Am 07.12.21 um 02:32 schrieb Bas Nieuwenhuizen:
See the comments in the code. Basically if the seqno is already signalled then we get a NULL fence. If we then put the NULL fence in a binary syncobj it counts as unsignalled, making that syncobj pretty much useless for all expected uses.
Not 100% sure about the transfer to a timeline syncobj but I believe it is needed there too, as AFAICT the add_point function assumes the fence isn't NULL.
Fixes: ea569910cbab ("drm/syncobj: add transition iotcls between binary and timeline v2") Cc: stable@vger.kernel.org Signed-off-by: Bas Nieuwenhuizen bas@basnieuwenhuizen.nl
Reviewed-by: Christian König christian.koenig@amd.com
Going to push that to drm-misc-fixes later today if nobody objects in the meantime.
drivers/gpu/drm/drm_syncobj.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index fdd2ec87cdd1..eb28a40400d2 100644 --- a/drivers/gpu/drm/drm_syncobj.c +++ b/drivers/gpu/drm/drm_syncobj.c @@ -861,6 +861,19 @@ static int drm_syncobj_transfer_to_timeline(struct drm_file *file_private, &fence); if (ret) goto err;
- /* 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_allocate_private_stub();if (!fence) {ret = -ENOMEM;goto err;}- }
- chain = kzalloc(sizeof(struct dma_fence_chain), GFP_KERNEL); if (!chain) { ret = -ENOMEM;
@@ -890,6 +903,19 @@ drm_syncobj_transfer_to_binary(struct drm_file *file_private, args->src_point, args->flags, &fence); if (ret) goto err;
- /* 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_allocate_private_stub();if (!fence) {ret = -ENOMEM;goto err;}- }
- drm_syncobj_replace_fence(binary_syncobj, fence); dma_fence_put(fence); err: