/*
 * 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 <linux/uaccess.h>

#include <rdma/ib.h>
#include <rdma/uverbs_std_types.h>

#include "uverbs.h"
#include "core_priv.h"
#include "rdma_core.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;

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,
                                     struct ib_device *ib_dev,
                                     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_device *ib_dev,
                                    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,
        [IB_USER_VERBS_EX_CMD_CREATE_QP]        = ib_uverbs_ex_create_qp,
        [IB_USER_VERBS_EX_CMD_CREATE_WQ]        = ib_uverbs_ex_create_wq,
        [IB_USER_VERBS_EX_CMD_MODIFY_WQ]        = ib_uverbs_ex_modify_wq,
        [IB_USER_VERBS_EX_CMD_DESTROY_WQ]       = ib_uverbs_ex_destroy_wq,
        [IB_USER_VERBS_EX_CMD_CREATE_RWQ_IND_TBL] = ib_uverbs_ex_create_rwq_ind_table,
        [IB_USER_VERBS_EX_CMD_DESTROY_RWQ_IND_TBL] = ib_uverbs_ex_destroy_rwq_ind_table,
        [IB_USER_VERBS_EX_CMD_MODIFY_QP]        = ib_uverbs_ex_modify_qp,
};

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

int uverbs_dealloc_mw(struct ib_mw *mw)
{
        struct ib_pd *pd = mw->pd;
        int ret;

        ret = mw->device->dealloc_mw(mw);
        if (!ret)
                atomic_dec(&pd->usecnt);
        return ret;
}

static void ib_uverbs_release_dev(struct kobject *kobj)
{
        struct ib_uverbs_device *dev =
                container_of(kobj, struct ib_uverbs_device, kobj);

        cleanup_srcu_struct(&dev->disassociate_srcu);
        kfree(dev);
}

static struct kobj_type ib_uverbs_dev_ktype = {
        .release = ib_uverbs_release_dev,
};

static void ib_uverbs_release_async_event_file(struct kref *ref)
{
        struct ib_uverbs_async_event_file *file =
                container_of(ref, struct ib_uverbs_async_event_file, ref);

        kfree(file);
}

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

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

                uverbs_uobject_put(&ev_file->uobj_file.uobj);
        }

        spin_lock_irq(&file->async_file->ev_queue.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->ev_queue.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->ev_queue.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->ev_queue.lock);
}

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,
                                      bool device_removed)
{
        context->closing = 1;
        uverbs_cleanup_ucontext(context, device_removed);
        put_pid(context->tgid);

        ib_rdmacg_uncharge(&context->cg_obj, context->device,
                           RDMACG_RESOURCE_HCA_HANDLE);

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

static void ib_uverbs_comp_dev(struct ib_uverbs_device *dev)
{
        complete(&dev->comp);
}

void ib_uverbs_release_file(struct kref *ref)
{
        struct ib_uverbs_file *file =
                container_of(ref, struct ib_uverbs_file, ref);
        struct ib_device *ib_dev;
        int srcu_key;

        srcu_key = srcu_read_lock(&file->device->disassociate_srcu);
        ib_dev = srcu_dereference(file->device->ib_dev,
                                  &file->device->disassociate_srcu);
        if (ib_dev && !ib_dev->disassociate_ucontext)
                module_put(ib_dev->owner);
        srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);

        if (atomic_dec_and_test(&file->device->refcount))
                ib_uverbs_comp_dev(file->device);

        kobject_put(&file->device->kobj);
        kfree(file);
}

static ssize_t ib_uverbs_event_read(struct ib_uverbs_event_queue *ev_queue,
                                    struct ib_uverbs_file *uverbs_file,
                                    struct file *filp, char __user *buf,
                                    size_t count, loff_t *pos,
                                    size_t eventsz)
{
        struct ib_uverbs_event *event;
        int ret = 0;

        spin_lock_irq(&ev_queue->lock);

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

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

                if (wait_event_interruptible(ev_queue->poll_wait,
                                             (!list_empty(&ev_queue->event_list) ||
                        /* The barriers built into wait_event_interruptible()
                         * and wake_up() guarentee this will see the null set
                         * without using RCU
                         */
                                             !uverbs_file->device->ib_dev)))
                        return -ERESTARTSYS;

