From 2d99cf16f42b1979a2c498bb6d09498dbd689978 Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Tue, 9 Mar 2010 06:55:00 +0000 Subject: bnx2x: use smp_mb() to keep ordering of read write operations Since we want to keep ordering of write to fp->bd_tx_cons and netif_tx_queue_stopped(txq), what is read of txq->state, we have to use general memory barrier. Signed-off-by: Stanislaw Gruszka Signed-off-by: David S. Miller --- drivers/net/bnx2x_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/net/bnx2x_main.c') diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c index ed785a30e98b..9fc0f6a7a5e9 100644 --- a/drivers/net/bnx2x_main.c +++ b/drivers/net/bnx2x_main.c @@ -963,7 +963,7 @@ static int bnx2x_tx_int(struct bnx2x_fastpath *fp) * start_xmit() will miss it and cause the queue to be stopped * forever. */ - smp_wmb(); + smp_mb(); /* TBD need a thresh? */ if (unlikely(netif_tx_queue_stopped(txq))) { -- cgit v1.2.3 From 0efc22f3afa5d8f070a33fea06162d7d9d518e38 Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Tue, 9 Mar 2010 06:55:01 +0000 Subject: bnx2x: remove not necessary compiler barrier Access to fp->tx_bd_prod is protected by __netif_tx_lock, so we do not need any barrier for that. Update of fp->tx_bd_cons in bnx2x_tx_int() is not protected by lock, but barrier() nor smb_mb() in bnx2x_tx_avail() not guarantee we will see values that is written on other cpu. Ordering issues between netif_tx_stop_queue(), netif_tx_queue_stopped(), fp->tx_bd_cons = bd_cons and bnx2x_tx_avail() are already handled by smp_mb() in bnx2x_tx_int() and bnx2x_start_xmit(). Signed-off-by: Stanislaw Gruszka Signed-off-by: Eilon Greenstein Signed-off-by: David S. Miller --- drivers/net/bnx2x_main.c | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/net/bnx2x_main.c') diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c index 9fc0f6a7a5e9..ae62b67aa597 100644 --- a/drivers/net/bnx2x_main.c +++ b/drivers/net/bnx2x_main.c @@ -893,7 +893,6 @@ static inline u16 bnx2x_tx_avail(struct bnx2x_fastpath *fp) u16 prod; u16 cons; - barrier(); /* Tell compiler that prod and cons can change */ prod = fp->tx_bd_prod; cons = fp->tx_bd_cons; -- cgit v1.2.3 From 9baddeb8c6c7faa7da8706ad629f09ca221850c1 Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Tue, 9 Mar 2010 06:55:02 +0000 Subject: bnx2x: change smp_mb() comment to conform the true Access to fp->tx_bp_prod is protected by __netif_tx_lock, smp_mb() is not needed for that. Signed-off-by: Stanislaw Gruszka Signed-off-by: Eilon Greenstein Signed-off-by: David S. Miller --- drivers/net/bnx2x_main.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers/net/bnx2x_main.c') diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c index ae62b67aa597..6c042a72d6cc 100644 --- a/drivers/net/bnx2x_main.c +++ b/drivers/net/bnx2x_main.c @@ -11428,9 +11428,12 @@ static netdev_tx_t bnx2x_start_xmit(struct sk_buff *skb, struct net_device *dev) if (unlikely(bnx2x_tx_avail(fp) < MAX_SKB_FRAGS + 3)) { netif_tx_stop_queue(txq); - /* We want bnx2x_tx_int to "see" the updated tx_bd_prod - if we put Tx into XOFF state. */ + + /* paired memory barrier is in bnx2x_tx_int(), we have to keep + * ordering of set_bit() in netif_tx_stop_queue() and read of + * fp->bd_tx_cons */ smp_mb(); + fp->eth_q_stats.driver_xoff++; if (bnx2x_tx_avail(fp) >= MAX_SKB_FRAGS + 3) netif_tx_wake_queue(txq); -- cgit v1.2.3