/*
 * 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/sched/mm.h>

#include <linux/uaccess.h>

#include <rdma/ib.h>
#include <rdma/uverbs_std_types.h>
#include <rdma/rdma_netlink.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 = RDMA_MAX_PORTS,
        IB_UVERBS_NUM_FIXED_MINOR = 32,
        IB_UVERBS_NUM_DYNAMIC_MINOR = IB_UVERBS_MAX_DEVICES - IB_UVERBS_NUM_FIXED_MINOR,
};

#define IB_UVERBS_BASE_DEV      MKDEV(IB_UVERBS_MAJOR, IB_UVERBS_BASE_MINOR)

static dev_t dynamic_uverbs_dev;
static struct class *uverbs_class;

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

/*
 * Must be called with the ufile->device->disassociate_srcu held, and the lock
 * must be held until use of the ucontext is finished.
 */
struct ib_ucontext *ib_uverbs_get_ucontext_file(struct ib_uverbs_file *ufile)
{
        /*
         * We do not hold the hw_destroy_rwsem lock for this flow, instead
         * srcu is used. It does not matter if someone races this with
         * get_context, we get NULL or valid ucontext.
         */
        struct ib_ucontext *ucontext = smp_load_acquire(&ufile->ucontext);

        if (!srcu_dereference(ufile->device->ib_dev,
                              &ufile->device->disassociate_srcu))
                return ERR_PTR(-EIO);

        if (!ucontext)
                return ERR_PTR(-EINVAL);

        return ucontext;
}
EXPORT_SYMBOL(ib_uverbs_get_ucontext_file);

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

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

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

        uverbs_destroy_api(dev->uapi);
        cleanup_srcu_struct(&dev->disassociate_srcu);
        mutex_destroy(&dev->lists_mutex);
        mutex_destroy(&dev->xrcd_tree_mutex);
        kfree(dev);
}

void ib_uverbs_release_ucq(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);
        }

        ib_uverbs_release_uevent(&uobj->uevent);
}

void ib_uverbs_release_uevent(struct ib_uevent_object *uobj)
{
        struct ib_uverbs_async_event_file *async_file = uobj->event_file;
        struct ib_uverbs_event *evt, *tmp;

        if (!async_file)
                return;

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

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 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;

        release_ufile_idr_uobject(file);

        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->ops.disassociate_ucontext)
                module_put(ib_dev->ops.owner);
        srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);

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

        if (file->default_async_file)
                uverbs_uobject_put(&file->default_async_file->uobj);
        put_device(&file->device->dev);

        if (file->disassociate_page)
                __free_pages(file->disassociate_page, 0);
        mutex_destroy(&file->umap_lock);
        mutex_destroy(&file->ucontext_lock);
        kfree(file);
}

static ssize_t ib_uverbs_event_read(struct ib_uverbs_event_queue *ev_queue,
                                    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) ||
                                              ev_queue->is_closed)))
                        return -ERESTARTSYS;

                spin_lock_irq(&ev_queue->lock);

                /* If device was disassociated and no event exists set an error */
                if (list_empty(&ev_queue->event_list) && ev_queue->is_closed) {
                        spin_unlock_irq(&ev_queue->lock);
                        return -EIO;
                }
        }

        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, 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, filp, buf, count,
                                    pos,
                                    sizeof(struct ib_uverbs_comp_event_desc));
}

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

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

        spin_lock_irq(&ev_queue->lock);
        if (!list_empty(&ev_queue->event_list))
                pollflags = EPOLLIN | EPOLLRDNORM;
        else if (ev_queue->is_closed)
                pollflags = EPOLLERR;
        spin_unlock_irq(&ev_queue->lock);

        return pollflags;
}

static __poll_t ib_uverbs_async_event_poll(struct file *filp,
                                               struct poll_table_struct *wait)
{
        struct ib_uverbs_async_event_file *file = filp->private_data;