                /* If device was disassociated and no event exists set an error */
                if (list_empty(&ev_queue->event_list) &&
                    !uverbs_file->device->ib_dev)
                        return -EIO;

                spin_lock_irq(&ev_queue->lock);
        }

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

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

        spin_unlock_irq(&ev_queue->lock);

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

        kfree(event);

        return ret;
}

static ssize_t ib_uverbs_async_event_read(struct file *filp, char __user *buf,
                                          size_t count, loff_t *pos)
{
        struct ib_uverbs_async_event_file *file = filp->private_data;

        return ib_uverbs_event_read(&file->ev_queue, file->uverbs_file, filp,
                                    buf, count, pos,
                                    sizeof(struct ib_uverbs_async_event_desc));
}

static ssize_t ib_uverbs_comp_event_read(struct file *filp, char __user *buf,
                                         size_t count, loff_t *pos)
{
        struct ib_uverbs_completion_event_file *comp_ev_file =
                filp->private_data;

        return ib_uverbs_event_read(&comp_ev_file->ev_queue,
                                    comp_ev_file->uobj_file.ufile, filp,
                                    buf, count, pos,
                                    sizeof(struct ib_uverbs_comp_event_desc));
}

static unsigned int ib_uverbs_event_poll(struct ib_uverbs_event_queue *ev_queue,
                                         struct file *filp,
                                         struct poll_table_struct *wait)
{
        unsigned int pollflags = 0;

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

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

        return pollflags;
}

static unsigned int ib_uverbs_async_event_poll(struct file *filp,
                                               struct poll_table_struct *wait)
{
        return ib_uverbs_event_poll(filp->private_data, filp, wait);
}

static unsigned int ib_uverbs_comp_event_poll(struct file *filp,
                                              struct poll_table_struct *wait)
{
        struct ib_uverbs_completion_event_file *comp_ev_file =
                filp->private_data;

        return ib_uverbs_event_poll(&comp_ev_file->ev_queue, filp, wait);
}

static int ib_uverbs_async_event_fasync(int fd, struct file *filp, int on)
{
        struct ib_uverbs_event_queue *ev_queue = filp->private_data;

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

static int ib_uverbs_comp_event_fasync(int fd, struct file *filp, int on)
{
        struct ib_uverbs_completion_event_file *comp_ev_file =
                filp->private_data;

        return fasync_helper(fd, filp, on, &comp_ev_file->ev_queue.async_queue);
}

static int ib_uverbs_async_event_close(struct inode *inode, struct file *filp)
{
        struct ib_uverbs_async_event_file *file = filp->private_data;
        struct ib_uverbs_file *uverbs_file = file->uverbs_file;
        struct ib_uverbs_event *entry, *tmp;
        int closed_already = 0;

        mutex_lock(&uverbs_file->device->lists_mutex);
        spin_lock_irq(&file->ev_queue.lock);
        closed_already = file->ev_queue.is_closed;
        file->ev_queue.is_closed = 1;
        list_for_each_entry_safe(entry, tmp, &file->ev_queue.event_list, list) {
                if (entry->counter)
                        list_del(&entry->obj_list);
                kfree(entry);
        }
        spin_unlock_irq(&file->ev_queue.lock);
        if (!closed_already) {
                list_del(&file->list);
                ib_unregister_event_handler(&uverbs_file->event_handler);
        }
        mutex_unlock(&uverbs_file->device->lists_mutex);

        kref_put(&uverbs_file->ref, ib_uverbs_release_file);
        kref_put(&file->ref, ib_uverbs_release_async_event_file);

        return 0;
}

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

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

        uverbs_close_fd(filp);

        return 0;
}

const struct file_operations uverbs_event_fops = {
        .owner   = THIS_MODULE,
        .read    = ib_uverbs_comp_event_read,
        .poll    = ib_uverbs_comp_event_poll,
        .release = ib_uverbs_comp_event_close,
        .fasync  = ib_uverbs_comp_event_fasync,
        .llseek  = no_llseek,
};

static const struct file_operations uverbs_async_event_fops = {
        .owner   = THIS_MODULE,
        .read    = ib_uverbs_async_event_read,
        .poll    = ib_uverbs_async_event_poll,
        .release = ib_uverbs_async_event_close,
        .fasync  = ib_uverbs_async_event_fasync,
        .llseek  = no_llseek,
};

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

        if (!ev_queue)
                return;

