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authorVladislav Zolotarov <vladz@broadcom.com>2010-02-28 00:12:02 +0000
committerDavid S. Miller <davem@davemloft.net>2010-02-28 18:37:12 -0800
commitc16cc0b464b8876cfd57ce1c1dbcb6f9a6a0bce3 (patch)
tree8f70b0b1a48a5e9e2ad44d7d446936a75a936215
parent76dadd76c265a0cdb5a76aa4eef03fcc9639b388 (diff)
bnx2x: Tx barriers and locks
[Resending with the proper subject. Sorry for the mess. ] This patch is based on the RFC of Stanislaw Gruszka. More specifically it fixes two possible races: - One, described by Stanislaw, may lead to permanent disabling of the Tx queue. This is fixed by adding the smp_wmb() to propagate the BD consumer change towards the memory. - Second may lead to bnx2x_start_xmit() returning NETDEV_TX_BUSY. This is fixed by taking a tx_lock() before rechecking the number of available Tx BDs. thanks, vlad Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Vladislav Zolotarov <vladz@broadcom.com> Signed-off-by: Eilon Greenstein <eilong@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/bnx2x_main.c31
1 files changed, 22 insertions, 9 deletions
diff --git a/drivers/net/bnx2x_main.c b/drivers/net/bnx2x_main.c
index 5adf2a05246f..ed785a30e98b 100644
--- a/drivers/net/bnx2x_main.c
+++ b/drivers/net/bnx2x_main.c
@@ -57,8 +57,8 @@
#include "bnx2x_init_ops.h"
#include "bnx2x_dump.h"
-#define DRV_MODULE_VERSION "1.52.1-6"
-#define DRV_MODULE_RELDATE "2010/02/16"
+#define DRV_MODULE_VERSION "1.52.1-7"
+#define DRV_MODULE_RELDATE "2010/02/28"
#define BNX2X_BC_VER 0x040200
#include <linux/firmware.h>
@@ -957,21 +957,34 @@ static int bnx2x_tx_int(struct bnx2x_fastpath *fp)
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_wmb();
+
/* TBD need a thresh? */
if (unlikely(netif_tx_queue_stopped(txq))) {
-
- /* 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.
+ /* Taking tx_lock() is needed to prevent reenabling the queue
+ * while it's empty. This could have happen if rx_action() gets
+ * suspended in bnx2x_tx_int() after the condition before
+ * netif_tx_wake_queue(), while tx_action (bnx2x_start_xmit()):
+ *
+ * stops the queue->sees fresh tx_bd_cons->releases the queue->
+ * sends some packets consuming the whole queue again->
+ * stops the queue
*/
- smp_mb();
+
+ __netif_tx_lock(txq, smp_processor_id());
if ((netif_tx_queue_stopped(txq)) &&
(bp->state == BNX2X_STATE_OPEN) &&
(bnx2x_tx_avail(fp) >= MAX_SKB_FRAGS + 3))
netif_tx_wake_queue(txq);
+
+ __netif_tx_unlock(txq);
}
return 0;
}