| From ab3f718f95dd63e96c1f85de373985487e6c4a88 Mon Sep 17 00:00:00 2001 |
| From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com> |
| Date: Fri, 29 Mar 2019 19:30:23 +0100 |
| Subject: drm/amdgpu: fix old fence check in amdgpu_fence_emit |
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| Content-Type: text/plain; charset=UTF-8 |
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| |
| [ 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@amd.com> |
| Reviewed-by: Chunming Zhou <david1.zhou@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_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 ee47c11e92ce7..4dee2326b29c3 100644 |
| --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c |
| +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c |
| @@ -136,8 +136,9 @@ 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) |
| @@ -153,15 +154,24 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct dma_fence **f, |
| seq, flags | 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 |
| |