/*
 * Copyright 2017 Red Hat
 * Parts ported from amdgpu (fence wait code).
 * Copyright 2016 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * 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.
 *
 * Authors:
 *
 */

/**
 * DOC: Overview
 *
 * DRM synchronisation objects (syncobj, see struct &drm_syncobj) provide a
 * container for a synchronization primitive which can be used by userspace
 * to explicitly synchronize GPU commands, can be shared between userspace
 * processes, and can be shared between different DRM drivers.
 * Their primary use-case is to implement Vulkan fences and semaphores.
 * The syncobj userspace API provides ioctls for several operations:
 *
 *  - Creation and destruction of syncobjs
 *  - Import and export of syncobjs to/from a syncobj file descriptor
 *  - Import and export a syncobj's underlying fence to/from a sync file
 *  - Reset a syncobj (set its fence to NULL)
 *  - Signal a syncobj (set a trivially signaled fence)
 *  - Wait for a syncobj's fence to appear and be signaled
 *
 * The syncobj userspace API also provides operations to manipulate a syncobj
 * in terms of a timeline of struct &dma_fence_chain rather than a single
 * struct &dma_fence, through the following operations:
 *
 *   - Signal a given point on the timeline
 *   - Wait for a given point to appear and/or be signaled
 *   - Import and export from/to a given point of a timeline
 *
 * At it's core, a syncobj is simply a wrapper around a pointer to a struct
 * &dma_fence which may be NULL.
 * When a syncobj is first created, its pointer is either NULL or a pointer
 * to an already signaled fence depending on whether the
 * &DRM_SYNCOBJ_CREATE_SIGNALED flag is passed to
 * &DRM_IOCTL_SYNCOBJ_CREATE.
 *
 * If the syncobj is considered as a binary (its state is either signaled or
 * unsignaled) primitive, when GPU work is enqueued in a DRM driver to signal
 * the syncobj, the syncobj's fence is replaced with a fence which will be
 * signaled by the completion of that work.
 * If the syncobj is considered as a timeline primitive, when GPU work is
 * enqueued in a DRM driver to signal the a given point of the syncobj, a new
 * struct &dma_fence_chain pointing to the DRM driver's fence and also
 * pointing to the previous fence that was in the syncobj. The new struct
 * &dma_fence_chain fence replace the syncobj's fence and will be signaled by
 * completion of the DRM driver's work and also any work associated with the
 * fence previously in the syncobj.
 *
 * When GPU work which waits on a syncobj is enqueued in a DRM driver, at the
 * time the work is enqueued, it waits on the syncobj's fence before
 * submitting the work to hardware. That fence is either :
 *
 *    - The syncobj's current fence if the syncobj is considered as a binary
 *      primitive.
 *    - The struct &dma_fence associated with a given point if the syncobj is
 *      considered as a timeline primitive.
 *
 * If the syncobj's fence is NULL or not present in the syncobj's timeline,
 * the enqueue operation is expected to fail.
 *
 * With binary syncobj, all manipulation of the syncobjs's fence happens in
 * terms of the current fence at the time the ioctl is called by userspace
 * regardless of whether that operation is an immediate host-side operation
 * (signal or reset) or or an operation which is enqueued in some driver
 * queue. &DRM_IOCTL_SYNCOBJ_RESET and &DRM_IOCTL_SYNCOBJ_SIGNAL can be used
 * to manipulate a syncobj from the host by resetting its pointer to NULL or
 * setting its pointer to a fence which is already signaled.
 *
 * With a timeline syncobj, all manipulation of the synobj's fence happens in
 * terms of a u64 value referring to point in the timeline. See
 * dma_fence_chain_find_seqno() to see how a given point is found in the
 * timeline.
 *
 * Note that applications should be careful to always use timeline set of
 * ioctl() when dealing with syncobj considered as timeline. Using a binary
 * set of ioctl() with a syncobj considered as timeline could result incorrect
 * synchronization. The use of binary syncobj is supported through the
 * timeline set of ioctl() by using a point value of 0, this will reproduce
 * the behavior of the binary set of ioctl() (for example replace the
 * syncobj's fence when signaling).
 *
 *
 * Host-side wait on syncobjs
 * --------------------------
 *
 * &DRM_IOCTL_SYNCOBJ_WAIT takes an array of syncobj handles and does a
 * host-side wait on all of the syncobj fences simultaneously.
 * If &DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL is set, the wait ioctl will wait on
 * all of the syncobj fences to be signaled before it returns.
 * Otherwise, it returns once at least one syncobj fence has been signaled
 * and the index of a signaled fence is written back to the client.
 *
 * Unlike the enqueued GPU work dependencies which fail if they see a NULL
 * fence in a syncobj, if &DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT is set,
 * the host-side wait will first wait for the syncobj to receive a non-NULL
 * fence and then wait on that fence.
 * If &DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT is not set and any one of the
 * syncobjs in the array has a NULL fence, -EINVAL will be returned.
 * Assuming the syncobj starts off with a NULL fence, this allows a client
 * to do a host wait in one thread (or process) which waits on GPU work
 * submitted in another thread (or process) without having to manually
 * synchronize between the two.
 * This requirement is inherited from the Vulkan fence API.
 *
 * Similarly, &DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT takes an array of syncobj
 * handles as well as an array of u64 points and does a host-side wait on all
 * of syncobj fences at the given points simultaneously.
 *
 * &DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT also adds the ability to wait for a given
 * fence to materialize on the timeline without waiting for the fence to be
 * signaled by using the &DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE flag. This
 * requirement is inherited from the wait-before-signal behavior required by
 * the Vulkan timeline semaphore API.
 *
 *
 * Import/export of syncobjs
 * -------------------------
 *
 * &DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE and &DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD
 * provide two mechanisms for import/export of syncobjs.
 *
 * The first lets the client import or export an entire syncobj to a file
 * descriptor.
 * These fd's are opaque and have no other use case, except passing the
 * syncobj between processes.
 * All exported file descriptors and any syncobj handles created as a
 * result of importing those file descriptors own a reference to the
 * same underlying struct &drm_syncobj and the syncobj can be used
 * persistently across all the processes with which it is shared.
 * The syncobj is freed only once the last reference is dropped.
 * Unlike dma-buf, importing a syncobj creates a new handle (with its own
 * reference) for every import instead of de-duplicating.
 * The primary use-case of this persistent import/export is for shared
 * Vulkan fences and semaphores.
 *
 * The second import/export mechanism, which is indicated by
 * &DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE or
 * &DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE lets the client
 * import/export the syncobj's current fence from/to a &sync_file.
 * When a syncobj is exported to a sync file, that sync file wraps the
 * sycnobj's fence at the time of export and any later signal or reset
 * operations on the syncobj will not affect the exported sync file.
 * When a sync file is imported into a syncobj, the syncobj's fence is set
 * to the fence wrapped by that sync file.
 * Because sync files are immutable, resetting or signaling the syncobj
 * will not affect any sync files whose fences have been imported into the
 * syncobj.
 *
 *
 * Import/export of timeline points in timeline syncobjs
 * -----------------------------------------------------
 *
 * &DRM_IOCTL_SYNCOBJ_TRANSFER provides a mechanism to transfer a struct
 * &dma_fence_chain of a syncobj at a given u64 point to another u64 point
 * into another syncobj.
 *
 * Note that if you want to transfer a struct &dma_fence_chain from a given
 * point on a timeline syncobj from/into a binary syncobj, you can use the
 * point 0 to mean take/replace the fence in the syncobj.
 */

