[PATCH 3/4] dma-buf: further relax reservation_object_add_shared_fence

[Christian König]

Other cores don't busy wait any more and we removed the last user of checking
the seqno for changes. Drop updating the number for shared fences altogether.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/dma-buf/reservation.c                    | 6 ------
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 7 +------
 2 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 8fcaddffd5d4..90bc6ef03598 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -237,9 +237,6 @@ void reservation_object_add_shared_fence(struct reservation_object *obj,
 	fobj = reservation_object_get_list(obj);
 	count = fobj->shared_count;
 
-	preempt_disable();
-	write_seqcount_begin(&obj->seq);
-
 	for (i = 0; i < count; ++i) {
 
 		old = rcu_dereference_protected(fobj->shared[i],
@@ -257,9 +254,6 @@ void reservation_object_add_shared_fence(struct reservation_object *obj,
 	RCU_INIT_POINTER(fobj->shared[i], fence);
 	/* pointer update must be visible before we extend the shared_count */
 	smp_store_mb(fobj->shared_count, count);
-
-	write_seqcount_end(&obj->seq);
-	preempt_enable();
 	dma_fence_put(old);
 }
 EXPORT_SYMBOL(reservation_object_add_shared_fence);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index fe062b76ec91..a4640ddc24d1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -251,12 +251,7 @@ static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo,
 	new->shared_max = old->shared_max;
 	new->shared_count = k;
 
-	/* Install the new fence list, seqcount provides the barriers */
-	preempt_disable();
-	write_seqcount_begin(&resv->seq);
-	RCU_INIT_POINTER(resv->fence, new);
-	write_seqcount_end(&resv->seq);
-	preempt_enable();
+	rcu_assign_pointer(resv->fence, new);
 
 	/* Drop the references to the removed fences or move them to ef_list */
 	for (i = j, k = 0; i < old->shared_count; ++i) {
-- 
2.17.1