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

static __poll_t 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_async_event_file *file = filp->private_data;

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

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

const struct file_operations uverbs_async_event_fops = {
        .owner   = THIS_MODULE,
        .read    = ib_uverbs_async_event_read,
        .poll    = ib_uverbs_async_event_poll,
        .release = uverbs_async_event_release,
        .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 = cq->uobject;

        entry->desc.comp.cq_handle = cq->uobject->uevent.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);
}

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

        if (!async_file)
                return;

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

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

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

static void uverbs_uobj_event(struct ib_uevent_object *eobj,
                              struct ib_event *event)
{
        ib_uverbs_async_handler(eobj->event_file,
                                eobj->uobject.user_handle, event->event,
                                &eobj->event_list, &eobj->events_reported);
}

void ib_uverbs_cq_event_handler(struct ib_event *event, void *context_ptr)
{
        uverbs_uobj_event(&event->element.cq->uobject->uevent, event);
}

void ib_uverbs_qp_event_handler(struct ib_event *event, void *context_ptr)
{
        /* for XRC target qp's, check that qp is live */
        if (!event->element.qp->uobject)
                return;

        uverbs_uobj_event(&event->element.qp->uobject->uevent, event);
}

void ib_uverbs_wq_event_handler(struct ib_event *event, void *context_ptr)
{
        uverbs_uobj_event(&event->element.wq->uobject->uevent, event);
}

void ib_uverbs_srq_event_handler(struct ib_event *event, void *context_ptr)
{
        uverbs_uobj_event(&event->element.srq->uobject->uevent, event);
}

static void ib_uverbs_event_handler(struct ib_event_handler *handler,
                                    struct ib_event *event)
{
        ib_uverbs_async_handler(
                container_of(handler, struct ib_uverbs_async_event_file,
                             event_handler),
                event->element.port_num, event->event, NULL, 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;
}

void ib_uverbs_init_async_event_file(
        struct ib_uverbs_async_event_file *async_file)
{
        struct ib_uverbs_file *uverbs_file = async_file->uobj.ufile;
        struct ib_device *ib_dev = async_file->uobj.context->device;

        ib_uverbs_init_event_queue(&async_file->ev_queue);

        /* The first async_event_file becomes the default one for the file. */
        mutex_lock(&uverbs_file->ucontext_lock);
        if (!uverbs_file->default_async_file) {
                /* Pairs with the put in ib_uverbs_release_file */
                uverbs_uobject_get(&async_file->uobj);
                smp_store_release(&uverbs_file->default_async_file, async_file);
        }
        mutex_unlock(&uverbs_file->ucontext_lock);

        INIT_IB_EVENT_HANDLER(&async_file->event_handler, ib_dev,
                              ib_uverbs_event_handler);
        ib_register_event_handler(&async_file->event_handler);
}

static ssize_t verify_hdr(struct ib_uverbs_cmd_hdr *hdr,
                          struct ib_uverbs_ex_cmd_hdr *ex_hdr, size_t count,
                          const struct uverbs_api_write_method *method_elm)
{
        if (method_elm->is_ex) {
                count -= sizeof(*hdr) + sizeof(*ex_hdr);

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

                if (hdr->in_words * 8 < method_elm->req_size)
                        return -ENOSPC;

                if (ex_hdr->cmd_hdr_reserved)
                        return -EINVAL;

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

                        if (hdr->out_words * 8 < method_elm->resp_size)
                                return -ENOSPC;