#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/sched/signal.h>
#include <linux/sync_file.h>
#include <linux/uaccess.h>

#include <drm/drm.h>
#include <drm/drm_drv.h>
#include <drm/drm_file.h>
#include <drm/drm_gem.h>
#include <drm/drm_print.h>
#include <drm/drm_syncobj.h>
#include <drm/drm_utils.h>

#include "drm_internal.h"

struct syncobj_wait_entry {
        struct list_head node;
        struct task_struct *task;
        struct dma_fence *fence;
        struct dma_fence_cb fence_cb;
        u64    point;
};

static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
                                      struct syncobj_wait_entry *wait);

/**
 * drm_syncobj_find - lookup and reference a sync object.
 * @file_private: drm file private pointer
 * @handle: sync object handle to lookup.
 *
 * Returns a reference to the syncobj pointed to by handle or NULL. The
 * reference must be released by calling drm_syncobj_put().
 */
struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
                                     u32 handle)
{
        struct drm_syncobj *syncobj;

        spin_lock(&file_private->syncobj_table_lock);

        /* Check if we currently have a reference on the object */
        syncobj = idr_find(&file_private->syncobj_idr, handle);
        if (syncobj)
                drm_syncobj_get(syncobj);

        spin_unlock(&file_private->syncobj_table_lock);

        return syncobj;
}
EXPORT_SYMBOL(drm_syncobj_find);

static void drm_syncobj_fence_add_wait(struct drm_syncobj *syncobj,
                                       struct syncobj_wait_entry *wait)
{
        struct dma_fence *fence;

        if (wait->fence)
                return;

        spin_lock(&syncobj->lock);
        /* We've already tried once to get a fence and failed.  Now that we
         * have the lock, try one more time just to be sure we don't add a
         * callback when a fence has already been set.
         */
        fence = dma_fence_get(rcu_dereference_protected(syncobj->fence, 1));
        if (!fence || dma_fence_chain_find_seqno(&fence, wait->point)) {
                dma_fence_put(fence);
                list_add_tail(&wait->node, &syncobj->cb_list);
        } else if (!fence) {
                wait->fence = dma_fence_get_stub();
        } else {
                wait->fence = fence;
        }
        spin_unlock(&syncobj->lock);
}

static void drm_syncobj_remove_wait(struct drm_syncobj *syncobj,
                                    struct syncobj_wait_entry *wait)
{
        if (!wait->node.next)
                return;

        spin_lock(&syncobj->lock);
        list_del_init(&wait->node);
        spin_unlock(&syncobj->lock);
}

/**
 * drm_syncobj_add_point - add new timeline point to the syncobj
 * @syncobj: sync object to add timeline point do
 * @chain: chain node to use to add the point
 * @fence: fence to encapsulate in the chain node
 * @point: sequence number to use for the point
 *
 * Add the chain node as new timeline point to the syncobj.
 */
void drm_syncobj_add_point(struct drm_syncobj *syncobj,
                           struct dma_fence_chain *chain,
                           struct dma_fence *fence,
                           uint64_t point)
{
        struct syncobj_wait_entry *cur, *tmp;
        struct dma_fence *prev;

        dma_fence_get(fence);

        spin_lock(&syncobj->lock);

        prev = drm_syncobj_fence_get(syncobj);
        /* You are adding an unorder point to timeline, which could cause payload returned from query_ioctl is 0! */
        if (prev && prev->seqno >= point)
                DRM_DEBUG("You are adding an unorder point to timeline!\n");
        dma_fence_chain_init(chain, prev, fence, point);
        rcu_assign_pointer(syncobj->fence, &chain->base);

        list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node)
                syncobj_wait_syncobj_func(syncobj, cur);
        spin_unlock(&syncobj->lock);

