drm/radeon: delete radeon_fence_process in is_signaled, no deadlock

Delete the attempt to progress the queue when checking if fence is
signaled. This avoids deadlock.

dma-fence_ops::signaled can be called with the fence lock in unknown
state. For radeon, the fence lock is also the wait queue lock. This can
cause a self deadlock when signaled() tries to make forward progress on
the wait queue. But advancing the queue is unneeded because incorrectly
returning false from signaled() is perfectly acceptable.

Link: https://github.com/brave/brave-browser/issues/49182
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4641
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Robert McClinton <rbmccav@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 527ba26e50ec2ca2be9c7c82f3ad42998a75d0db)
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/radeon/radeon_fence.c b/drivers/gpu/drm/radeon/radeon_fence.c
index 5b5b54e876d4c29fbcc3c58d82d91d20ebd4231c..167d6f122b8efe13eddd2bd6ae0e322fcbdbf312 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_fence.c
+++ b/drivers/gpu/drm/radeon/radeon_fence.c
@@ -360,13 +360,6 @@ static bool radeon_fence_is_signaled(struct dma_fence *f)
        if (atomic64_read(&rdev->fence_drv[ring].last_seq) >= seq)
                return true;
 
-       if (down_read_trylock(&rdev->exclusive_lock)) {
-               radeon_fence_process(rdev, ring);
-               up_read(&rdev->exclusive_lock);
-
-               if (atomic64_read(&rdev->fence_drv[ring].last_seq) >= seq)
-                       return true;
-       }
        return false;
 }