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

        entry = kmalloc(sizeof *entry, GFP_ATOMIC);
        if (!entry) {
                spin_unlock_irqrestore(&ev_queue->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, &ev_queue->event_list);
        list_add_tail(&entry->obj_list, &uobj->comp_list);
        spin_unlock_irqrestore(&ev_queue->lock, flags);

        wake_up_interruptible(&ev_queue->poll_wait);
        kill_fasync(&ev_queue->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->ev_queue.lock, flags);
        if (file->async_file->ev_queue.is_closed) {
                spin_unlock_irqrestore(&file->async_file->ev_queue.lock, flags);
                return;
        }

        entry = kmalloc(sizeof *entry, GFP_ATOMIC);
        if (!entry) {
                spin_unlock_irqrestore(&file->async_file->ev_queue.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->ev_queue.event_list);
        if (obj_list)
                list_add_tail(&entry->obj_list, obj_list);
        spin_unlock_irqrestore(&file->async_file->ev_queue.lock, flags);

        wake_up_interruptible(&file->async_file->ev_queue.poll_wait);
        kill_fasync(&file->async_file->ev_queue.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)
                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_wq_event_handler(struct ib_event *event, void *context_ptr)
{
        struct ib_uevent_object *uobj = container_of(event->element.wq->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);
}

void ib_uverbs_free_async_event_file(struct ib_uverbs_file *file)
{
        kref_put(&file->async_file->ref, ib_uverbs_release_async_event_file);
        file->async_file = NULL;
}

void ib_uverbs_init_event_queue(struct ib_uverbs_event_queue *ev_queue)
{
        spin_lock_init(&ev_queue->lock);
        INIT_LIST_HEAD(&ev_queue->event_list);
        init_waitqueue_head(&ev_queue->poll_wait);
        ev_queue->is_closed   = 0;
        ev_queue->async_queue = NULL;
}

struct file *ib_uverbs_alloc_async_event_file(struct ib_uverbs_file *uverbs_file,
                                              struct ib_device  *ib_dev)
{
        struct ib_uverbs_async_event_file *ev_file;
        struct file *filp;

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

        ib_uverbs_init_event_queue(&ev_file->ev_queue);
        ev_file->uverbs_file = uverbs_file;
        kref_get(&ev_file->uverbs_file->ref);
        kref_init(&ev_file->ref);
        filp = anon_inode_getfile("[infinibandevent]", &uverbs_async_event_fops,
                                  ev_file, O_RDONLY);
        if (IS_ERR(filp))
                goto err_put_refs;

        mutex_lock(&uverbs_file->device->lists_mutex);
        list_add_tail(&ev_file->list,
                      &uverbs_file->device->uverbs_events_file_list);
        mutex_unlock(&uverbs_file->device->lists_mutex);

        WARN_ON(uverbs_file->async_file);
        uverbs_file->async_file = ev_file;
        kref_get(&uverbs_file->async_file->ref);
        INIT_IB_EVENT_HANDLER(&uverbs_file->event_handler,
                              ib_dev,
                              ib_uverbs_event_handler);
        ib_register_event_handler(&uverbs_file->event_handler);
        /* At that point async file stuff was fully set */

        return filp;

err_put_refs:
        kref_put(&ev_file->uverbs_file->ref, ib_uverbs_release_file);
        kref_put(&ev_file->ref, ib_uverbs_release_async_event_file);
        return filp;
}

static int verify_command_mask(struct ib_device *ib_dev, __u32 command)
{
        u64 mask;

        if (command <= IB_USER_VERBS_CMD_OPEN_QP)
                mask = ib_dev->uverbs_cmd_mask;
        else
                mask = ib_dev->uverbs_ex_cmd_mask;

        if (mask & ((u64)1 << command))
                return 0;

        return -1;
}

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_device *ib_dev;
        struct ib_uverbs_cmd_hdr hdr;
        __u32 command;
        __u32 flags;
        int srcu_key;
        ssize_t ret;

        if (!ib_safe_file_access(filp)) {
                pr_err_once("uverbs_write: process %d (%s) changed security contexts after opening file descriptor, this is not allowed.\n",
                            task_tgid_vnr(current), current->comm);
                return -EACCES;
        }

        if (count < sizeof hdr)
                return -EINVAL;