        /* Walk the chain once to trigger garbage collection */
        dma_fence_chain_for_each(fence, prev);
        dma_fence_put(prev);
}
EXPORT_SYMBOL(drm_syncobj_add_point);

/**
 * drm_syncobj_replace_fence - replace fence in a sync object.
 * @syncobj: Sync object to replace fence in
 * @fence: fence to install in sync file.
 *
 * This replaces the fence on a sync object.
 */
void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
                               struct dma_fence *fence)
{
        struct dma_fence *old_fence;
        struct syncobj_wait_entry *cur, *tmp;

        if (fence)
                dma_fence_get(fence);

        spin_lock(&syncobj->lock);

        old_fence = rcu_dereference_protected(syncobj->fence,
                                              lockdep_is_held(&syncobj->lock));
        rcu_assign_pointer(syncobj->fence, fence);

        if (fence != old_fence) {
                list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node)
                        syncobj_wait_syncobj_func(syncobj, cur);
        }

        spin_unlock(&syncobj->lock);

        dma_fence_put(old_fence);
}
EXPORT_SYMBOL(drm_syncobj_replace_fence);

/**
 * drm_syncobj_assign_null_handle - assign a stub fence to the sync object
 * @syncobj: sync object to assign the fence on
 *
 * Assign a already signaled stub fence to the sync object.
 */
static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
{
        struct dma_fence *fence = dma_fence_allocate_private_stub();

        if (IS_ERR(fence))
                return PTR_ERR(fence);

        drm_syncobj_replace_fence(syncobj, fence);
        dma_fence_put(fence);
        return 0;
}

/* 5s default for wait submission */
#define DRM_SYNCOBJ_WAIT_FOR_SUBMIT_TIMEOUT 5000000000ULL
/**
 * drm_syncobj_find_fence - lookup and reference the fence in a sync object
 * @file_private: drm file private pointer
 * @handle: sync object handle to lookup.
 * @point: timeline point
 * @flags: DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT or not
 * @fence: out parameter for the fence
 *
 * This is just a convenience function that combines drm_syncobj_find() and
 * drm_syncobj_fence_get().
 *
 * Returns 0 on success or a negative error value on failure. On success @fence
 * contains a reference to the fence, which must be released by calling
 * dma_fence_put().
 */
int drm_syncobj_find_fence(struct drm_file *file_private,
                           u32 handle, u64 point, u64 flags,
                           struct dma_fence **fence)
{
        struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
        struct syncobj_wait_entry wait;
        u64 timeout = nsecs_to_jiffies64(DRM_SYNCOBJ_WAIT_FOR_SUBMIT_TIMEOUT);
        int ret;

        if (!syncobj)
                return -ENOENT;

        /* Waiting for userspace with locks help is illegal cause that can
         * trivial deadlock with page faults for example. Make lockdep complain
         * about it early on.
         */
        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
                might_sleep();
                lockdep_assert_none_held_once();
        }

        *fence = drm_syncobj_fence_get(syncobj);

        if (*fence) {
                ret = dma_fence_chain_find_seqno(fence, point);
                if (!ret)
                        goto out;
                dma_fence_put(*fence);
        } else {
                ret = -EINVAL;
        }

        if (!(flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
                goto out;

        memset(&wait, 0, sizeof(wait));
        wait.task = current;
        wait.point = point;
        drm_syncobj_fence_add_wait(syncobj, &wait);

        do {
                set_current_state(TASK_INTERRUPTIBLE);
                if (wait.fence) {
                        ret = 0;
                        break;
                }
                if (timeout == 0) {
                        ret = -ETIME;
                        break;
                }

                if (signal_pending(current)) {
                        ret = -ERESTARTSYS;
                        break;
                }

                timeout = schedule_timeout(timeout);
        } while (1);

        __set_current_state(TASK_RUNNING);
        *fence = wait.fence;

        if (wait.node.next)
                drm_syncobj_remove_wait(syncobj, &wait);

out:
        drm_syncobj_put(syncobj);

        return ret;
}
EXPORT_SYMBOL(drm_syncobj_find_fence);

/**
 * drm_syncobj_free - free a sync object.
 * @kref: kref to free.
 *
 * Only to be called from kref_put in drm_syncobj_put.
 */
void drm_syncobj_free(struct kref *kref)
{
        struct drm_syncobj *syncobj = container_of(kref,
                                                   struct drm_syncobj,
                                                   refcount);
        drm_syncobj_replace_fence(syncobj, NULL);
        kfree(syncobj);
}
EXPORT_SYMBOL(drm_syncobj_free);

/**
 * drm_syncobj_create - create a new syncobj
 * @out_syncobj: returned syncobj
 * @flags: DRM_SYNCOBJ_* flags
 * @fence: if non-NULL, the syncobj will represent this fence
 *
 * This is the first function to create a sync object. After creating, drivers
 * probably want to make it available to userspace, either through
 * drm_syncobj_get_handle() or drm_syncobj_get_fd().
 *
 * Returns 0 on success or a negative error value on failure.
 */
int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
                       struct dma_fence *fence)
{
        int ret;
        struct drm_syncobj *syncobj;

        syncobj = kzalloc(sizeof(struct drm_syncobj), GFP_KERNEL);
        if (!syncobj)
                return -ENOMEM;

        kref_init(&syncobj->refcount);
        INIT_LIST_HEAD(&syncobj->cb_list);
        spin_lock_init(&syncobj->lock);

        if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
                ret = drm_syncobj_assign_null_handle(syncobj);
                if (ret < 0) {
                        drm_syncobj_put(syncobj);
                        return ret;
                }
        }

        if (fence)
                drm_syncobj_replace_fence(syncobj, fence);

