Commit 43cf1fc0 authored by Chunming Zhou's avatar Chunming Zhou Committed by Christian König
Browse files

drm: fix deadlock of syncobj v6 



v2:
add a mutex between sync_cb execution and free.
v3:
clearly separating the roles for pt_lock and cb_mutex (Chris)
v4:
the cb_mutex should be taken outside of the pt_lock around
this if() block. (Chris)
v5:
fix a corner case
v6:
tidy drm_syncobj_fence_get_or_add_callback up. (Chris)

Tested by syncobj_basic and syncobj_wait of igt.

Signed-off-by: default avatarChunming Zhou <david1.zhou@amd.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian König <christian.koenig@amd.com>
Cc: intel-gfx@lists.freedesktop.org
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://patchwork.kernel.org/patch/10652893/
parent 3d42f1dd

drivers/gpu/drm/drm_syncobj.c

+75 −81
Original line number Diff line number Diff line
@@ -106,6 +106,42 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private, 
}

EXPORT_SYMBOL(drm_syncobj_find);



static struct dma_fence

*drm_syncobj_find_signal_pt_for_point(struct drm_syncobj *syncobj,

				      uint64_t point)

{

	struct drm_syncobj_signal_pt *signal_pt;



	if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) &&

	    (point <= syncobj->timeline)) {

		struct drm_syncobj_stub_fence *fence =

			kzalloc(sizeof(struct drm_syncobj_stub_fence),

				GFP_KERNEL);



		if (!fence)

			return NULL;

		spin_lock_init(&fence->lock);

		dma_fence_init(&fence->base,

			       &drm_syncobj_stub_fence_ops,

			       &fence->lock,

			       syncobj->timeline_context,

			       point);



		dma_fence_signal(&fence->base);

		return &fence->base;

	}



	list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) {

		if (point > signal_pt->value)

			continue;

		if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) &&

		    (point != signal_pt->value))

			continue;

		return dma_fence_get(&signal_pt->fence_array->base);

	}

	return NULL;

}



static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj,

					    struct drm_syncobj_cb *cb,

					    drm_syncobj_func_t func)
@@ -114,115 +150,71 @@ static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj, 
	list_add_tail(&cb->node, &syncobj->cb_list);

}



static int drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,

static void drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj,

						  struct dma_fence **fence,

						  struct drm_syncobj_cb *cb,

						  drm_syncobj_func_t func)

{

	int ret;

	u64 pt_value = 0;



	ret = drm_syncobj_search_fence(syncobj, 0, 0, fence);

	if (!ret)

		return 1;

	if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) {

		/*BINARY syncobj always wait on last pt */

		pt_value = syncobj->signal_point;



	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.

	 */

	if (!list_empty(&syncobj->signal_pt_list)) {

		spin_unlock(&syncobj->lock);

		drm_syncobj_search_fence(syncobj, 0, 0, fence);

		if (*fence)

			return 1;

		spin_lock(&syncobj->lock);

	} else {

		*fence = NULL;

		drm_syncobj_add_callback_locked(syncobj, cb, func);

		ret = 0;

		if (pt_value == 0)

			pt_value += DRM_SYNCOBJ_BINARY_POINT;

	}

	spin_unlock(&syncobj->lock);



	return ret;

	mutex_lock(&syncobj->cb_mutex);

	spin_lock(&syncobj->pt_lock);

	*fence = drm_syncobj_find_signal_pt_for_point(syncobj, pt_value);

	spin_unlock(&syncobj->pt_lock);

	if (!*fence)

		drm_syncobj_add_callback_locked(syncobj, cb, func);

	mutex_unlock(&syncobj->cb_mutex);

}



void drm_syncobj_add_callback(struct drm_syncobj *syncobj,

			      struct drm_syncobj_cb *cb,

			      drm_syncobj_func_t func)

{

	spin_lock(&syncobj->lock);

	mutex_lock(&syncobj->cb_mutex);

	drm_syncobj_add_callback_locked(syncobj, cb, func);

	spin_unlock(&syncobj->lock);

	mutex_unlock(&syncobj->cb_mutex);

}



void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,

				 struct drm_syncobj_cb *cb)

{

	spin_lock(&syncobj->lock);

	mutex_lock(&syncobj->cb_mutex);

	list_del_init(&cb->node);

	spin_unlock(&syncobj->lock);

	mutex_unlock(&syncobj->cb_mutex);

}



static void drm_syncobj_init(struct drm_syncobj *syncobj)

{

	spin_lock(&syncobj->lock);

	spin_lock(&syncobj->pt_lock);

	syncobj->timeline_context = dma_fence_context_alloc(1);

	syncobj->timeline = 0;

	syncobj->signal_point = 0;

	init_waitqueue_head(&syncobj->wq);



	INIT_LIST_HEAD(&syncobj->signal_pt_list);

	spin_unlock(&syncobj->lock);

	spin_unlock(&syncobj->pt_lock);

}



static void drm_syncobj_fini(struct drm_syncobj *syncobj)

{

	struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;



	spin_lock(&syncobj->lock);

	spin_lock(&syncobj->pt_lock);

	list_for_each_entry_safe(signal_pt, tmp,

				 &syncobj->signal_pt_list, list) {

		list_del(&signal_pt->list);

		dma_fence_put(&signal_pt->fence_array->base);

		kfree(signal_pt);

