bnx2x: Reduce the likelihood of smb_mb

As the comment explains, this smb_mb is needed only if the queue is stopped
(which is unlikely) so the barrier can be moved to that location

Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c
index 5954bed60652..fbd0f88fc81b 100644
--- a/drivers/net/bnx2x_main.c
+++ b/drivers/net/bnx2x_main.c
@@ -916,18 +916,19 @@ static void bnx2x_tx_int(struct bnx2x_fastpath *fp, int work)
         fp->tx_pkt_cons = sw_cons;
         fp->tx_bd_cons = bd_cons;
 
-        /* Need to make the tx_bd_cons update visible to start_xmit()
-         * before checking for netif_tx_queue_stopped().  Without the
-         * memory barrier, there is a small possibility that start_xmit()
-         * will miss it and cause the queue to be stopped forever.
-         */
-        smp_mb();
-
         /* TBD need a thresh? */
         if (unlikely(netif_tx_queue_stopped(txq))) {
 
                 __netif_tx_lock(txq, smp_processor_id());
 
+                /* Need to make the tx_bd_cons update visible to start_xmit()
+                 * before checking for netif_tx_queue_stopped().  Without the
+                 * memory barrier, there is a small possibility that
+                 * start_xmit() will miss it and cause the queue to be stopped
+                 * forever.
+                 */
+                smp_mb();
+
                 if ((netif_tx_queue_stopped(txq)) &&
                     (bp->state == BNX2X_STATE_OPEN) &&
                     (bnx2x_tx_avail(fp) >= MAX_SKB_FRAGS + 3))