[PATCH 03/18] bnx2x: Reduce the likelihood of smb_mb
From: Eilon Greenstein <hidden>
Date: 2009-03-02 18:00:14
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Subject: [PATCH 03/18] 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 <redacted> --- drivers/net/bnx2x_main.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c
index 5954bed..fbd0f88 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))
--
1.5.4.3