                        if (!access_ok(u64_to_user_ptr(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;
                }

                return 0;
        }

        /* not extended command */
        if (hdr->in_words * 4 != count)
                return -EINVAL;

        if (count < method_elm->req_size + sizeof(hdr)) {
                /*
                 * rdma-core v18 and v19 have a bug where they send DESTROY_CQ
                 * with a 16 byte write instead of 24. Old kernels didn't
                 * check the size so they allowed this. Now that the size is
                 * checked provide a compatibility work around to not break
                 * those userspaces.
                 */
                if (hdr->command == IB_USER_VERBS_CMD_DESTROY_CQ &&
                    count == 16) {
                        hdr->in_words = 6;
                        return 0;
                }
                return -ENOSPC;
        }
        if (hdr->out_words * 4 < method_elm->resp_size)
                return -ENOSPC;

        return 0;
}

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;
        const struct uverbs_api_write_method *method_elm;
        struct uverbs_api *uapi = file->device->uapi;
        struct ib_uverbs_ex_cmd_hdr ex_hdr;
        struct ib_uverbs_cmd_hdr hdr;
        struct uverbs_attr_bundle bundle;
        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;

        method_elm = uapi_get_method(uapi, hdr.command);
        if (IS_ERR(method_elm))
                return PTR_ERR(method_elm);

        if (method_elm->is_ex) {
                if (count < (sizeof(hdr) + sizeof(ex_hdr)))
                        return -EINVAL;
                if (copy_from_user(&ex_hdr, buf + sizeof(hdr), sizeof(ex_hdr)))
                        return -EFAULT;
        }

        ret = verify_hdr(&hdr, &ex_hdr, count, method_elm);
        if (ret)
                return ret;

        srcu_key = srcu_read_lock(&file->device->disassociate_srcu);

        buf += sizeof(hdr);

        memset(bundle.attr_present, 0, sizeof(bundle.attr_present));
        bundle.ufile = file;
        bundle.context = NULL; /* only valid if bundle has uobject */
        bundle.uobject = NULL;
        if (!method_elm->is_ex) {
                size_t in_len = hdr.in_words * 4 - sizeof(hdr);
                size_t out_len = hdr.out_words * 4;
                u64 response = 0;

                if (method_elm->has_udata) {
                        bundle.driver_udata.inlen =
                                in_len - method_elm->req_size;
                        in_len = method_elm->req_size;
                        if (bundle.driver_udata.inlen)
                                bundle.driver_udata.inbuf = buf + in_len;
                        else
                                bundle.driver_udata.inbuf = NULL;
                } else {
                        memset(&bundle.driver_udata, 0,
                               sizeof(bundle.driver_udata));
                }

                if (method_elm->has_resp) {
                        /*
                         * The macros check that if has_resp is set
                         * then the command request structure starts
                         * with a '__aligned u64 response' member.
                         */
                        ret = get_user(response, (const u64 __user *)buf);
                        if (ret)
                                goto out_unlock;

                        if (method_elm->has_udata) {
                                bundle.driver_udata.outlen =
                                        out_len - method_elm->resp_size;
                                out_len = method_elm->resp_size;
                                if (bundle.driver_udata.outlen)
                                        bundle.driver_udata.outbuf =
                                                u64_to_user_ptr(response +
                                                                out_len);
                                else
                                        bundle.driver_udata.outbuf = NULL;
                        }
                } else {
                        bundle.driver_udata.outlen = 0;
                        bundle.driver_udata.outbuf = NULL;
                }

                ib_uverbs_init_udata_buf_or_null(
                        &bundle.ucore, buf, u64_to_user_ptr(response),
                        in_len, out_len);
        } else {
                buf += sizeof(ex_hdr);

                ib_uverbs_init_udata_buf_or_null(&bundle.ucore, buf,
                                        u64_to_user_ptr(ex_hdr.response),
                                        hdr.in_words * 8, hdr.out_words * 8);

                ib_uverbs_init_udata_buf_or_null(
                        &bundle.driver_udata, buf + bundle.ucore.inlen,
                        u64_to_user_ptr(ex_hdr.response) + bundle.ucore.outlen,
                        ex_hdr.provider_in_words * 8,
                        ex_hdr.provider_out_words * 8);

