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bnx2x: Reduce the likelihood of smb_mb

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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>
This commit is contained in:
Eilon Greenstein 2009-03-02 07:59:24 +00:00 committed by David S. Miller
parent 0d1a8d2d7d
commit 6044735d8d
1 changed files with 8 additions and 7 deletions
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15
drivers/net/bnx2x_main.c
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@ -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))