pci/drm/drm_syncobj.c

32  * DRM synchronisation objects (syncobj, see struct &drm_syncobj) provide a
37  * The syncobj userspace API provides ioctls for several operations:
40  *  - Import and export of syncobjs to/from a syncobj file descriptor
41  *  - Import and export a syncobj's underlying fence to/from a sync file
42  *  - Reset a syncobj (set its fence to NULL)
43  *  - Signal a syncobj (set a trivially signaled fence)
44  *  - Wait for a syncobj's fence to appear and be signaled
46  * The syncobj userspace API also provides operations to manipulate a syncobj
54  * At it's core, a syncobj is simply a wrapper around a pointer to a struct
56  * When a syncobj is first created, its pointer is either NULL or a pointer
61  * If the syncobj is considered as a binary (its state is either signaled or
63  * the syncobj, the syncobj's fence is replaced with a fence which will be
65  * If the syncobj is considered as a timeline primitive, when GPU work is
66  * enqueued in a DRM driver to signal the a given point of the syncobj, a new
68  * pointing to the previous fence that was in the syncobj. The new struct
69  * &dma_fence_chain fence replace the syncobj's fence and will be signaled by
71  * fence previously in the syncobj.
73  * When GPU work which waits on a syncobj is enqueued in a DRM driver, at the
74  * time the work is enqueued, it waits on the syncobj's fence before
77  *    - The syncobj's current fence if the syncobj is considered as a binary
79  *    - The struct &dma_fence associated with a given point if the syncobj is
82  * If the syncobj's fence is NULL or not present in the syncobj's timeline,
85  * With binary syncobj, all manipulation of the syncobjs's fence happens in
90  * to manipulate a syncobj from the host by resetting its pointer to NULL or
93  * With a timeline syncobj, all manipulation of the synobj's fence happens in
99  * ioctl() when dealing with syncobj considered as timeline. Using a binary
100  * set of ioctl() with a syncobj considered as timeline could result incorrect
101  * synchronization. The use of binary syncobj is supported through the
104  * syncobj's fence when signaling).
110  * &DRM_IOCTL_SYNCOBJ_WAIT takes an array of syncobj handles and does a
111  * host-side wait on all of the syncobj fences simultaneously.
113  * all of the syncobj fences to be signaled before it returns.
114  * Otherwise, it returns once at least one syncobj fence has been signaled
118  * fence in a syncobj, if &DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT is set,
119  * the host-side wait will first wait for the syncobj to receive a non-NULL
123  * Assuming the syncobj starts off with a NULL fence, this allows a client
129  * Similarly, &DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT takes an array of syncobj
131  * of syncobj fences at the given points simultaneously.
140  * blocking: an eventfd will be signaled when the syncobj is. This is useful to
150  * The first lets the client import or export an entire syncobj to a file
153  * syncobj between processes.
154  * All exported file descriptors and any syncobj handles created as a
156  * same underlying struct &drm_syncobj and the syncobj can be used
158  * The syncobj is freed only once the last reference is dropped.
159  * Unlike dma-buf, importing a syncobj creates a new handle (with its own
167  * import/export the syncobj's current fence from/to a &sync_file.
168  * When a syncobj is exported to a sync file, that sync file wraps the
170  * operations on the syncobj will not affect the exported sync file.
171  * When a sync file is imported into a syncobj, the syncobj's fence is set
173  * Because sync files are immutable, resetting or signaling the syncobj
175  * syncobj.
182  * &dma_fence_chain of a syncobj at a given u64 point to another u64 point
183  * into another syncobj.
186  * point on a timeline syncobj from/into a binary syncobj, you can use the
187  * point 0 to mean take/replace the fence in the syncobj.
221 static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
228 	struct drm_syncobj *syncobj;
235 syncobj_eventfd_entry_func(struct drm_syncobj *syncobj,
243  * Returns a reference to the syncobj pointed to by handle or NULL. The
249 	struct drm_syncobj *syncobj;
254 	syncobj = idr_find(&file_private->syncobj_idr, handle);
255 	if (syncobj)
256 		drm_syncobj_get(syncobj);
260 	return syncobj;
264 static void drm_syncobj_fence_add_wait(struct drm_syncobj *syncobj,
272 	spin_lock(&syncobj->lock);
277 	fence = dma_fence_get(rcu_dereference_protected(syncobj->fence, 1));
280 		list_add_tail(&wait->node, &syncobj->cb_list);
286 	spin_unlock(&syncobj->lock);
289 static void drm_syncobj_remove_wait(struct drm_syncobj *syncobj,
295 	spin_lock(&syncobj->lock);
297 	spin_unlock(&syncobj->lock);
305 	/* This happens either inside the syncobj lock, or after the node has
314 drm_syncobj_add_eventfd(struct drm_syncobj *syncobj,
317 	spin_lock(&syncobj->lock);
318 	list_add_tail(&entry->node, &syncobj->ev_fd_list);
319 	syncobj_eventfd_entry_func(syncobj, entry);
320 	spin_unlock(&syncobj->lock);
325  * drm_syncobj_add_point - add new timeline point to the syncobj
326  * @syncobj: sync object to add timeline point do
331  * Add the chain node as new timeline point to the syncobj.