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

        srcu_key = srcu_read_lock(&file->device->disassociate_srcu);
        ib_dev = srcu_dereference(file->device->ib_dev,
                                  &file->device->disassociate_srcu);
        if (!ib_dev) {
                ret = -EIO;
                goto out;
        }

        if (hdr.command & ~(__u32)(IB_USER_VERBS_CMD_FLAGS_MASK |
                                   IB_USER_VERBS_CMD_COMMAND_MASK)) {
                ret = -EINVAL;
                goto out;
        }

        command = hdr.command & IB_USER_VERBS_CMD_COMMAND_MASK;
        if (verify_command_mask(ib_dev, command)) {
                ret = -EOPNOTSUPP;
                goto out;
        }

        if (!file->ucontext &&
            command != IB_USER_VERBS_CMD_GET_CONTEXT) {
                ret = -EINVAL;
                goto out;
        }

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

        if (!flags) {
                if (command >= ARRAY_SIZE(uverbs_cmd_table) ||
                    !uverbs_cmd_table[command]) {
                        ret = -EINVAL;
                        goto out;
                }

                if (hdr.in_words * 4 != count) {
                        ret = -EINVAL;
                        goto out;
                }

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

        } else if (flags == IB_USER_VERBS_CMD_FLAG_EXTENDED) {
                struct ib_uverbs_ex_cmd_hdr ex_hdr;
                struct ib_udata ucore;
                struct ib_udata uhw;
                size_t written_count = count;

                if (command >= ARRAY_SIZE(uverbs_ex_cmd_table) ||
                    !uverbs_ex_cmd_table[command]) {
                        ret = -ENOSYS;
                        goto out;
                }

                if (!file->ucontext) {
                        ret = -EINVAL;
                        goto out;
                }

                if (count < (sizeof(hdr) + sizeof(ex_hdr))) {
                        ret = -EINVAL;
                        goto out;
                }

                if (copy_from_user(&ex_hdr, buf + sizeof(hdr), sizeof(ex_hdr))) {
                        ret = -EFAULT;
                        goto out;
                }

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

                if ((hdr.in_words + ex_hdr.provider_in_words) * 8 != count) {
                        ret = -EINVAL;
                        goto out;
                }

                if (ex_hdr.cmd_hdr_reserved) {
                        ret = -EINVAL;
                        goto out;
                }

                if (ex_hdr.response) {
                        if (!hdr.out_words && !ex_hdr.provider_out_words) {
                                ret = -EINVAL;
                                goto out;
                        }

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

                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);

                ret = uverbs_ex_cmd_table[command](file,
                                                   ib_dev,
                                                   &ucore,
                                                   &uhw);
                if (!ret)
                        ret = written_count;
        } else {
                ret = -ENOSYS;
        }

out:
        srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
        return ret;
}

static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
{
        struct ib_uverbs_file *file = filp->private_data;
        struct ib_device *ib_dev;
        int ret = 0;
        int srcu_key;

        srcu_key = srcu_read_lock(&file->device->disassociate_srcu);
        ib_dev = srcu_dereference(file->device->ib_dev,
                                  &file->device->disassociate_srcu);
        if (!ib_dev) {
                ret = -EIO;
                goto out;
        }

        if (!file->ucontext)
                ret = -ENODEV;
        else
                ret = ib_dev->mmap(file->ucontext, vma);
out:
        srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
        return ret;
}

/*
 * 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;
        struct ib_device *ib_dev;
        int ret;
        int module_dependent;
        int srcu_key;

        dev = container_of(inode->i_cdev, struct ib_uverbs_device, cdev);
        if (!atomic_inc_not_zero(&dev->refcount))
                return -ENXIO;

        srcu_key = srcu_read_lock(&dev->disassociate_srcu);
        mutex_lock(&dev->lists_mutex);
        ib_dev = srcu_dereference(dev->ib_dev,
                                  &dev->disassociate_srcu);
        if (!ib_dev) {
                ret = -EIO;
                goto err;
        }

        /* In case IB device supports disassociate ucontext, there is no hard
         * dependency between uverbs device and its low level device.
         */
        module_dependent = !(ib_dev->disassociate_ucontext);

