e1000: driver state fixes (race fix)

We were plagued by our interrupt handler posting a watchdog event which
could occur when our adapter was going down in case a late packet arrived
just before e1000_down() finished. This caused the watchdog timer to start
after the NIC was down and keep rescheduling it every N seconds. Once
the driver unloaded it would panic.

Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>

3 files changed, 23 insertions, 14 deletions

diff --git a/drivers/net/e1000/e1000.h b/drivers/net/e1000/e1000.h
index a9501e7b8ef9..7ecce438d258 100644
--- a/drivers/net/e1000/e1000.h
+++ b/drivers/net/e1000/e1000.h
@@ -345,8 +345,9 @@ struct e1000_adapter {
 };
 
 enum e1000_state_t {
-        __E1000_DRIVER_TESTING,
+        __E1000_TESTING,
         __E1000_RESETTING,
+        __E1000_DOWN
 };
 
 #endif /* _E1000_H_ */
diff --git a/drivers/net/e1000/e1000_ethtool.c b/drivers/net/e1000/e1000_ethtool.c
index 5edf8a099ceb..2cc949a34451 100644
--- a/drivers/net/e1000/e1000_ethtool.c
+++ b/drivers/net/e1000/e1000_ethtool.c
@@ -1624,7 +1624,7 @@ e1000_diag_test(struct net_device *netdev,
         struct e1000_adapter *adapter = netdev_priv(netdev);
         boolean_t if_running = netif_running(netdev);
 
-        set_bit(__E1000_DRIVER_TESTING, &adapter->flags);
+        set_bit(__E1000_TESTING, &adapter->flags);
         if (eth_test->flags == ETH_TEST_FL_OFFLINE) {
                 /* Offline tests */
 
@@ -1669,7 +1669,7 @@ e1000_diag_test(struct net_device *netdev,
                 adapter->hw.autoneg = autoneg;
 
                 e1000_reset(adapter);
-                clear_bit(__E1000_DRIVER_TESTING, &adapter->flags);
+                clear_bit(__E1000_TESTING, &adapter->flags);
                 if (if_running)
                         dev_open(netdev);
         } else {
@@ -1684,7 +1684,7 @@ e1000_diag_test(struct net_device *netdev,
                 data[2] = 0;
                 data[3] = 0;
 
-                clear_bit(__E1000_DRIVER_TESTING, &adapter->flags);
+                clear_bit(__E1000_TESTING, &adapter->flags);
         }
         msleep_interruptible(4 * 1000);
 }
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index e2615782966e..5098dd7df7cd 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -476,13 +476,14 @@ e1000_up(struct e1000_adapter *adapter)
 
         adapter->tx_queue_len = netdev->tx_queue_len;
 
-        mod_timer(&adapter->watchdog_timer, jiffies);
-
 #ifdef CONFIG_E1000_NAPI
         netif_poll_enable(netdev);
 #endif
         e1000_irq_enable(adapter);
 
+        clear_bit(__E1000_DOWN, &adapter->flags);
+
+        mod_timer(&adapter->watchdog_timer, jiffies + 2 * HZ);
         return 0;
 }
 
@@ -561,6 +562,10 @@ e1000_down(struct e1000_adapter *adapter)
 {
         struct net_device *netdev = adapter->netdev;
 
+        /* signal that we're down so the interrupt handler does not
+         * reschedule our watchdog timer */
+        set_bit(__E1000_DOWN, &adapter->flags);
+
         e1000_irq_disable(adapter);
 
         del_timer_sync(&adapter->tx_fifo_stall_timer);
@@ -903,11 +908,6 @@ e1000_probe(struct pci_dev *pdev,
         INIT_WORK(&adapter->reset_task,
                 (void (*)(void *))e1000_reset_task, netdev);
 
-        /* we're going to reset, so assume we have no link for now */
-
-        netif_carrier_off(netdev);
-        netif_stop_queue(netdev);
-
         e1000_check_options(adapter);
 
         /* Initial Wake on LAN setting
@@ -1014,6 +1014,10 @@ e1000_probe(struct pci_dev *pdev,
         if ((err = register_netdev(netdev)))
                 goto err_register;
 
+        /* tell the stack to leave us alone until e1000_open() is called */
+        netif_carrier_off(netdev);
+        netif_stop_queue(netdev);
+
         DPRINTK(PROBE, INFO, "Intel(R) PRO/1000 Network Connection\n");
 
         cards_found++;
@@ -1200,6 +1204,8 @@ e1000_sw_init(struct e1000_adapter *adapter)
         atomic_set(&adapter->irq_sem, 1);
         spin_lock_init(&adapter->stats_lock);
 
+        set_bit(__E1000_DOWN, &adapter->flags);
+
         return 0;
 }
 
@@ -1265,7 +1271,7 @@ e1000_open(struct net_device *netdev)
         int err;
 
         /* disallow open during test */
-        if (test_bit(__E1000_DRIVER_TESTING, &adapter->flags))
+        if (test_bit(__E1000_TESTING, &adapter->flags))
                 return -EBUSY;
 
         /* allocate transmit descriptors */
@@ -3072,7 +3078,7 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
         if (unlikely(adapter->hw.mac_type == e1000_82547)) {
                 if (unlikely(e1000_82547_fifo_workaround(adapter, skb))) {
                         netif_stop_queue(netdev);
-                        mod_timer(&adapter->tx_fifo_stall_timer, jiffies);
+                        mod_timer(&adapter->tx_fifo_stall_timer, jiffies + 1);
                         spin_unlock_irqrestore(&tx_ring->tx_lock, flags);
                         return NETDEV_TX_BUSY;
                 }
@@ -3468,7 +3474,9 @@ e1000_intr(int irq, void *data, struct pt_regs *regs)
                         rctl = E1000_READ_REG(hw, RCTL);
                         E1000_WRITE_REG(hw, RCTL, rctl & ~E1000_RCTL_EN);
                 }
-                mod_timer(&adapter->watchdog_timer, jiffies);
+                /* guard against interrupt when we're going down */
+                if (!test_bit(__E1000_DOWN, &adapter->flags))
+                        mod_timer(&adapter->watchdog_timer, jiffies + 1);
         }
 
 #ifdef CONFIG_E1000_NAPI