333 void drm_syncobj_add_point(struct drm_syncobj *syncobj,
344 	spin_lock(&syncobj->lock);
346 	prev = drm_syncobj_fence_get(syncobj);
351 	rcu_assign_pointer(syncobj->fence, &chain->base);
353 	list_for_each_entry_safe(wait_cur, wait_tmp, &syncobj->cb_list, node)
354 		syncobj_wait_syncobj_func(syncobj, wait_cur);
355 	list_for_each_entry_safe(ev_fd_cur, ev_fd_tmp, &syncobj->ev_fd_list, node)
356 		syncobj_eventfd_entry_func(syncobj, ev_fd_cur);
357 	spin_unlock(&syncobj->lock);
367  * @syncobj: Sync object to replace fence in
372 void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
382 	spin_lock(&syncobj->lock);
384 	old_fence = rcu_dereference_protected(syncobj->fence,
385 					      lockdep_is_held(&syncobj->lock));
386 	rcu_assign_pointer(syncobj->fence, fence);
389 		list_for_each_entry_safe(wait_cur, wait_tmp, &syncobj->cb_list, node)
390 			syncobj_wait_syncobj_func(syncobj, wait_cur);
391 		list_for_each_entry_safe(ev_fd_cur, ev_fd_tmp, &syncobj->ev_fd_list, node)
392 			syncobj_eventfd_entry_func(syncobj, ev_fd_cur);
395 	spin_unlock(&syncobj->lock);
403  * @syncobj: sync object to assign the fence on
407 static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
414 	drm_syncobj_replace_fence(syncobj, fence);
440 	struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
445 	if (!syncobj)
457 	*fence = drm_syncobj_fence_get(syncobj);
487 	drm_syncobj_fence_add_wait(syncobj, &wait);
512 		drm_syncobj_remove_wait(syncobj, &wait);
515 	drm_syncobj_put(syncobj);
529 	struct drm_syncobj *syncobj = container_of(kref,
534 	drm_syncobj_replace_fence(syncobj, NULL);
536 	list_for_each_entry_safe(ev_fd_cur, ev_fd_tmp, &syncobj->ev_fd_list, node)
539 	kfree(syncobj);
544  * drm_syncobj_create - create a new syncobj
545  * @out_syncobj: returned syncobj
547  * @fence: if non-NULL, the syncobj will represent this fence
559 	struct drm_syncobj *syncobj;
561 	syncobj = kzalloc(sizeof(struct drm_syncobj), GFP_KERNEL);
562 	if (!syncobj)
565 	kref_init(&syncobj->refcount);
566 	INIT_LIST_HEAD(&syncobj->cb_list);
567 	INIT_LIST_HEAD(&syncobj->ev_fd_list);
568 	mtx_init(&syncobj->lock, IPL_NONE);
571 		ret = drm_syncobj_assign_null_handle(syncobj);
573 			drm_syncobj_put(syncobj);
579 		drm_syncobj_replace_fence(syncobj, fence);
581 	*out_syncobj = syncobj;
587  * drm_syncobj_get_handle - get a handle from a syncobj
589  * @syncobj: Sync object to export
598 			   struct drm_syncobj *syncobj, u32 *handle)
603 	drm_syncobj_get(syncobj);
607 	ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
613 		drm_syncobj_put(syncobj);
626 	struct drm_syncobj *syncobj;
628 	ret = drm_syncobj_create(&syncobj, flags, NULL);
632 	ret = drm_syncobj_get_handle(file_private, syncobj, handle);
633 	drm_syncobj_put(syncobj);
640 	struct drm_syncobj *syncobj;
643 	syncobj = idr_remove(&file_private->syncobj_idr, handle);
646 	if (!syncobj)
649 	drm_syncobj_put(syncobj);
656 	struct drm_syncobj *syncobj = file->private_data;
658 	drm_syncobj_put(syncobj);
668  * drm_syncobj_get_fd - get a file descriptor from a syncobj
669  * @syncobj: Sync object to export
676 int drm_syncobj_get_fd(struct drm_syncobj *syncobj, int *p_fd)
690 				  syncobj, 0);
696 	drm_syncobj_get(syncobj);
708 	struct drm_syncobj *syncobj = drm_syncobj_find(file_private, handle);
711 	if (!syncobj)
714 	ret = drm_syncobj_get_fd(syncobj, p_fd);
715 	drm_syncobj_put(syncobj);
725 	struct drm_syncobj *syncobj;
738 	syncobj = f.file->private_data;
739 	drm_syncobj_get(syncobj);
743 	ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
751 		drm_syncobj_put(syncobj);
762 	struct drm_syncobj *syncobj;
767 	syncobj = drm_syncobj_find(file_private, handle);
768 	if (!syncobj) {
773 	drm_syncobj_replace_fence(syncobj, fence);
775 	drm_syncobj_put(syncobj);
812  * drm_syncobj_open - initializes syncobj file-private structures at devnode open time
828 	struct drm_syncobj *syncobj = ptr;
830 	drm_syncobj_put(syncobj);
1065 static void syncobj_wait_syncobj_func(struct drm_syncobj *syncobj,
1070 	/* This happens inside the syncobj lock */
1071 	fence = rcu_dereference_protected(syncobj->fence,
1072 					  lockdep_is_held(&syncobj->lock));
1123 	 * a syncobj with a missing fence and then never have the chance of
1441 syncobj_eventfd_entry_func(struct drm_syncobj *syncobj,
1447 	/* This happens inside the syncobj lock */
1448 	fence = dma_fence_get(rcu_dereference_protected(syncobj->fence, 1));
1489 	struct drm_syncobj *syncobj;
1502 	syncobj = drm_syncobj_find(file_private, args->handle);
1503 	if (!syncobj)
1515 	entry->syncobj = syncobj;
1520 	drm_syncobj_add_eventfd(syncobj, entry);
1521 	drm_syncobj_put(syncobj);