	}

	spin_unlock(&syncobj->lock);

}



static struct dma_fence

*drm_syncobj_find_signal_pt_for_point(struct drm_syncobj *syncobj,

				      uint64_t point)

{

	struct drm_syncobj_signal_pt *signal_pt;



	if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) &&

	    (point <= syncobj->timeline)) {

		struct drm_syncobj_stub_fence *fence =

			kzalloc(sizeof(struct drm_syncobj_stub_fence),

				GFP_KERNEL);



		if (!fence)

			return NULL;

		spin_lock_init(&fence->lock);

		dma_fence_init(&fence->base,

			       &drm_syncobj_stub_fence_ops,

			       &fence->lock,

			       syncobj->timeline_context,

			       point);



		dma_fence_signal(&fence->base);

		return &fence->base;

	}



	list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) {

		if (point > signal_pt->value)

			continue;

		if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) &&

		    (point != signal_pt->value))

			continue;

		return dma_fence_get(&signal_pt->fence_array->base);

	}

	return NULL;

	spin_unlock(&syncobj->pt_lock);

}



static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj,
@@ -249,14 +241,14 @@ static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj, 
	fences[num_fences++] = dma_fence_get(fence);

	/* timeline syncobj must take this dependency */

	if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {

		spin_lock(&syncobj->lock);

		spin_lock(&syncobj->pt_lock);

		if (!list_empty(&syncobj->signal_pt_list)) {

			tail_pt = list_last_entry(&syncobj->signal_pt_list,

						  struct drm_syncobj_signal_pt, list);

			fences[num_fences++] =

				dma_fence_get(&tail_pt->fence_array->base);

		}

		spin_unlock(&syncobj->lock);

		spin_unlock(&syncobj->pt_lock);

	}

	signal_pt->fence_array = dma_fence_array_create(num_fences, fences,

							syncobj->timeline_context,
@@ -266,16 +258,16 @@ static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj, 
		goto fail;

	}



	spin_lock(&syncobj->lock);

	spin_lock(&syncobj->pt_lock);

	if (syncobj->signal_point >= point) {

		DRM_WARN("A later signal is ready!");

		spin_unlock(&syncobj->lock);

		spin_unlock(&syncobj->pt_lock);

		goto exist;

	}

	signal_pt->value = point;

	list_add_tail(&signal_pt->list, &syncobj->signal_pt_list);

	syncobj->signal_point = point;

	spin_unlock(&syncobj->lock);

	spin_unlock(&syncobj->pt_lock);

	wake_up_all(&syncobj->wq);



	return 0;
@@ -294,7 +286,7 @@ static void drm_syncobj_garbage_collection(struct drm_syncobj *syncobj) 
{

	struct drm_syncobj_signal_pt *signal_pt, *tmp, *tail_pt;



	spin_lock(&syncobj->lock);

	spin_lock(&syncobj->pt_lock);

	tail_pt = list_last_entry(&syncobj->signal_pt_list,

				  struct drm_syncobj_signal_pt,

				  list);
@@ -315,7 +307,7 @@ static void drm_syncobj_garbage_collection(struct drm_syncobj *syncobj) 
		}

	}



	spin_unlock(&syncobj->lock);

	spin_unlock(&syncobj->pt_lock);

}

/**

 * drm_syncobj_replace_fence - replace fence in a sync object.
@@ -344,13 +336,14 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj, 
	drm_syncobj_create_signal_pt(syncobj, fence, pt_value);

	if (fence) {

		struct drm_syncobj_cb *cur, *tmp;

		LIST_HEAD(cb_list);



		spin_lock(&syncobj->lock);

		mutex_lock(&syncobj->cb_mutex);

		list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) {

			list_del_init(&cur->node);

			cur->func(syncobj, cur);

		}

		spin_unlock(&syncobj->lock);

		mutex_unlock(&syncobj->cb_mutex);

	}

}

EXPORT_SYMBOL(drm_syncobj_replace_fence);
@@ -386,11 +379,11 @@ drm_syncobj_point_get(struct drm_syncobj *syncobj, u64 point, u64 flags, 
		if (ret < 0)

			return ret;

	}

	spin_lock(&syncobj->lock);

	spin_lock(&syncobj->pt_lock);

	*fence = drm_syncobj_find_signal_pt_for_point(syncobj, point);

	if (!*fence)

		ret = -EINVAL;

	spin_unlock(&syncobj->lock);

	spin_unlock(&syncobj->pt_lock);

	return ret;

}
@@ -500,7 +493,8 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags, 


	kref_init(&syncobj->refcount);

	INIT_LIST_HEAD(&syncobj->cb_list);

	spin_lock_init(&syncobj->lock);

	spin_lock_init(&syncobj->pt_lock);

	mutex_init(&syncobj->cb_mutex);

	if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE)

		syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;

	else

include/drm/drm_syncobj.h

+6 −2
Original line number Diff line number Diff line
@@ -75,9 +75,13 @@ struct drm_syncobj { 
         */

	struct list_head cb_list;

	/**

	 * @lock: Protects syncobj list and write-locks &fence.

	 * @pt_lock: Protects pt list.

	 */

	spinlock_t lock;

	spinlock_t pt_lock;

	/**

	 * @cb_mutex: Protects syncobj cb list.

	 */

	struct mutex cb_mutex;

	/**

	 * @file: A file backing for this syncobj.

	 */

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