OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​drm_syncobj.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * 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/dma-fence-unwrap.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) {
             /* If the requested seqno is already signaled
              * drm_syncobj_find_fence may return a NULL
              * fence. To make sure the recipient gets
              * signalled, use a new fence instead.
              */
             if (!*fence)
                 *fence = dma_fence_get_stub();
 
             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 - initializes 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, *tmp;
     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,
                      &tmp);
     if (ret)
         goto err_put_timeline;
 
     fence = dma_fence_unwrap_merge(tmp);
     dma_fence_put(tmp);
     if (!fence) {
         ret = -ENOMEM;
         goto err_put_timeline;
     }
 
     chain = dma_fence_chain_alloc();
     if (!chain) {
         ret = -ENOMEM;
         goto err_free_fence;
     }
 
     drm_syncobj_add_point(timeline_syncobj, chain, fence, args->dst_point);
 err_free_fence:
     dma_fence_put(fence);
 err_put_timeline:
     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] = dma_fence_chain_alloc();
         if (!chains[i]) {
             for (j = 0; j < i; j++)
                 dma_fence_chain_free(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;
 }

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