        }

        ret = method_elm->handler(&bundle);
        if (bundle.uobject)
                uverbs_finalize_object(bundle.uobject, UVERBS_ACCESS_NEW, true,
                                       !ret, &bundle);
out_unlock:
        srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
        return (ret) ? : count;
}

static const struct vm_operations_struct rdma_umap_ops;

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

        srcu_key = srcu_read_lock(&file->device->disassociate_srcu);
        ucontext = ib_uverbs_get_ucontext_file(file);
        if (IS_ERR(ucontext)) {
                ret = PTR_ERR(ucontext);
                goto out;
        }
        vma->vm_ops = &rdma_umap_ops;
        ret = ucontext->device->ops.mmap(ucontext, vma);
out:
        srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
        return ret;
}

/*
 * The VMA has been dup'd, initialize the vm_private_data with a new tracking
 * struct
 */
static void rdma_umap_open(struct vm_area_struct *vma)
{
        struct ib_uverbs_file *ufile = vma->vm_file->private_data;
        struct rdma_umap_priv *opriv = vma->vm_private_data;
        struct rdma_umap_priv *priv;

        if (!opriv)
                return;

        /* We are racing with disassociation */
        if (!down_read_trylock(&ufile->hw_destroy_rwsem))
                goto out_zap;
        /*
         * Disassociation already completed, the VMA should already be zapped.
         */
        if (!ufile->ucontext)
                goto out_unlock;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv)
                goto out_unlock;
        rdma_umap_priv_init(priv, vma, opriv->entry);

        up_read(&ufile->hw_destroy_rwsem);
        return;

out_unlock:
        up_read(&ufile->hw_destroy_rwsem);
out_zap:
        /*
         * We can't allow the VMA to be created with the actual IO pages, that
         * would break our API contract, and it can't be stopped at this
         * point, so zap it.
         */
        vma->vm_private_data = NULL;
        zap_vma_ptes(vma, vma->vm_start, vma->vm_end - vma->vm_start);
}

static void rdma_umap_close(struct vm_area_struct *vma)
{
        struct ib_uverbs_file *ufile = vma->vm_file->private_data;
        struct rdma_umap_priv *priv = vma->vm_private_data;

        if (!priv)
                return;

        /*
         * The vma holds a reference on the struct file that created it, which
         * in turn means that the ib_uverbs_file is guaranteed to exist at
         * this point.
         */
        mutex_lock(&ufile->umap_lock);
        if (priv->entry)
                rdma_user_mmap_entry_put(priv->entry);

        list_del(&priv->list);
        mutex_unlock(&ufile->umap_lock);
        kfree(priv);
}

/*
 * Once the zap_vma_ptes has been called touches to the VMA will come here and
 * we return a dummy writable zero page for all the pfns.
 */
static vm_fault_t rdma_umap_fault(struct vm_fault *vmf)
{
        struct ib_uverbs_file *ufile = vmf->vma->vm_file->private_data;
        struct rdma_umap_priv *priv = vmf->vma->vm_private_data;
        vm_fault_t ret = 0;

        if (!priv)
                return VM_FAULT_SIGBUS;

        /* Read only pages can just use the system zero page. */
        if (!(vmf->vma->vm_flags & (VM_WRITE | VM_MAYWRITE))) {
                vmf->page = ZERO_PAGE(vmf->address);
                get_page(vmf->page);
                return 0;
        }

        mutex_lock(&ufile->umap_lock);
        if (!ufile->disassociate_page)
                ufile->disassociate_page =
                        alloc_pages(vmf->gfp_mask | __GFP_ZERO, 0);

        if (ufile->disassociate_page) {
                /*
                 * This VMA is forced to always be shared so this doesn't have
                 * to worry about COW.
                 */
                vmf->page = ufile->disassociate_page;
                get_page(vmf->page);
        } else {
                ret = VM_FAULT_SIGBUS;
        }
        mutex_unlock(&ufile->umap_lock);

        return ret;
}

static const struct vm_operations_struct rdma_umap_ops = {
        .open = rdma_umap_open,
        .close = rdma_umap_close,
        .fault = rdma_umap_fault,
};

void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
{
        struct rdma_umap_priv *priv, *next_priv;

        lockdep_assert_held(&ufile->hw_destroy_rwsem);

        while (1) {
                struct mm_struct *mm = NULL;

