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>

diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c
index 5954bed606524c2c8daa0004b0a1da071646494a..fbd0f88fc81b044f37ccc6718033b6c6df1332c0 100644 (file)
--- 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))