net: netdev_tx_sent_queue() small optimization

Change smp_mb() imediately following a set_bit()
with smp_mb__after_atomic().

Signed-off-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: edumazet

include/linux/netdevice.h

@@ -3517,7 +3517,7 @@ static inline void netdev_tx_sent_queue(struct netdev_queue *dev_queue,
 	 * because in netdev_tx_completed_queue we update the dql_completed
 	 * before checking the XOFF flag.
 	 */
-	smp_mb();
+	smp_mb__after_atomic();
 
 	/* check again in case another CPU has just made room avail */
 	if (unlikely(dql_avail(&dev_queue->dql) >= 0))