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

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

                goto err;
        }

        file->device     = dev;
        spin_lock_init(&file->idr_lock);
        idr_init(&file->idr);
        file->ucontext   = NULL;
        file->async_file = NULL;
        kref_init(&file->ref);
        mutex_init(&file->mutex);
        mutex_init(&file->cleanup_mutex);

        filp->private_data = file;
        kobject_get(&dev->kobj);
        list_add_tail(&file->list, &dev->uverbs_file_list);
        mutex_unlock(&dev->lists_mutex);
        srcu_read_unlock(&dev->disassociate_srcu, srcu_key);

        return nonseekable_open(inode, filp);

err_module:
        module_put(ib_dev->owner);

err:
        mutex_unlock(&dev->lists_mutex);
        srcu_read_unlock(&dev->disassociate_srcu, srcu_key);
        if (atomic_dec_and_test(&dev->refcount))
                ib_uverbs_comp_dev(dev);

        return ret;
}

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

        mutex_lock(&file->cleanup_mutex);
        if (file->ucontext) {
                ib_uverbs_cleanup_ucontext(file, file->ucontext, false);
                file->ucontext = NULL;
        }
        mutex_unlock(&file->cleanup_mutex);
        idr_destroy(&file->idr);

        mutex_lock(&file->device->lists_mutex);
        if (!file->is_closed) {
                list_del(&file->list);
                file->is_closed = 1;
        }
        mutex_unlock(&file->device->lists_mutex);

        if (file->async_file)
                kref_put(&file->async_file->ref,
                         ib_uverbs_release_async_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,
#if IS_ENABLED(CONFIG_INFINIBAND_EXP_USER_ACCESS)
        .unlocked_ioctl = ib_uverbs_ioctl,
#endif
};

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,
#if IS_ENABLED(CONFIG_INFINIBAND_EXP_USER_ACCESS)
        .unlocked_ioctl = ib_uverbs_ioctl,
#endif
};

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)
{
        int ret = -ENODEV;
        int srcu_key;
        struct ib_uverbs_device *dev = dev_get_drvdata(device);
        struct ib_device *ib_dev;

        if (!dev)
                return -ENODEV;

        srcu_key = srcu_read_lock(&dev->disassociate_srcu);
        ib_dev = srcu_dereference(dev->ib_dev, &dev->disassociate_srcu);
        if (ib_dev)
                ret = sprintf(buf, "%s\n", ib_dev->name);
        srcu_read_unlock(&dev->disassociate_srcu, srcu_key);

        return ret;
}
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);
        int ret = -ENODEV;
        int srcu_key;
        struct ib_device *ib_dev;

        if (!dev)
                return -ENODEV;
        srcu_key = srcu_read_lock(&dev->disassociate_srcu);
        ib_dev = srcu_dereference(dev->ib_dev, &dev->disassociate_srcu);
        if (ib_dev)
                ret = sprintf(buf, "%d\n", ib_dev->uverbs_abi_ver);
        srcu_read_unlock(&dev->disassociate_srcu, srcu_key);

        return ret;
}
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) {
                        pr_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;
        int ret;

        if (!device->alloc_ucontext)
                return;

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

        ret = init_srcu_struct(&uverbs_dev->disassociate_srcu);
        if (ret) {
                kfree(uverbs_dev);
                return;
        }

        atomic_set(&uverbs_dev->refcount, 1);
        init_completion(&uverbs_dev->comp);
        uverbs_dev->xrcd_tree = RB_ROOT;
        mutex_init(&uverbs_dev->xrcd_tree_mutex);
        kobject_init(&uverbs_dev->kobj, &ib_uverbs_dev_ktype);
        mutex_init(&uverbs_dev->lists_mutex);
        INIT_LIST_HEAD(&uverbs_dev->uverbs_file_list);
        INIT_LIST_HEAD(&uverbs_dev->uverbs_events_file_list);

        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);

        rcu_assign_pointer(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;
        cdev_set_parent(&uverbs_dev->cdev, &uverbs_dev->kobj);
        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->dev.parent,
                                        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;

        if (!device->specs_root) {
                const struct uverbs_object_tree_def *default_root[] = {
                        uverbs_default_get_objects()};

                uverbs_dev->specs_root = uverbs_alloc_spec_tree(1,
                                                                default_root);
                if (IS_ERR(uverbs_dev->specs_root))
                        goto err_class;

                device->specs_root = uverbs_dev->specs_root;
        }

        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:
        if (atomic_dec_and_test(&uverbs_dev->refcount))
                ib_uverbs_comp_dev(uverbs_dev);
        wait_for_completion(&uverbs_dev->comp);
        kobject_put(&uverbs_dev->kobj);
        return;
}

static void ib_uverbs_free_hw_resources(struct ib_uverbs_device *uverbs_dev,
                                        struct ib_device *ib_dev)
{
        struct ib_uverbs_file *file;
        struct ib_uverbs_async_event_file *event_file;
        struct ib_event event;

