[PATCH net-drivers-2.6 2/5] ixgb: Avoid race e1000_watchdog and ixgb_clean_tx_irq

[Malli Chilakala <mallikarjuna.chilakala@xxxxxxxxx>]

2 Avoid race between e1000_watchdog and ixgb_clean_tx_irq
Signed-off-by: Mallikarjuna R Chilakala <mallikarjuna.chilakala@xxxxxxxxx>
Signed-off-by: Ganesh Venkatesan <ganesh.venkatesan@xxxxxxxxx>
Signed-off-by: John Ronciak <john.ronciak@xxxxxxxxx>
diff -up net-drivers-2.6/drivers/net/ixgb/ixgb.h 
net-drivers-2.6/drivers/net/ixgb.new/ixgb.h
--- net-drivers-2.6/drivers/net/ixgb/ixgb.h     2005-02-06 23:33:00.651031496 
-0800
+++ net-drivers-2.6/drivers/net/ixgb.new/ixgb.h 2005-02-06 23:33:01.521899104 
-0800
@@ -176,6 +176,7 @@ struct ixgb_adapter {
        uint64_t hw_csum_tx_error;
        uint32_t tx_int_delay;
        boolean_t tx_int_delay_enable;
+       boolean_t detect_tx_hung;
 
        /* RX */
        struct ixgb_desc_ring rx_ring;
diff -up net-drivers-2.6/drivers/net/ixgb/ixgb_main.c 
net-drivers-2.6/drivers/net/ixgb.new/ixgb_main.c
--- net-drivers-2.6/drivers/net/ixgb/ixgb_main.c        2005-02-06 
23:33:00.652031344 -0800
+++ net-drivers-2.6/drivers/net/ixgb.new/ixgb_main.c    2005-02-06 
23:33:01.617884512 -0800
@@ -1100,7 +1100,6 @@ ixgb_watchdog(unsigned long data)
        struct ixgb_adapter *adapter = (struct ixgb_adapter *)data;
        struct net_device *netdev = adapter->netdev;
        struct ixgb_desc_ring *txdr = &adapter->tx_ring;
-       unsigned int i;
 
        ixgb_check_for_link(&adapter->hw);
 
@@ -1143,12 +1140,8 @@ ixgb_watchdog(unsigned long data)
                }
        }
 
-       /* Early detection of hung controller */
-       i = txdr->next_to_clean;
-       if(txdr->buffer_info[i].dma &&
-          time_after(jiffies, txdr->buffer_info[i].time_stamp + HZ) &&
-          !(IXGB_READ_REG(&adapter->hw, STATUS) & IXGB_STATUS_TXOFF))
-               netif_stop_queue(netdev);
+       /* Force detection of hung controller every watchdog period */
+       adapter->detect_tx_hung = TRUE;
 
        /* generate an interrupt to force clean up of any stragglers */
        IXGB_WRITE_REG(&adapter->hw, ICS, IXGB_INT_TXDW);
@@ -1748,6 +1748,17 @@ ixgb_clean_tx_irq(struct ixgb_adapter *a
        }
        spin_unlock(&adapter->tx_lock);
 
+       if(adapter->detect_tx_hung) {
+               /* detect a transmit hang in hardware, this serializes the
+                * check with the clearing of time_stamp and movement of i */
+               adapter->detect_tx_hung = FALSE;
+               if(tx_ring->buffer_info[i].dma &&
+                  time_after(jiffies, tx_ring->buffer_info[i].time_stamp + HZ)
+                  && !(IXGB_READ_REG(&adapter->hw, STATUS) &
+                       IXGB_STATUS_TXOFF))
+                       netif_stop_queue(netdev);
+       }
+
        return cleaned;
 }