netxen: fix tx ring accounting

This forces every update of tx ring producer to check for
availability of space for next full TSO command. Earlier
firmware control commands didn't care to pause tx queue.

Stop the tx queue if there's not enough space to transmit one full
LSO command left on the tx ring after current transmit. This avoids
returning NETDEV_TX_BUSY after checking distance between producer
and consumer on every cpu.

Restart the tx queue only if we have cleaned up enough tx
descriptors.

Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 6 deletions

diff --git a/drivers/net/netxen/netxen_nic_init.c b/drivers/net/netxen/netxen_nic_init.c
index 6f77ad58e3b3..bdb143d2b5c7 100644
--- a/drivers/net/netxen/netxen_nic_init.c
+++ b/drivers/net/netxen/netxen_nic_init.c
@@ -1292,7 +1292,6 @@ int netxen_process_cmd_ring(struct netxen_adapter *adapter)
                 return 1;
 
         sw_consumer = tx_ring->sw_consumer;
-        barrier(); /* hw_consumer can change underneath */
         hw_consumer = le32_to_cpu(*(tx_ring->hw_consumer));
 
         while (sw_consumer != hw_consumer) {
@@ -1319,14 +1318,15 @@ int netxen_process_cmd_ring(struct netxen_adapter *adapter)
                         break;
         }
 
-        tx_ring->sw_consumer = sw_consumer;
-
         if (count && netif_running(netdev)) {
+                tx_ring->sw_consumer = sw_consumer;
+
                 smp_mb();
+
                 if (netif_queue_stopped(netdev) && netif_carrier_ok(netdev)) {
                         netif_tx_lock(netdev);
-                        netif_wake_queue(netdev);
-                        smp_mb();
+                        if (netxen_tx_avail(tx_ring) > TX_STOP_THRESH)
+                                netif_wake_queue(netdev);
                         netif_tx_unlock(netdev);
                 }
         }
@@ -1343,7 +1343,6 @@ int netxen_process_cmd_ring(struct netxen_adapter *adapter)
          * There is still a possible race condition and the host could miss an
          * interrupt. The card has to take care of this.
          */
-        barrier(); /* hw_consumer can change underneath */
         hw_consumer = le32_to_cpu(*(tx_ring->hw_consumer));
         done = (sw_consumer == hw_consumer);
         spin_unlock(&adapter->tx_clean_lock);