linux-gen: ring: fix memory ordering in ring dequeue

Acquire ordering is needed to maintain proper release consistency with
the ring enqueue operation. This issue presented itself as deadlock when
running on an ARM-based chip.

Signed-off-by: Brian Brooks <brian.brooks@linaro.org>
Reviewed-by: Bill Fischofer <bill.fischofer@linaro.org>
Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>

platform/linux-generic/include/odp_ring_internal.h

@@ -57,7 +57,7 @@ static inline uint32_t ring_deq(ring_t *ring, uint32_t mask)
 
 	/* Move reader head. This thread owns data at the new head. */
 	do {
-		tail = odp_atomic_load_u32(&ring->w_tail);
+		tail = odp_atomic_load_acq_u32(&ring->w_tail);
 
 		if (head == tail)
 			return RING_EMPTY;
@@ -90,7 +90,7 @@ static inline uint32_t ring_deq_multi(ring_t *ring, uint32_t mask,
 
 	/* Move reader head. This thread owns data at the new head. */
 	do {
-		tail = odp_atomic_load_u32(&ring->w_tail);
+		tail = odp_atomic_load_acq_u32(&ring->w_tail);
 
 		/* Ring is empty */
 		if (head == tail)