        *out_syncobj = syncobj;
        return 0;
}
EXPORT_SYMBOL(drm_syncobj_create);

/**
 * drm_syncobj_get_handle - get a handle from a syncobj
 * @file_private: drm file private pointer
 * @syncobj: Sync object to export
 * @handle: out parameter with the new handle
 *
 * Exports a sync object created with drm_syncobj_create() as a handle on
 * @file_private to userspace.
 *
 * Returns 0 on success or a negative error value on failure.
 */
int drm_syncobj_get_handle(struct drm_file *file_private,
                           struct drm_syncobj *syncobj, u32 *handle)
{
        int ret;

        /* take a reference to put in the idr */
        drm_syncobj_get(syncobj);

        idr_preload(GFP_KERNEL);
        spin_lock(&file_private->syncobj_table_lock);
        ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
        spin_unlock(&file_private->syncobj_table_lock);

        idr_preload_end();

        if (ret < 0) {
                drm_syncobj_put(syncobj);
                return ret;
        }

        *handle = ret;
        return 0;
}
EXPORT_SYMBOL(drm_syncobj_get_handle);

static int drm_syncobj_create_as_handle(struct drm_file *file_private,
                                        u32 *handle, uint32_t flags)
{
        int ret;
        struct drm_syncobj *syncobj;

        ret = drm_syncobj_create(&syncobj, flags, NULL);
        if (ret)
                return ret;

        ret = drm_syncobj_get_handle(file_private, syncobj, handle);
        drm_syncobj_put(syncobj);
        return ret;
}

static int drm_syncobj_destroy(struct drm_file *file_private,
                               u32 handle)
{
        struct drm_syncobj *syncobj;

        spin_lock(&file_private->syncobj_table_lock);
        syncobj = idr_remove(&file_private->syncobj_idr, handle);
        spin_unlock(&file_private->syncobj_table_lock);

        if (!syncobj)
                return -EINVAL;

        drm_syncobj_put(syncobj);
        return 0;
}

static int drm_syncobj_file_release(struct inode *inode, struct file *file)
{
        struct drm_syncobj *syncobj = file->private_data;

        drm_syncobj_put(syncobj);
        return 0;
}

static const struct file_operations drm_syncobj_file_fops = {
        .release = drm_syncobj_file_release,
};

/**
 * drm_syncobj_get_fd - get a file descriptor from a syncobj
 * @syncobj: Sync object to export
 * @p_fd: out parameter with the new file descriptor
 *
 * Exports a sync object created with drm_syncobj_create() as a file descriptor.
 *
 * Returns 0 on success or a negative error value on failure.
 */
int drm_syncobj_get_fd(struct drm_syncobj *syncobj, int *p_fd)
{
        struct file *file;
        int fd;

        fd = get_unused_fd_flags(O_CLOEXEC);
        if (fd < 0)
                return fd;

        file = anon_inode_getfile("syncobj_file",
                                  &drm_syncobj_file_fops,
                                  syncobj, 0);
        if (IS_ERR(file)) {
                put_unused_fd(fd);
                return PTR_ERR(file);
        }

        drm_syncobj_get(syncobj);
        fd_install(fd, file);

        *p_fd = fd;
        return 0;
}
EXPORT_SYMBOL(drm_syncobj_get_fd);

static int drm_syncobj_handle_to_fd(struct drm_file *file_private,
                                    u32 handle, int *p_fd)
{
        struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
        int ret;

        if (!syncobj)
                return -EINVAL;

        ret = drm_syncobj_get_fd(syncobj, p_fd);
        drm_syncobj_put(syncobj);
        return ret;
}

static int drm_syncobj_fd_to_handle(struct drm_file *file_private,
                                    int fd, u32 *handle)
{
        struct drm_syncobj *syncobj;
        struct fd f = fdget(fd);
        int ret;

        if (!f.file)
                return -EINVAL;

        if (f.file->f_op != &drm_syncobj_file_fops) {
                fdput(f);
                return -EINVAL;
        }

        /* take a reference to put in the idr */
        syncobj = f.file->private_data;
        drm_syncobj_get(syncobj);

        idr_preload(GFP_KERNEL);
        spin_lock(&file_private->syncobj_table_lock);
        ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
        spin_unlock(&file_private->syncobj_table_lock);
        idr_preload_end();

        if (ret > 0) {
                *handle = ret;
                ret = 0;
        } else
                drm_syncobj_put(syncobj);

        fdput(f);
        return ret;
}

static int drm_syncobj_import_sync_file_fence(struct drm_file *file_private,
                                              int fd, int handle)
{
        struct dma_fence *fence = sync_file_get_fence(fd);
        struct drm_syncobj *syncobj;

        if (!fence)
                return -EINVAL;

        syncobj = drm_syncobj_find(file_private, handle);
        if (!syncobj) {
                dma_fence_put(fence);
                return -ENOENT;
        }

        drm_syncobj_replace_fence(syncobj, fence);
        dma_fence_put(fence);
        drm_syncobj_put(syncobj);
        return 0;
}

static int drm_syncobj_export_sync_file(struct drm_file *file_private,
                                        int handle, int *p_fd)
{
        int ret;
        struct dma_fence *fence;
        struct sync_file *sync_file;
        int fd = get_unused_fd_flags(O_CLOEXEC);

        if (fd < 0)
                return fd;

        ret = drm_syncobj_find_fence(file_private, handle, 0, 0, &fence);
        if (ret)
                goto err_put_fd;

        sync_file = sync_file_create(fence);

        dma_fence_put(fence);

        if (!sync_file) {
                ret = -EINVAL;
                goto err_put_fd;
        }

        fd_install(fd, sync_file->file);