        /* Pending running commands to terminate */
        synchronize_srcu(&uverbs_dev->disassociate_srcu);
        event.event = IB_EVENT_DEVICE_FATAL;
        event.element.port_num = 0;
        event.device = ib_dev;

        mutex_lock(&uverbs_dev->lists_mutex);
        while (!list_empty(&uverbs_dev->uverbs_file_list)) {
                struct ib_ucontext *ucontext;
                file = list_first_entry(&uverbs_dev->uverbs_file_list,
                                        struct ib_uverbs_file, list);
                file->is_closed = 1;
                list_del(&file->list);
                kref_get(&file->ref);
                mutex_unlock(&uverbs_dev->lists_mutex);


                mutex_lock(&file->cleanup_mutex);
                ucontext = file->ucontext;
                file->ucontext = NULL;
                mutex_unlock(&file->cleanup_mutex);

                /* At this point ib_uverbs_close cannot be running
                 * ib_uverbs_cleanup_ucontext
                 */
                if (ucontext) {
                        /* We must release the mutex before going ahead and
                         * calling disassociate_ucontext. disassociate_ucontext
                         * might end up indirectly calling uverbs_close,
                         * for example due to freeing the resources
                         * (e.g mmput).
                         */
                        ib_uverbs_event_handler(&file->event_handler, &event);
                        ib_dev->disassociate_ucontext(ucontext);
                        mutex_lock(&file->cleanup_mutex);
                        ib_uverbs_cleanup_ucontext(file, ucontext, true);
                        mutex_unlock(&file->cleanup_mutex);
                }

                mutex_lock(&uverbs_dev->lists_mutex);
                kref_put(&file->ref, ib_uverbs_release_file);
        }

        while (!list_empty(&uverbs_dev->uverbs_events_file_list)) {
                event_file = list_first_entry(&uverbs_dev->
                                              uverbs_events_file_list,
                                              struct ib_uverbs_async_event_file,
                                              list);
                spin_lock_irq(&event_file->ev_queue.lock);
                event_file->ev_queue.is_closed = 1;
                spin_unlock_irq(&event_file->ev_queue.lock);

                list_del(&event_file->list);
                ib_unregister_event_handler(
                        &event_file->uverbs_file->event_handler);
                event_file->uverbs_file->event_handler.device =
                        NULL;

                wake_up_interruptible(&event_file->ev_queue.poll_wait);
                kill_fasync(&event_file->ev_queue.async_queue, SIGIO, POLL_IN);
        }
        mutex_unlock(&uverbs_dev->lists_mutex);
}

static void ib_uverbs_remove_one(struct ib_device *device, void *client_data)
{
        struct ib_uverbs_device *uverbs_dev = client_data;
        int wait_clients = 1;

        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);

        if (device->disassociate_ucontext) {
                /* We disassociate HW resources and immediately return.
                 * Userspace will see a EIO errno for all future access.
                 * Upon returning, ib_device may be freed internally and is not
                 * valid any more.
                 * uverbs_device is still available until all clients close
                 * their files, then the uverbs device ref count will be zero
                 * and its resources will be freed.
                 * Note: At this point no more files can be opened since the
                 * cdev was deleted, however active clients can still issue
                 * commands and close their open files.
                 */
                rcu_assign_pointer(uverbs_dev->ib_dev, NULL);
                ib_uverbs_free_hw_resources(uverbs_dev, device);
                wait_clients = 0;
        }

        if (atomic_dec_and_test(&uverbs_dev->refcount))
                ib_uverbs_comp_dev(uverbs_dev);
        if (wait_clients)
                wait_for_completion(&uverbs_dev->comp);
        if (uverbs_dev->specs_root) {
                uverbs_free_spec_tree(uverbs_dev->specs_root);
                device->specs_root = NULL;
        }

        kobject_put(&uverbs_dev->kobj);
}

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) {
                pr_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);
                pr_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) {
                pr_err("user_verbs: couldn't create abi_version attribute\n");
                goto out_class;
        }

        ret = ib_register_client(&uverbs_client);
        if (ret) {
                pr_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);
}

module_init(ib_uverbs_init);
module_exit(ib_uverbs_cleanup);