mm-drivers: hw_fence: Fix join fence signaling

It is possible that one (or more) child fences get signaled by
fence controller, right after we add the join fence as parent
fence of the child fence. If so, the join fence pending child
count may become 0 which means we can safely signal the join
fence.

Change-Id: I0222b93a62db13eeb7867f3741c1db944df036b1
Signed-off-by: Harshdeep Dhatt <quic_hdhatt@quicinc.com>

hw_fence/src/hw_fence_drv_priv.c

@@ -1124,7 +1124,7 @@ int hw_fence_process_fence_array(struct hw_fence_driver_data *drv_data,
 	struct msm_hw_fence *join_fence;
 	struct msm_hw_fence *hw_fence_child;
 	struct dma_fence *child_fence;
-	u32 signaled_fences = 0;
+	bool signal_join_fence = false;
 	u64 hash_join_fence, hash;
 	int i, ret = 0;
 
@@ -1178,13 +1178,13 @@ int hw_fence_process_fence_array(struct hw_fence_driver_data *drv_data,
 
 			/* child fence is already signaled */
 			GLOBAL_ATOMIC_STORE(&join_fence->lock, 1); /* lock */
-			join_fence->pending_child_cnt--;
+			if (--join_fence->pending_child_cnt == 0)
+				signal_join_fence = true;
 
 			/* update memory for the table update */
 			wmb();
 
 			GLOBAL_ATOMIC_STORE(&join_fence->lock, 0); /* unlock */
-			signaled_fences++;
 		} else {
 
 			/* child fence is not signaled */
@@ -1216,7 +1216,7 @@ int hw_fence_process_fence_array(struct hw_fence_driver_data *drv_data,
 	}
 
 	/* all fences were signaled, signal client now */
-	if (signaled_fences == array->num_fences) {
+	if (signal_join_fence) {
 
 		/* signal the join hw fence */
 		_fence_ctl_signal(drv_data, hw_fence_client, join_fence, hash_join_fence, 0, 0);