        *p_fd = fd;
        return 0;
err_put_fd:
        put_unused_fd(fd);
        return ret;
}
/**
 * drm_syncobj_open - initalizes syncobj file-private structures at devnode open time
 * @file_private: drm file-private structure to set up
 *
 * Called at device open time, sets up the structure for handling refcounting
 * of sync objects.
 */
void
drm_syncobj_open(struct drm_file *file_private)
{
        idr_init_base(&file_private->syncobj_idr, 1);
        spin_lock_init(&file_private->syncobj_table_lock);
}

static int
drm_syncobj_release_handle(int id, void *ptr, void *data)
{
        struct drm_syncobj *syncobj = ptr;

        drm_syncobj_put(syncobj);
        return 0;
}

/**
 * drm_syncobj_release - release file-private sync object resources
 * @file_private: drm file-private structure to clean up
 *
 * Called at close time when the filp is going away.
 *
 * Releases any remaining references on objects by this filp.
 */
void
drm_syncobj_release(struct drm_file *file_private)
{
        idr_for_each(&file_private->syncobj_idr,
                     &drm_syncobj_release_handle, file_private);
        idr_destroy(&file_private->syncobj_idr);
}

int
drm_syncobj_create_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file_private)
{
        struct drm_syncobj_create *args = data;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
                return -EOPNOTSUPP;

        /* no valid flags yet */
        if (args->flags & ~DRM_SYNCOBJ_CREATE_SIGNALED)
                return -EINVAL;

        return drm_syncobj_create_as_handle(file_private,
                                            &args->handle, args->flags);
}

int
drm_syncobj_destroy_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file_private)
{
        struct drm_syncobj_destroy *args = data;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
                return -EOPNOTSUPP;

        /* make sure padding is empty */
        if (args->pad)
                return -EINVAL;
        return drm_syncobj_destroy(file_private, args->handle);
}

int
drm_syncobj_handle_to_fd_ioctl(struct drm_device *dev, void *data,
                                   struct drm_file *file_private)
{
        struct drm_syncobj_handle *args = data;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
                return -EOPNOTSUPP;

        if (args->pad)
                return -EINVAL;

        if (args->flags != 0 &&
            args->flags != DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
                return -EINVAL;

        if (args->flags & DRM_SYNCOBJ_HANDLE_TO_FD_FLAGS_EXPORT_SYNC_FILE)
                return drm_syncobj_export_sync_file(file_private, args->handle,
                                                    &args->fd);

        return drm_syncobj_handle_to_fd(file_private, args->handle,
                                        &args->fd);
}

int
drm_syncobj_fd_to_handle_ioctl(struct drm_device *dev, void *data,
                                   struct drm_file *file_private)
{
        struct drm_syncobj_handle *args = data;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
                return -EOPNOTSUPP;

        if (args->pad)
                return -EINVAL;

        if (args->flags != 0 &&
            args->flags != DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE)
                return -EINVAL;

        if (args->flags & DRM_SYNCOBJ_FD_TO_HANDLE_FLAGS_IMPORT_SYNC_FILE)
                return drm_syncobj_import_sync_file_fence(file_private,
                                                          args->fd,
                                                          args->handle);

        return drm_syncobj_fd_to_handle(file_private, args->fd,
                                        &args->handle);
}

static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private,
                                            struct drm_syncobj_transfer *args)
{
        struct drm_syncobj *timeline_syncobj = NULL;
        struct dma_fence *fence;
        struct dma_fence_chain *chain;
        int ret;

        timeline_syncobj = drm_syncobj_find(file_private, args->dst_handle);
        if (!timeline_syncobj) {
                return -ENOENT;
        }
        ret = drm_syncobj_find_fence(file_private, args->src_handle,
                                     args->src_point, args->flags,
                                     &fence);
        if (ret)
                goto err;
        chain = kzalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
        if (!chain) {
                ret = -ENOMEM;
                goto err1;
        }
        drm_syncobj_add_point(timeline_syncobj, chain, fence, args->dst_point);
err1:
        dma_fence_put(fence);
err:
        drm_syncobj_put(timeline_syncobj);

        return ret;
}

static int
drm_syncobj_transfer_to_binary(struct drm_file *file_private,
                               struct drm_syncobj_transfer *args)
{
        struct drm_syncobj *binary_syncobj = NULL;
        struct dma_fence *fence;
        int ret;

        binary_syncobj = drm_syncobj_find(file_private, args->dst_handle);
        if (!binary_syncobj)
                return -ENOENT;
        ret = drm_syncobj_find_fence(file_private, args->src_handle,
                                     args->src_point, args->flags, &fence);
        if (ret)
                goto err;
        drm_syncobj_replace_fence(binary_syncobj, fence);
        dma_fence_put(fence);
err:
        drm_syncobj_put(binary_syncobj);

        return ret;
}
int
drm_syncobj_transfer_ioctl(struct drm_device *dev, void *data,
                           struct drm_file *file_private)
{
        struct drm_syncobj_transfer *args = data;
        int ret;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
                return -EOPNOTSUPP;

        if (args->pad)
                return -EINVAL;

        if (args->dst_point)
                ret = drm_syncobj_transfer_to_timeline(file_private, args);
        else
                ret = drm_syncobj_transfer_to_binary(file_private, args);

        return ret;
}

static void syncobj_wait_fence_func(struct dma_fence *fence,
                                    struct dma_fence_cb *cb)
{
        struct syncobj_wait_entry *wait =
                container_of(cb, struct syncobj_wait_entry, fence_cb);

        wake_up_process(wait->task);
}

static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
                                      struct syncobj_wait_entry *wait)
{
        struct dma_fence *fence;

