[PATCH] drm/amdgpu: add rcu_barrier after entity fini

[Christian König]

Sorry missed that one.

Patch is Reviewed-by: Christian König <christian.koenig at amd.com>.

Nice work,
Christian.

Am 23.05.2018 um 07:25 schrieb Deng, Emily:
> Ping ......
>
>> -----Original Message-----
>> From: Emily Deng [mailto:Emily.Deng at amd.com]
>> Sent: Monday, May 21, 2018 4:09 PM
>> To: amd-gfx at lists.freedesktop.org
>> Cc: Deng, Emily <Emily.Deng at amd.com>
>> Subject: [PATCH] drm/amdgpu: add rcu_barrier after entity fini
>>
>> To free the fence from the amdgpu_fence_slab, need twice call_rcu, to
>> avoid the amdgpu_fence_slab_fini call
>> kmem_cache_destroy(amdgpu_fence_slab) before
>> kmem_cache_free(amdgpu_fence_slab, fence), add rcu_barrier after
>> drm_sched_entity_fini.
>>
>> The kmem_cache_free(amdgpu_fence_slab, fence)'s call trace as below:
>> 1.drm_sched_entity_fini ->
>> drm_sched_entity_cleanup ->
>> dma_fence_put(entity->last_scheduled) ->
>> drm_sched_fence_release_finished ->
>> drm_sched_fence_release_scheduled -> call_rcu(&fence->finished.rcu,
>> drm_sched_fence_free)
>>
>> 2.drm_sched_fence_free ->
>> dma_fence_put(fence->parent) ->
>> amdgpu_fence_release ->
>> call_rcu(&f->rcu, amdgpu_fence_free) ->
>> kmem_cache_free(amdgpu_fence_slab, fence);
>>
>> v2:put the barrier before the kmem_cache_destroy v3:put the
>> dma_fence_put(fence->parent) before call_rcu in
>> drm_sched_fence_release_scheduled
>>
>> Change-Id: I8dcadd3372f97e72461bf46b41cc26d90f09b8df
>> Signed-off-by: Emily Deng <Emily.Deng at amd.com>
>> ---
>>   drivers/gpu/drm/scheduler/sched_fence.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/scheduler/sched_fence.c
>> b/drivers/gpu/drm/scheduler/sched_fence.c
>> index 786b47f..df44616 100644
>> --- a/drivers/gpu/drm/scheduler/sched_fence.c
>> +++ b/drivers/gpu/drm/scheduler/sched_fence.c
>> @@ -98,7 +98,6 @@ static void drm_sched_fence_free(struct rcu_head *rcu)
>>   	struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
>>   	struct drm_sched_fence *fence = to_drm_sched_fence(f);
>>
>> -	dma_fence_put(fence->parent);
>>   	kmem_cache_free(sched_fence_slab, fence);  }
>>
>> @@ -114,6 +113,7 @@ static void
>> drm_sched_fence_release_scheduled(struct dma_fence *f)  {
>>   	struct drm_sched_fence *fence = to_drm_sched_fence(f);
>>
>> +	dma_fence_put(fence->parent);
>>   	call_rcu(&fence->finished.rcu, drm_sched_fence_free);  }
>>
>> --
>> 2.7.4
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