netxen: fix race in tx stop queue

There is race between netif_stop_queue and netif_stopped_queue
check.So check once again if buffers are available to avoid race.
With above logic we can also get rid of tx lock in process_cmd_ring.

Signed-off-by: Rajesh Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 22 insertions, 18 deletions

diff --git a/drivers/net/netxen/netxen_nic.h b/drivers/net/netxen/netxen_nic.h
index 6dca3574e355..92f89af0720e 100644
--- a/drivers/net/netxen/netxen_nic.h
+++ b/drivers/net/netxen/netxen_nic.h
@@ -175,7 +175,10 @@
 #define MAX_NUM_CARDS           4
 
 #define MAX_BUFFERS_PER_CMD     32
-#define TX_STOP_THRESH          ((MAX_SKB_FRAGS >> 2) + 4)
+#define MAX_TSO_HEADER_DESC     2
+#define MGMT_CMD_DESC_RESV      4
+#define TX_STOP_THRESH          ((MAX_SKB_FRAGS >> 2) + MAX_TSO_HEADER_DESC \
+                                                        + MGMT_CMD_DESC_RESV)
 #define NX_MAX_TX_TIMEOUTS      2
 
 /*
diff --git a/drivers/net/netxen/netxen_nic_hw.c b/drivers/net/netxen/netxen_nic_hw.c
index 29d7b93d0493..10e2f13d8903 100644
--- a/drivers/net/netxen/netxen_nic_hw.c
+++ b/drivers/net/netxen/netxen_nic_hw.c
@@ -598,8 +598,14 @@ netxen_send_cmd_descs(struct netxen_adapter *adapter,
 
         if (nr_desc >= netxen_tx_avail(tx_ring)) {
                 netif_tx_stop_queue(tx_ring->txq);
-                __netif_tx_unlock_bh(tx_ring->txq);
-                return -EBUSY;
+                smp_mb();
+                if (netxen_tx_avail(tx_ring) > nr_desc) {
+                        if (netxen_tx_avail(tx_ring) > TX_STOP_THRESH)
+                                netif_tx_wake_queue(tx_ring->txq);
+                } else {
+                        __netif_tx_unlock_bh(tx_ring->txq);
+                        return -EBUSY;
+                }
         }
 
         do {
diff --git a/drivers/net/netxen/netxen_nic_init.c b/drivers/net/netxen/netxen_nic_init.c
index a2d805aa75cd..95fe552aa279 100644
--- a/drivers/net/netxen/netxen_nic_init.c
+++ b/drivers/net/netxen/netxen_nic_init.c
@@ -1763,14 +1763,10 @@ int netxen_process_cmd_ring(struct netxen_adapter *adapter)
 
                 smp_mb();
 
-                if (netif_queue_stopped(netdev) && netif_carrier_ok(netdev)) {
-                        __netif_tx_lock(tx_ring->txq, smp_processor_id());
-                        if (netxen_tx_avail(tx_ring) > TX_STOP_THRESH) {
+                if (netif_queue_stopped(netdev) && netif_carrier_ok(netdev))
+                        if (netxen_tx_avail(tx_ring) > TX_STOP_THRESH)
                                 netif_wake_queue(netdev);
-                                adapter->tx_timeo_cnt = 0;
-                        }
-                        __netif_tx_unlock(tx_ring->txq);
-                }
+                adapter->tx_timeo_cnt = 0;
         }
         /*
          * If everything is freed up to consumer then check if the ring is full
diff --git a/drivers/net/netxen/netxen_nic_main.c b/drivers/net/netxen/netxen_nic_main.c
index 2c6ceeb592b3..83ee5544aced 100644
--- a/drivers/net/netxen/netxen_nic_main.c
+++ b/drivers/net/netxen/netxen_nic_main.c
@@ -125,11 +125,6 @@ netxen_nic_update_cmd_producer(struct netxen_adapter *adapter,
                 struct nx_host_tx_ring *tx_ring)
 {
         NXWRIO(adapter, tx_ring->crb_cmd_producer, tx_ring->producer);
-
-        if (netxen_tx_avail(tx_ring) <= TX_STOP_THRESH) {
-                netif_stop_queue(adapter->netdev);
-                smp_mb();
-        }
 }
 
 static uint32_t crb_cmd_consumer[4] = {
@@ -1209,7 +1204,7 @@ netxen_setup_netdev(struct netxen_adapter *adapter,
                 adapter->max_mc_count = 16;
 
         netdev->netdev_ops         = &netxen_netdev_ops;
-        netdev->watchdog_timeo     = 2*HZ;
+        netdev->watchdog_timeo     = 5*HZ;
 
         netxen_nic_change_mtu(netdev, netdev->mtu);
 
@@ -1825,9 +1820,13 @@ netxen_nic_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
         /* 4 fragments per cmd des */
         no_of_desc = (frag_count + 3) >> 2;
 
-        if (unlikely(no_of_desc + 2 > netxen_tx_avail(tx_ring))) {
+        if (unlikely(netxen_tx_avail(tx_ring) <= TX_STOP_THRESH)) {
                 netif_stop_queue(netdev);
-                return NETDEV_TX_BUSY;
+                smp_mb();
+                if (netxen_tx_avail(tx_ring) > TX_STOP_THRESH)
+                        netif_start_queue(netdev);
+                else
+                        return NETDEV_TX_BUSY;
         }
 
         producer = tx_ring->producer;