                /* Get an arbitrary mm pointer that hasn't been cleaned yet */
                mutex_lock(&ufile->umap_lock);
                while (!list_empty(&ufile->umaps)) {
                        int ret;

                        priv = list_first_entry(&ufile->umaps,
                                                struct rdma_umap_priv, list);
                        mm = priv->vma->vm_mm;
                        ret = mmget_not_zero(mm);
                        if (!ret) {
                                list_del_init(&priv->list);
                                if (priv->entry) {
                                        rdma_user_mmap_entry_put(priv->entry);
                                        priv->entry = NULL;
                                }
                                mm = NULL;
                                continue;
                        }
                        break;
                }
                mutex_unlock(&ufile->umap_lock);
                if (!mm)
                        return;

                /*
                 * The umap_lock is nested under mmap_lock since it used within
                 * the vma_ops callbacks, so we have to clean the list one mm
                 * at a time to get the lock ordering right. Typically there
                 * will only be one mm, so no big deal.
                 */
                mmap_read_lock(mm);
                if (!mmget_still_valid(mm))
                        goto skip_mm;
                mutex_lock(&ufile->umap_lock);
                list_for_each_entry_safe (priv, next_priv, &ufile->umaps,
                                          list) {
                        struct vm_area_struct *vma = priv->vma;

                        if (vma->vm_mm != mm)
                                continue;
                        list_del_init(&priv->list);

                        zap_vma_ptes(vma, vma->vm_start,
                                     vma->vm_end - vma->vm_start);

                        if (priv->entry) {
                                rdma_user_mmap_entry_put(priv->entry);
                                priv->entry = NULL;
                        }
                }
                mutex_unlock(&ufile->umap_lock);
        skip_mm:
                mmap_read_unlock(mm);
                mmput(mm);
        }
}

/*
 * 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;

        get_device(&dev->dev);
        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;
        }

        if (!rdma_dev_access_netns(ib_dev, current->nsproxy->net_ns)) {
                ret = -EPERM;
                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->ops.disassociate_ucontext);

        if (module_dependent) {
                if (!try_module_get(ib_dev->ops.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;
        kref_init(&file->ref);
        mutex_init(&file->ucontext_lock);

        spin_lock_init(&file->uobjects_lock);
        INIT_LIST_HEAD(&file->uobjects);
        init_rwsem(&file->hw_destroy_rwsem);
        mutex_init(&file->umap_lock);
        INIT_LIST_HEAD(&file->umaps);

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

        setup_ufile_idr_uobject(file);

        return stream_open(inode, filp);

err_module:
        module_put(ib_dev->ops.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);

        put_device(&dev->dev);
        return ret;
}

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

        uverbs_destroy_ufile_hw(file, RDMA_REMOVE_CLOSE);

        mutex_lock(&file->device->lists_mutex);
        list_del_init(&file->list);
        mutex_unlock(&file->device->lists_mutex);

        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,
        .unlocked_ioctl = ib_uverbs_ioctl,
        .compat_ioctl = compat_ptr_ioctl,
};

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,
        .unlocked_ioctl = ib_uverbs_ioctl,
        .compat_ioctl = compat_ptr_ioctl,
};

static int ib_uverbs_get_nl_info(struct ib_device *ibdev, void *client_data,
                                 struct ib_client_nl_info *res)
{
        struct ib_uverbs_device *uverbs_dev = client_data;
        int ret;

        if (res->port != -1)
                return -EINVAL;

        res->abi = ibdev->ops.uverbs_abi_ver;
        res->cdev = &uverbs_dev->dev;

