

        ret = find_first_zero_bit(overflow_map, IB_UVERBS_MAX_DEVICES);
        if (ret >= IB_UVERBS_MAX_DEVICES)
                return -1;

        return ret;
}

static void ib_uverbs_add_one(struct ib_device *device)
{
        int devnum;
        dev_t base;
        struct ib_uverbs_device *uverbs_dev;

        if (!device->alloc_ucontext)
                return;

        uverbs_dev = kzalloc(sizeof *uverbs_dev, GFP_KERNEL);
        if (!uverbs_dev)
                return;

        kref_init(&uverbs_dev->ref);
        init_completion(&uverbs_dev->comp);
        uverbs_dev->xrcd_tree = RB_ROOT;
        mutex_init(&uverbs_dev->xrcd_tree_mutex);

        spin_lock(&map_lock);
        devnum = find_first_zero_bit(dev_map, IB_UVERBS_MAX_DEVICES);
        if (devnum >= IB_UVERBS_MAX_DEVICES) {
                spin_unlock(&map_lock);
                devnum = find_overflow_devnum();
                if (devnum < 0)
                        goto err;

                spin_lock(&map_lock);
                uverbs_dev->devnum = devnum + IB_UVERBS_MAX_DEVICES;
                base = devnum + overflow_maj;
                set_bit(devnum, overflow_map);
        } else {
                uverbs_dev->devnum = devnum;
                base = devnum + IB_UVERBS_BASE_DEV;
                set_bit(devnum, dev_map);
        }
        spin_unlock(&map_lock);

        uverbs_dev->ib_dev           = device;
        uverbs_dev->num_comp_vectors = device->num_comp_vectors;

        cdev_init(&uverbs_dev->cdev, NULL);
        uverbs_dev->cdev.owner = THIS_MODULE;
        uverbs_dev->cdev.ops = device->mmap ? &uverbs_mmap_fops : &uverbs_fops;
        kobject_set_name(&uverbs_dev->cdev.kobj, "uverbs%d", uverbs_dev->devnum);
        if (cdev_add(&uverbs_dev->cdev, base, 1))
                goto err_cdev;

        uverbs_dev->dev = device_create(uverbs_class, device->dma_device,
                                        uverbs_dev->cdev.dev, uverbs_dev,
                                        "uverbs%d", uverbs_dev->devnum);
        if (IS_ERR(uverbs_dev->dev))
                goto err_cdev;

        if (device_create_file(uverbs_dev->dev, &dev_attr_ibdev))
                goto err_class;
        if (device_create_file(uverbs_dev->dev, &dev_attr_abi_version))
                goto err_class;

        ib_set_client_data(device, &uverbs_client, uverbs_dev);

        return;

err_class:
        device_destroy(uverbs_class, uverbs_dev->cdev.dev);

err_cdev:
        cdev_del(&uverbs_dev->cdev);
        if (uverbs_dev->devnum < IB_UVERBS_MAX_DEVICES)
                clear_bit(devnum, dev_map);
        else
                clear_bit(devnum, overflow_map);

err:
        kref_put(&uverbs_dev->ref, ib_uverbs_release_dev);
        wait_for_completion(&uverbs_dev->comp);
        kfree(uverbs_dev);
        return;
}

static void ib_uverbs_remove_one(struct ib_device *device)
{
        struct ib_uverbs_device *uverbs_dev = ib_get_client_data(device, &uverbs_client);

        if (!uverbs_dev)
                return;

        dev_set_drvdata(uverbs_dev->dev, NULL);
        device_destroy(uverbs_class, uverbs_dev->cdev.dev);
        cdev_del(&uverbs_dev->cdev);

        if (uverbs_dev->devnum < IB_UVERBS_MAX_DEVICES)
                clear_bit(uverbs_dev->devnum, dev_map);
        else
                clear_bit(uverbs_dev->devnum - IB_UVERBS_MAX_DEVICES, overflow_map);

        kref_put(&uverbs_dev->ref, ib_uverbs_release_dev);
        wait_for_completion(&uverbs_dev->comp);
        kfree(uverbs_dev);
}

static char *uverbs_devnode(struct device *dev, umode_t *mode)
{
        if (mode)
                *mode = 0666;
        return kasprintf(GFP_KERNEL, "infiniband/%s", dev_name(dev));
}

static int __init ib_uverbs_init(void)
{
        int ret;

        ret = register_chrdev_region(IB_UVERBS_BASE_DEV, IB_UVERBS_MAX_DEVICES,
                                     "infiniband_verbs");
        if (ret) {
                printk(KERN_ERR "user_verbs: couldn't register device number\n");
                goto out;
        }

        uverbs_class = class_create(THIS_MODULE, "infiniband_verbs");
        if (IS_ERR(uverbs_class)) {
                ret = PTR_ERR(uverbs_class);
                printk(KERN_ERR "user_verbs: couldn't create class infiniband_verbs\n");
                goto out_chrdev;
        }

        uverbs_class->devnode = uverbs_devnode;

        ret = class_create_file(uverbs_class, &class_attr_abi_version.attr);
        if (ret) {
                printk(KERN_ERR "user_verbs: couldn't create abi_version attribute\n");
                goto out_class;
        }

        ret = ib_register_client(&uverbs_client);
        if (ret) {
                printk(KERN_ERR "user_verbs: couldn't register client\n");
                goto out_class;
        }

        return 0;

out_class:
        class_destroy(uverbs_class);

out_chrdev:
        unregister_chrdev_region(IB_UVERBS_BASE_DEV, IB_UVERBS_MAX_DEVICES);

out:
        return ret;
}

static void __exit ib_uverbs_cleanup(void)
{
        ib_unregister_client(&uverbs_client);
        class_destroy(uverbs_class);
        unregister_chrdev_region(IB_UVERBS_BASE_DEV, IB_UVERBS_MAX_DEVICES);
        if (overflow_maj)
                unregister_chrdev_region(overflow_maj, IB_UVERBS_MAX_DEVICES);
        idr_destroy(&ib_uverbs_pd_idr);
        idr_destroy(&ib_uverbs_mr_idr);
        idr_destroy(&ib_uverbs_mw_idr);
        idr_destroy(&ib_uverbs_ah_idr);
        idr_destroy(&ib_uverbs_cq_idr);
        idr_destroy(&ib_uverbs_qp_idr);
        idr_destroy(&ib_uverbs_srq_idr);
}

module_init(ib_uverbs_init);
module_exit(ib_uverbs_cleanup);