e1000: fix occasional panic on unload

Net drivers in general have an issue where timers fired
by mod_timer or work threads with schedule_work are running
outside of the rtnl_lock.

With no other lock protection these routines are vulnerable
to races with driver unload or reset paths.

The longer term solution to this might be a redesign with
safer locks being taken in the driver to guarantee no
reentrance, but for now a safe and effective fix is
to take the rtnl_lock in these routines.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 5b4c6c061414734dac43552a6e2040af447ef6ef..c88439deb7d827b0ab7d3379b4f60b0fea535a0f 100644 (file)
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -521,8 +521,21 @@ void e1000_down(struct e1000_adapter *adapter)
        e1000_clean_all_rx_rings(adapter);
 }
 
+void e1000_reinit_safe(struct e1000_adapter *adapter)
+{
+       while (test_and_set_bit(__E1000_RESETTING, &adapter->flags))
+               msleep(1);
+       rtnl_lock();
+       e1000_down(adapter);
+       e1000_up(adapter);
+       rtnl_unlock();
+       clear_bit(__E1000_RESETTING, &adapter->flags);
+}
+
 void e1000_reinit_locked(struct e1000_adapter *adapter)
 {
+       /* if rtnl_lock is not held the call path is bogus */
+       ASSERT_RTNL();
        WARN_ON(in_interrupt());
        while (test_and_set_bit(__E1000_RESETTING, &adapter->flags))
                msleep(1);
@@ -2247,7 +2260,10 @@ static void e1000_update_phy_info_task(struct work_struct *work)
                                                     struct e1000_adapter,
                                                     phy_info_task);
        struct e1000_hw *hw = &adapter->hw;
+
+       rtnl_lock();
        e1000_phy_get_info(hw, &adapter->phy_info);
+       rtnl_unlock();
 }
 
 /**
@@ -2273,6 +2289,7 @@ static void e1000_82547_tx_fifo_stall_task(struct work_struct *work)
        struct net_device *netdev = adapter->netdev;
        u32 tctl;
 
+       rtnl_lock();
        if (atomic_read(&adapter->tx_fifo_stall)) {
                if ((er32(TDT) == er32(TDH)) &&
                   (er32(TDFT) == er32(TDFH)) &&
@@ -2293,6 +2310,7 @@ static void e1000_82547_tx_fifo_stall_task(struct work_struct *work)
                        mod_timer(&adapter->tx_fifo_stall_timer, jiffies + 1);
                }
        }
+       rtnl_unlock();
 }
 
 bool e1000_has_link(struct e1000_adapter *adapter)
@@ -3160,7 +3178,7 @@ static void e1000_reset_task(struct work_struct *work)
        struct e1000_adapter *adapter =
                container_of(work, struct e1000_adapter, reset_task);
 
-       e1000_reinit_locked(adapter);
+       e1000_reinit_safe(adapter);
 }
 
 /**