        /* This happens inside the syncobj lock */
        fence = rcu_dereference_protected(syncobj->fence,
                                          lockdep_is_held(&syncobj->lock));
        dma_fence_get(fence);
        if (!fence || dma_fence_chain_find_seqno(&fence, wait->point)) {
                dma_fence_put(fence);
                return;
        } else if (!fence) {
                wait->fence = dma_fence_get_stub();
        } else {
                wait->fence = fence;
        }

        wake_up_process(wait->task);
        list_del_init(&wait->node);
}

static signed long drm_syncobj_array_wait_timeout(struct drm_syncobj **syncobjs,
                                                  void __user *user_points,
                                                  uint32_t count,
                                                  uint32_t flags,
                                                  signed long timeout,
                                                  uint32_t *idx)
{
        struct syncobj_wait_entry *entries;
        struct dma_fence *fence;
        uint64_t *points;
        uint32_t signaled_count, i;

        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT)
                lockdep_assert_none_held_once();

        points = kmalloc_array(count, sizeof(*points), GFP_KERNEL);
        if (points == NULL)
                return -ENOMEM;

        if (!user_points) {
                memset(points, 0, count * sizeof(uint64_t));

        } else if (copy_from_user(points, user_points,
                                  sizeof(uint64_t) * count)) {
                timeout = -EFAULT;
                goto err_free_points;
        }

        entries = kcalloc(count, sizeof(*entries), GFP_KERNEL);
        if (!entries) {
                timeout = -ENOMEM;
                goto err_free_points;
        }
        /* Walk the list of sync objects and initialize entries.  We do
         * this up-front so that we can properly return -EINVAL if there is
         * a syncobj with a missing fence and then never have the chance of
         * returning -EINVAL again.
         */
        signaled_count = 0;
        for (i = 0; i < count; ++i) {
                struct dma_fence *fence;

                entries[i].task = current;
                entries[i].point = points[i];
                fence = drm_syncobj_fence_get(syncobjs[i]);
                if (!fence || dma_fence_chain_find_seqno(&fence, points[i])) {
                        dma_fence_put(fence);
                        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
                                continue;

                        } else {
                                timeout = -EINVAL;
                                goto cleanup_entries;
                        }
                }

                if (fence)
                        entries[i].fence = fence;
                else
                        entries[i].fence = dma_fence_get_stub();

                if ((flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE) ||
                    dma_fence_is_signaled(entries[i].fence)) {
                        if (signaled_count == 0 && idx)
                                *idx = i;
                        signaled_count++;
                }
        }

        if (signaled_count == count ||
            (signaled_count > 0 &&
             !(flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL)))
                goto cleanup_entries;

        /* There's a very annoying laxness in the dma_fence API here, in
         * that backends are not required to automatically report when a
         * fence is signaled prior to fence->ops->enable_signaling() being
         * called.  So here if we fail to match signaled_count, we need to
         * fallthough and try a 0 timeout wait!
         */

        if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT) {
                for (i = 0; i < count; ++i)
                        drm_syncobj_fence_add_wait(syncobjs[i], &entries[i]);
        }

        do {
                set_current_state(TASK_INTERRUPTIBLE);

                signaled_count = 0;
                for (i = 0; i < count; ++i) {
                        fence = entries[i].fence;
                        if (!fence)
                                continue;

                        if ((flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE) ||
                            dma_fence_is_signaled(fence) ||
                            (!entries[i].fence_cb.func &&
                             dma_fence_add_callback(fence,
                                                    &entries[i].fence_cb,
                                                    syncobj_wait_fence_func))) {
                                /* The fence has been signaled */
                                if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL) {
                                        signaled_count++;
                                } else {
                                        if (idx)
                                                *idx = i;
                                        goto done_waiting;
                                }
                        }
                }

                if (signaled_count == count)
                        goto done_waiting;

                if (timeout == 0) {
                        timeout = -ETIME;
                        goto done_waiting;
                }

                if (signal_pending(current)) {
                        timeout = -ERESTARTSYS;
                        goto done_waiting;
                }

                timeout = schedule_timeout(timeout);
        } while (1);

done_waiting:
        __set_current_state(TASK_RUNNING);

cleanup_entries:
        for (i = 0; i < count; ++i) {
                drm_syncobj_remove_wait(syncobjs[i], &entries[i]);
                if (entries[i].fence_cb.func)
                        dma_fence_remove_callback(entries[i].fence,
                                                  &entries[i].fence_cb);
                dma_fence_put(entries[i].fence);
        }
        kfree(entries);

err_free_points:
        kfree(points);

        return timeout;
}

/**
 * drm_timeout_abs_to_jiffies - calculate jiffies timeout from absolute value
 *
 * @timeout_nsec: timeout nsec component in ns, 0 for poll
 *
 * Calculate the timeout in jiffies from an absolute time in sec/nsec.
 */
signed long drm_timeout_abs_to_jiffies(int64_t timeout_nsec)
{
        ktime_t abs_timeout, now;
        u64 timeout_ns, timeout_jiffies64;

