[PATCH] drm/amdgpu: fix losting fence signal

[Chunming Zhou]

Change-Id: Ibfb7e8af796cc178dfb40d8aaabda472de3c5eda
Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index 17bd5af..6a69336 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -192,9 +192,10 @@ static void amdgpu_fence_schedule_fallback(struct amdgpu_ring *ring)
 void amdgpu_fence_process(struct amdgpu_ring *ring)
 {
 	struct amdgpu_fence_driver *drv = &ring->fence_drv;
-	uint32_t seq, last_seq;
+	uint32_t seq, last_seq, old_seq;
 	int r;
 
+	old_seq = atomic_read(&ring->fence_drv.last_seq);
 	do {
 		last_seq = atomic_read(&ring->fence_drv.last_seq);
 		seq = amdgpu_fence_read(ring);
@@ -204,10 +205,10 @@ void amdgpu_fence_process(struct amdgpu_ring *ring)
 	if (seq != ring->fence_drv.sync_seq)
 		amdgpu_fence_schedule_fallback(ring);
 
-	while (last_seq != seq) {
+	while (old_seq != seq) {
 		struct fence *fence, **ptr;
 
-		ptr = &drv->fences[++last_seq & drv->num_fences_mask];
+		ptr = &drv->fences[++old_seq & drv->num_fences_mask];
 
 		/* There is always exactly one thread signaling this fence slot */
 		fence = rcu_dereference_protected(*ptr, 1);
-- 
1.9.1