Commit fd921693 authored by David Stevens's avatar David Stevens Committed by Christian König
Browse files

drm/syncobj: use newly allocated stub fences 



Allocate a new private stub fence in drm_syncobj_assign_null_handle,
instead of using a static stub fence.

When userspace creates a fence with DRM_SYNCOBJ_CREATE_SIGNALED or when
userspace signals a fence via DRM_IOCTL_SYNCOBJ_SIGNAL, the timestamp
obtained when the fence is exported and queried with SYNC_IOC_FILE_INFO
should match when the fence's status was changed from the perspective of
userspace, which is during the respective ioctl.

When a static stub fence started being used in by these ioctls, this
behavior changed. Instead, the timestamp returned by SYNC_IOC_FILE_INFO
became the first time anything used the static stub fence, which has no
meaning to userspace.

Signed-off-by: default avatarDavid Stevens <stevensd@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210408095428.3983055-1-stevensd@google.com


Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
parent 7513ce49

drivers/dma-buf/dma-fence.c

+26 −1
Original line number Diff line number Diff line
@@ -123,7 +123,9 @@ static const struct dma_fence_ops dma_fence_stub_ops = { 
/**

 * dma_fence_get_stub - return a signaled fence

 *

 * Return a stub fence which is already signaled.

 * Return a stub fence which is already signaled. The fence's

 * timestamp corresponds to the first time after boot this

 * function is called.

 */

struct dma_fence *dma_fence_get_stub(void)

{
@@ -141,6 +143,29 @@ struct dma_fence *dma_fence_get_stub(void) 
}

EXPORT_SYMBOL(dma_fence_get_stub);



/**

 * dma_fence_allocate_private_stub - return a private, signaled fence

 *

 * Return a newly allocated and signaled stub fence.

 */

struct dma_fence *dma_fence_allocate_private_stub(void)

{

	struct dma_fence *fence;



	fence = kzalloc(sizeof(*fence), GFP_KERNEL);

	if (fence == NULL)

		return ERR_PTR(-ENOMEM);



	dma_fence_init(fence,

		       &dma_fence_stub_ops,

		       &dma_fence_stub_lock,

		       0, 0);

	dma_fence_signal(fence);



	return fence;

}

EXPORT_SYMBOL(dma_fence_allocate_private_stub);



/**

 * dma_fence_context_alloc - allocate an array of fence contexts

 * @num: amount of contexts to allocate

drivers/gpu/drm/drm_syncobj.c

+19 −6
Original line number Diff line number Diff line
@@ -350,12 +350,16 @@ EXPORT_SYMBOL(drm_syncobj_replace_fence); 
 *

 * Assign a already signaled stub fence to the sync object.

 */

static void drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)

static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)

{

	struct dma_fence *fence = dma_fence_get_stub();

	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 */
@@ -478,6 +482,7 @@ EXPORT_SYMBOL(drm_syncobj_free); 
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);
@@ -488,8 +493,13 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags, 
	INIT_LIST_HEAD(&syncobj->cb_list);

	spin_lock_init(&syncobj->lock);



	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED)

		drm_syncobj_assign_null_handle(syncobj);

	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);
@@ -1334,8 +1344,11 @@ drm_syncobj_signal_ioctl(struct drm_device *dev, void *data, 
	if (ret < 0)

		return ret;



	for (i = 0; i < args->count_handles; i++)

		drm_syncobj_assign_null_handle(syncobjs[i]);

	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);

include/linux/dma-fence.h

+1 −0
Original line number Diff line number Diff line
@@ -587,6 +587,7 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr) 
}



struct dma_fence *dma_fence_get_stub(void);

struct dma_fence *dma_fence_allocate_private_stub(void);

u64 dma_fence_context_alloc(unsigned num);



#define DMA_FENCE_TRACE(f, fmt, args...) \