6.17-stable review patch. If anyone has any objections, please let me know.
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From: Jesse.Zhang Jesse.Zhang@amd.com
[ Upstream commit b8ae2640f9acd4f411c9227d2493755d03fe440a ]
This commit fixes a potential race condition in the userqueue fence signaling mechanism by replacing dma_fence_is_signaled_locked() with dma_fence_is_signaled().
The issue occurred because: 1. dma_fence_is_signaled_locked() should only be used when holding the fence's individual lock, not just the fence list lock 2. Using the locked variant without the proper fence lock could lead to double-signaling scenarios: - Hardware completion signals the fence - Software path also tries to signal the same fence
By using dma_fence_is_signaled() instead, we properly handle the locking hierarchy and avoid the race condition while still maintaining the necessary synchronization through the fence_list_lock.
v2: drop the comment (Christian)
Reviewed-by: Christian König christian.koenig@amd.com Signed-off-by: Jesse Zhang Jesse.Zhang@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c index c2a983ff23c95..b372baae39797 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c @@ -276,7 +276,7 @@ static int amdgpu_userq_fence_create(struct amdgpu_usermode_queue *userq,
/* Check if hardware has already processed the job */ spin_lock_irqsave(&fence_drv->fence_list_lock, flags); - if (!dma_fence_is_signaled_locked(fence)) + if (!dma_fence_is_signaled(fence)) list_add_tail(&userq_fence->link, &fence_drv->fences); else dma_fence_put(fence);