For S2M rings, ring->head is updated by the sender and eth_memif_tx
function is called in the context of sending thread. The loads in
the sender do not need to synchronize with its own stores.
Fixes: a2aafb9aa651 ("net/memif: optimize with one-way barrier")
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Honnappa Nagarahalli <[email protected]>
Reviewed-by: Phil Yang <[email protected]>
Reviewed-by: Ruifeng Wang <[email protected]>
---
drivers/net/memif/rte_eth_memif.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/net/memif/rte_eth_memif.c
b/drivers/net/memif/rte_eth_memif.c
index 159b45180..96db76121 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -585,7 +585,13 @@ eth_memif_tx(void *queue, struct rte_mbuf **bufs, uint16_t
nb_pkts)
mask = ring_size - 1;
if (type == MEMIF_RING_S2M) {
- slot = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE);
+ /* For S2M queues ring->head is updated by the sender and
+ * this function is called in the context of sending thread.
+ * The loads in the sender do not need to synchronize with
+ * its own stores. Hence, the following load can be a
+ * relaxed load.
+ */
+ slot = __atomic_load_n(&ring->head, __ATOMIC_RELAXED);
n_free = ring_size - slot +
__atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
} else {
--
2.17.1
