NAK, we have tried this before. This way we can accidentally try to signal a fence twice when the fence value is somehow corrupted. Christian. Am 25.10.2017 um 11:22 schrieb Monk Liu: > In amdgpu_fence_process it shouldn't put the signaled hw fence and set > RCU pointer to NULL, instead the more reasonable sequence is just leave > the RCU be there untouched, and: > 1) Either driver_fini() should put this RCU fence or > 2) New hw fence emitting should take the RCU slot and put the old hw fence. > > mapping between get & put on hw fence is: > > Get Put > fence_emit:fence_init ---> free_job:put job->fence > ---> run_job:put job->fence //GPU RESET case > > fence_emit:rcu_assign_pointer ---> fence_driver_fini:put ring->fence_drv.fences[j] > ---> fence_emit:put(old) //after fence_wait(old) > > run_job:job->fence=fence_get() --> sched_main:put(fence) > --> job_recovery:put(fence) //for GPU RESET case > > sched_main:parent=fence_get() --> sched_fence_free:put(fence->parent) > sched_job_recovery:parent=fence_get() --> sched_hw_job_reset:put(s_job->s_fence->parent) // for GPU RESET case > > Change-Id: I623167c1e3143233f4e1be7a400a9b698b4a1355 > Signed-off-by: Monk Liu <Monk.Liu at amd.com> > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c > index f43319c..d7374cf 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c > @@ -161,6 +161,8 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct dma_fence **f) > dma_fence_wait(old, false); > } > > + dma_fence_put(old); > + > rcu_assign_pointer(*ptr, dma_fence_get(&fence->base)); > > *f = &fence->base; > @@ -246,7 +248,6 @@ void amdgpu_fence_process(struct amdgpu_ring *ring) > > /* There is always exactly one thread signaling this fence slot */ > fence = rcu_dereference_protected(*ptr, 1); > - RCU_INIT_POINTER(*ptr, NULL); > > if (!fence) > continue; > @@ -257,7 +258,6 @@ void amdgpu_fence_process(struct amdgpu_ring *ring) > else > BUG(); > > - dma_fence_put(fence); > } while (last_seq != seq); > } >
