[ Upstream commit 3d2aca8c8620346abdba96c6300d2c0b90a1d0cc ]
We don't hold a reference to the old fence, so it can go away
any time we are waiting for it to signal.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Reviewed-by: Chunming Zhou <david1.zhou@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 24 ++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
index 333bad7490678..415e9a384799e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
@@ -135,8 +135,9 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct dma_fence **f)
{
struct amdgpu_device *adev = ring->adev;
struct amdgpu_fence *fence;
- struct dma_fence *old, **ptr;
+ struct dma_fence __rcu **ptr;
uint32_t seq;
+ int r;
fence = kmem_cache_alloc(amdgpu_fence_slab, GFP_KERNEL);
if (fence == NULL)
@@ -152,15 +153,24 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct dma_fence **f)
seq, AMDGPU_FENCE_FLAG_INT);
ptr = &ring->fence_drv.fences[seq & ring->fence_drv.num_fences_mask];
+ if (unlikely(rcu_dereference_protected(*ptr, 1))) {
+ struct dma_fence *old;
+
+ rcu_read_lock();
+ old = dma_fence_get_rcu_safe(ptr);
+ rcu_read_unlock();
+
+ if (old) {
+ r = dma_fence_wait(old, false);
+ dma_fence_put(old);
+ if (r)
+ return r;
+ }
+ }
+
/* This function can't be called concurrently anyway, otherwise
* emitting the fence would mess up the hardware ring buffer.
*/
- old = rcu_dereference_protected(*ptr, 1);
- if (old && !dma_fence_is_signaled(old)) {
- DRM_INFO("rcu slot is busy\n");
- dma_fence_wait(old, false);
- }
-
rcu_assign_pointer(*ptr, dma_fence_get(&fence->base));
*f = &fence->base;
--
2.20.1