        /*
         * To support DRIVER_ID binding in userspace some of the driver need
         * upgrading to expose their PCI dependent revision information
         * through get_context instead of relying on modalias matching. When
         * the drivers are fixed they can drop this flag.
         */
        if (!ibdev->ops.uverbs_no_driver_id_binding) {
                ret = nla_put_u32(res->nl_msg, RDMA_NLDEV_ATTR_UVERBS_DRIVER_ID,
                                  ibdev->ops.driver_id);
                if (ret)
                        return ret;
        }
        return 0;
}

static struct ib_client uverbs_client = {
        .name   = "uverbs",
        .no_kverbs_req = true,
        .add    = ib_uverbs_add_one,
        .remove = ib_uverbs_remove_one,
        .get_nl_info = ib_uverbs_get_nl_info,
};
MODULE_ALIAS_RDMA_CLIENT("uverbs");

static ssize_t ibdev_show(struct device *device, struct device_attribute *attr,
                          char *buf)
{
        struct ib_uverbs_device *dev =
                        container_of(device, struct ib_uverbs_device, dev);
        int ret = -ENODEV;
        int srcu_key;
        struct ib_device *ib_dev;

        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", dev_name(&ib_dev->dev));
        srcu_read_unlock(&dev->disassociate_srcu, srcu_key);

        return ret;
}
static DEVICE_ATTR_RO(ibdev);

static ssize_t abi_version_show(struct device *device,
                                struct device_attribute *attr, char *buf)
{
        struct ib_uverbs_device *dev =
                        container_of(device, struct ib_uverbs_device, dev);
        int ret = -ENODEV;
        int srcu_key;
        struct ib_device *ib_dev;

        srcu_key = srcu_read_lock(&dev->disassociate_srcu);
        ib_dev = srcu_dereference(dev->ib_dev, &dev->disassociate_srcu);
        if (ib_dev)
                ret = sprintf(buf, "%u\n", ib_dev->ops.uverbs_abi_ver);
        srcu_read_unlock(&dev->disassociate_srcu, srcu_key);

        return ret;
}
static DEVICE_ATTR_RO(abi_version);

static struct attribute *ib_dev_attrs[] = {
        &dev_attr_abi_version.attr,
        &dev_attr_ibdev.attr,
        NULL,
};

static const struct attribute_group dev_attr_group = {
        .attrs = ib_dev_attrs,
};

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

static int ib_uverbs_create_uapi(struct ib_device *device,
                                 struct ib_uverbs_device *uverbs_dev)
{
        struct uverbs_api *uapi;

        uapi = uverbs_alloc_api(device);
        if (IS_ERR(uapi))
                return PTR_ERR(uapi);

        uverbs_dev->uapi = uapi;
        return 0;
}

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

        if (!device->ops.alloc_ucontext)
                return -EOPNOTSUPP;

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

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

        device_initialize(&uverbs_dev->dev);
        uverbs_dev->dev.class = uverbs_class;
        uverbs_dev->dev.parent = device->dev.parent;
        uverbs_dev->dev.release = ib_uverbs_release_dev;
        uverbs_dev->groups[0] = &dev_attr_group;
        uverbs_dev->dev.groups = uverbs_dev->groups;
        atomic_set(&uverbs_dev->refcount, 1);
        init_completion(&uverbs_dev->comp);
        uverbs_dev->xrcd_tree = RB_ROOT;
        mutex_init(&uverbs_dev->xrcd_tree_mutex);
        mutex_init(&uverbs_dev->lists_mutex);
        INIT_LIST_HEAD(&uverbs_dev->uverbs_file_list);
        rcu_assign_pointer(uverbs_dev->ib_dev, device);
        uverbs_dev->num_comp_vectors = device->num_comp_vectors;