        /* make 0 timeout means poll - absolute 0 doesn't seem valid */
        if (timeout_nsec == 0)
                return 0;

        abs_timeout = ns_to_ktime(timeout_nsec);
        now = ktime_get();

        if (!ktime_after(abs_timeout, now))
                return 0;

        timeout_ns = ktime_to_ns(ktime_sub(abs_timeout, now));

        timeout_jiffies64 = nsecs_to_jiffies64(timeout_ns);
        /*  clamp timeout to avoid infinite timeout */
        if (timeout_jiffies64 >= MAX_SCHEDULE_TIMEOUT - 1)
                return MAX_SCHEDULE_TIMEOUT - 1;

        return timeout_jiffies64 + 1;
}
EXPORT_SYMBOL(drm_timeout_abs_to_jiffies);

static int drm_syncobj_array_wait(struct drm_device *dev,
                                  struct drm_file *file_private,
                                  struct drm_syncobj_wait *wait,
                                  struct drm_syncobj_timeline_wait *timeline_wait,
                                  struct drm_syncobj **syncobjs, bool timeline)
{
        signed long timeout = 0;
        uint32_t first = ~0;

        if (!timeline) {
                timeout = drm_timeout_abs_to_jiffies(wait->timeout_nsec);
                timeout = drm_syncobj_array_wait_timeout(syncobjs,
                                                         NULL,
                                                         wait->count_handles,
                                                         wait->flags,
                                                         timeout, &first);
                if (timeout < 0)
                        return timeout;
                wait->first_signaled = first;
        } else {
                timeout = drm_timeout_abs_to_jiffies(timeline_wait->timeout_nsec);
                timeout = drm_syncobj_array_wait_timeout(syncobjs,
                                                         u64_to_user_ptr(timeline_wait->points),
                                                         timeline_wait->count_handles,
                                                         timeline_wait->flags,
                                                         timeout, &first);
                if (timeout < 0)
                        return timeout;
                timeline_wait->first_signaled = first;
        }
        return 0;
}

static int drm_syncobj_array_find(struct drm_file *file_private,
                                  void __user *user_handles,
                                  uint32_t count_handles,
                                  struct drm_syncobj ***syncobjs_out)
{
        uint32_t i, *handles;
        struct drm_syncobj **syncobjs;
        int ret;

        handles = kmalloc_array(count_handles, sizeof(*handles), GFP_KERNEL);
        if (handles == NULL)
                return -ENOMEM;

        if (copy_from_user(handles, user_handles,
                           sizeof(uint32_t) * count_handles)) {
                ret = -EFAULT;
                goto err_free_handles;
        }

        syncobjs = kmalloc_array(count_handles, sizeof(*syncobjs), GFP_KERNEL);
        if (syncobjs == NULL) {
                ret = -ENOMEM;
                goto err_free_handles;
        }

        for (i = 0; i < count_handles; i++) {
                syncobjs[i] = drm_syncobj_find(file_private, handles[i]);
                if (!syncobjs[i]) {
                        ret = -ENOENT;
                        goto err_put_syncobjs;
                }
        }

        kfree(handles);
        *syncobjs_out = syncobjs;
        return 0;

err_put_syncobjs:
        while (i-- > 0)
                drm_syncobj_put(syncobjs[i]);
        kfree(syncobjs);
err_free_handles:
        kfree(handles);

        return ret;
}

static void drm_syncobj_array_free(struct drm_syncobj **syncobjs,
                                   uint32_t count)
{
        uint32_t i;

        for (i = 0; i < count; i++)
                drm_syncobj_put(syncobjs[i]);
        kfree(syncobjs);
}

int
drm_syncobj_wait_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_private)
{
        struct drm_syncobj_wait *args = data;
        struct drm_syncobj **syncobjs;
        int ret = 0;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
                return -EOPNOTSUPP;

        if (args->flags & ~(DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
                            DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT))
                return -EINVAL;

        if (args->count_handles == 0)
                return -EINVAL;

        ret = drm_syncobj_array_find(file_private,
                                     u64_to_user_ptr(args->handles),
                                     args->count_handles,
                                     &syncobjs);
        if (ret < 0)
                return ret;

        ret = drm_syncobj_array_wait(dev, file_private,
                                     args, NULL, syncobjs, false);

        drm_syncobj_array_free(syncobjs, args->count_handles);

        return ret;
}

int
drm_syncobj_timeline_wait_ioctl(struct drm_device *dev, void *data,
                                struct drm_file *file_private)
{
        struct drm_syncobj_timeline_wait *args = data;
        struct drm_syncobj **syncobjs;
        int ret = 0;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
                return -EOPNOTSUPP;

        if (args->flags & ~(DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL |
                            DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT |
                            DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE))
                return -EINVAL;

        if (args->count_handles == 0)
                return -EINVAL;

        ret = drm_syncobj_array_find(file_private,
                                     u64_to_user_ptr(args->handles),
                                     args->count_handles,
                                     &syncobjs);
        if (ret < 0)
                return ret;

        ret = drm_syncobj_array_wait(dev, file_private,
                                     NULL, args, syncobjs, true);

        drm_syncobj_array_free(syncobjs, args->count_handles);

        return ret;
}


int
drm_syncobj_reset_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_private)
{
        struct drm_syncobj_array *args = data;
        struct drm_syncobj **syncobjs;
        uint32_t i;
        int ret;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
                return -EOPNOTSUPP;

