[PATCH] dma-buf/reservation: should keep later one in add fence(v2)

[Monk Liu]

v2:
still check context first to avoid warning from dma_fence_is_later
apply this fix in add_shared_replace as well

Change-Id: If6a979ba9fd6c923b82212f35f07a9ff31c86767
Signed-off-by: Monk Liu <Monk.Liu at amd.com>
---
 drivers/dma-buf/reservation.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 314eb10..c6e3c86 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -118,7 +118,8 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
 		old_fence = rcu_dereference_protected(fobj->shared[i],
 						reservation_object_held(obj));
 
-		if (old_fence->context == fence->context) {
+		if (old_fence->context == fence->context &&
+			dma_fence_is_later(fence, old_fence)) {
 			/* memory barrier is added by write_seqcount_begin */
 			RCU_INIT_POINTER(fobj->shared[i], fence);
 			write_seqcount_end(&obj->seq);
@@ -179,7 +180,8 @@ reservation_object_add_shared_replace(struct reservation_object *obj,
 		check = rcu_dereference_protected(old->shared[i],
 						reservation_object_held(obj));
 
-		if (check->context == fence->context ||
+		if ((check->context == fence->context &&
+			dma_fence_is_later(fence, check)) ||
 		    dma_fence_is_signaled(check))
 			RCU_INIT_POINTER(fobj->shared[--k], check);
 		else
-- 
2.7.4