        devnum = ida_alloc_max(&uverbs_ida, IB_UVERBS_MAX_DEVICES - 1,
                               GFP_KERNEL);
        if (devnum < 0) {
                ret = -ENOMEM;
                goto err;
        }
        uverbs_dev->devnum = devnum;
        if (devnum >= IB_UVERBS_NUM_FIXED_MINOR)
                base = dynamic_uverbs_dev + devnum - IB_UVERBS_NUM_FIXED_MINOR;
        else
                base = IB_UVERBS_BASE_DEV + devnum;

        ret = ib_uverbs_create_uapi(device, uverbs_dev);
        if (ret)
                goto err_uapi;

        uverbs_dev->dev.devt = base;
        dev_set_name(&uverbs_dev->dev, "uverbs%d", uverbs_dev->devnum);

        cdev_init(&uverbs_dev->cdev,
                  device->ops.mmap ? &uverbs_mmap_fops : &uverbs_fops);
        uverbs_dev->cdev.owner = THIS_MODULE;

        ret = cdev_device_add(&uverbs_dev->cdev, &uverbs_dev->dev);
        if (ret)
                goto err_uapi;

        ib_set_client_data(device, &uverbs_client, uverbs_dev);
        return 0;

err_uapi:
        ida_free(&uverbs_ida, devnum);
err:
        if (atomic_dec_and_test(&uverbs_dev->refcount))
                ib_uverbs_comp_dev(uverbs_dev);
        wait_for_completion(&uverbs_dev->comp);
        put_device(&uverbs_dev->dev);
        return ret;
}

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

        /* Pending running commands to terminate */
        uverbs_disassociate_api_pre(uverbs_dev);

        mutex_lock(&uverbs_dev->lists_mutex);
        while (!list_empty(&uverbs_dev->uverbs_file_list)) {
                file = list_first_entry(&uverbs_dev->uverbs_file_list,
                                        struct ib_uverbs_file, list);
                list_del_init(&file->list);
                kref_get(&file->ref);

                /* We must release the mutex before going ahead and calling
                 * uverbs_cleanup_ufile, as it might end up indirectly calling
                 * uverbs_close, for example due to freeing the resources (e.g
                 * mmput).
                 */
                mutex_unlock(&uverbs_dev->lists_mutex);

                uverbs_destroy_ufile_hw(file, RDMA_REMOVE_DRIVER_REMOVE);
                kref_put(&file->ref, ib_uverbs_release_file);

                mutex_lock(&uverbs_dev->lists_mutex);
        }
        mutex_unlock(&uverbs_dev->lists_mutex);

        uverbs_disassociate_api(uverbs_dev->uapi);
}

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;

        cdev_device_del(&uverbs_dev->cdev, &uverbs_dev->dev);
        ida_free(&uverbs_ida, uverbs_dev->devnum);

        if (device->ops.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.
                 */
                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);

        put_device(&uverbs_dev->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_NUM_FIXED_MINOR,
                                     "infiniband_verbs");
        if (ret) {
                pr_err("user_verbs: couldn't register device number\n");
                goto out;
        }

        ret = alloc_chrdev_region(&dynamic_uverbs_dev, 0,
                                  IB_UVERBS_NUM_DYNAMIC_MINOR,
                                  "infiniband_verbs");
        if (ret) {
                pr_err("couldn't register dynamic device number\n");
                goto out_alloc;
        }

        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(dynamic_uverbs_dev,
                                 IB_UVERBS_NUM_DYNAMIC_MINOR);

out_alloc:
        unregister_chrdev_region(IB_UVERBS_BASE_DEV,
                                 IB_UVERBS_NUM_FIXED_MINOR);

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_NUM_FIXED_MINOR);
        unregister_chrdev_region(dynamic_uverbs_dev,
                                 IB_UVERBS_NUM_DYNAMIC_MINOR);
        mmu_notifier_synchronize();
}

module_init(ib_uverbs_init);
module_exit(ib_uverbs_cleanup);