        if (args->pad != 0)
                return -EINVAL;

        if (args->count_handles == 0)
                return -EINVAL;

        ret = drm_syncobj_array_find(file_private,
                                     u64_to_user_ptr(args->handles),
                                     args->count_handles,
                                     &syncobjs);
        if (ret < 0)
                return ret;

        for (i = 0; i < args->count_handles; i++)
                drm_syncobj_replace_fence(syncobjs[i], NULL);

        drm_syncobj_array_free(syncobjs, args->count_handles);

        return 0;
}

int
drm_syncobj_signal_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file_private)
{
        struct drm_syncobj_array *args = data;
        struct drm_syncobj **syncobjs;
        uint32_t i;
        int ret;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
                return -EOPNOTSUPP;

        if (args->pad != 0)
                return -EINVAL;

        if (args->count_handles == 0)
                return -EINVAL;

        ret = drm_syncobj_array_find(file_private,
                                     u64_to_user_ptr(args->handles),
                                     args->count_handles,
                                     &syncobjs);
        if (ret < 0)
                return ret;

        for (i = 0; i < args->count_handles; i++) {
                ret = drm_syncobj_assign_null_handle(syncobjs[i]);
                if (ret < 0)
                        break;
        }

        drm_syncobj_array_free(syncobjs, args->count_handles);

        return ret;
}

int
drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data,
                                  struct drm_file *file_private)
{
        struct drm_syncobj_timeline_array *args = data;
        struct drm_syncobj **syncobjs;
        struct dma_fence_chain **chains;
        uint64_t *points;
        uint32_t i, j;
        int ret;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
                return -EOPNOTSUPP;

        if (args->flags != 0)
                return -EINVAL;

        if (args->count_handles == 0)
                return -EINVAL;

        ret = drm_syncobj_array_find(file_private,
                                     u64_to_user_ptr(args->handles),
                                     args->count_handles,
                                     &syncobjs);
        if (ret < 0)
                return ret;

        points = kmalloc_array(args->count_handles, sizeof(*points),
                               GFP_KERNEL);
        if (!points) {
                ret = -ENOMEM;
                goto out;
        }
        if (!u64_to_user_ptr(args->points)) {
                memset(points, 0, args->count_handles * sizeof(uint64_t));
        } else if (copy_from_user(points, u64_to_user_ptr(args->points),
                                  sizeof(uint64_t) * args->count_handles)) {
                ret = -EFAULT;
                goto err_points;
        }

        chains = kmalloc_array(args->count_handles, sizeof(void *), GFP_KERNEL);
        if (!chains) {
                ret = -ENOMEM;
                goto err_points;
        }
        for (i = 0; i < args->count_handles; i++) {
                chains[i] = kzalloc(sizeof(struct dma_fence_chain), GFP_KERNEL);
                if (!chains[i]) {
                        for (j = 0; j < i; j++)
                                kfree(chains[j]);
                        ret = -ENOMEM;
                        goto err_chains;
                }
        }

        for (i = 0; i < args->count_handles; i++) {
                struct dma_fence *fence = dma_fence_get_stub();

                drm_syncobj_add_point(syncobjs[i], chains[i],
                                      fence, points[i]);
                dma_fence_put(fence);
        }
err_chains:
        kfree(chains);
err_points:
        kfree(points);
out:
        drm_syncobj_array_free(syncobjs, args->count_handles);

        return ret;
}

int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
                            struct drm_file *file_private)
{
        struct drm_syncobj_timeline_array *args = data;
        struct drm_syncobj **syncobjs;
        uint64_t __user *points = u64_to_user_ptr(args->points);
        uint32_t i;
        int ret;

        if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
                return -EOPNOTSUPP;

        if (args->flags & ~DRM_SYNCOBJ_QUERY_FLAGS_LAST_SUBMITTED)
                return -EINVAL;

        if (args->count_handles == 0)
                return -EINVAL;

        ret = drm_syncobj_array_find(file_private,
                                     u64_to_user_ptr(args->handles),
                                     args->count_handles,
                                     &syncobjs);
        if (ret < 0)
                return ret;

        for (i = 0; i < args->count_handles; i++) {
                struct dma_fence_chain *chain;
                struct dma_fence *fence;
                uint64_t point;

                fence = drm_syncobj_fence_get(syncobjs[i]);
                chain = to_dma_fence_chain(fence);
                if (chain) {
                        struct dma_fence *iter, *last_signaled =
                                dma_fence_get(fence);

                        if (args->flags &
                            DRM_SYNCOBJ_QUERY_FLAGS_LAST_SUBMITTED) {
                                point = fence->seqno;
                        } else {
                                dma_fence_chain_for_each(iter, fence) {
                                        if (iter->context != fence->context) {
                                                dma_fence_put(iter);
                                                /* It is most likely that timeline has
                                                * unorder points. */
                                                break;
                                        }
                                        dma_fence_put(last_signaled);
                                        last_signaled = dma_fence_get(iter);
                                }
                                point = dma_fence_is_signaled(last_signaled) ?
                                        last_signaled->seqno :
                                        to_dma_fence_chain(last_signaled)->prev_seqno;
                        }
                        dma_fence_put(last_signaled);
                } else {
                        point = 0;
                }
                dma_fence_put(fence);
                ret = copy_to_user(&points[i], &point, sizeof(uint64_t));
                ret = ret ? -EFAULT : 0;
                if (ret)
                        break;
        }
        drm_syncobj_array_free(syncobjs, args->count_handles);

        return ret;
}