sky2: Lock transmit queue while disabling device

netif_device_detach() does not take the tx_lock, so it's possible that
a call to sky2_xmit_frame is still in progress after
netif_device_detach() is complete.

Take netif_tx_lock() to make sure all transmits have stopped while
we're disabling the devices and that no other CPU is still
transmitting a frame after we've disabling the device.

Proposed fix for "sky2 panic under load" reported by Berck E. Nash.

Signed-off-by: Mike McCormack <mikem@ring3k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index faa48410195e..8ae8520baaf3 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -3176,7 +3176,9 @@ static void sky2_reset(struct sky2_hw *hw)
 static void sky2_detach(struct net_device *dev)
 {
         if (netif_running(dev)) {
+                netif_tx_lock(dev);
                 netif_device_detach(dev);       /* stop txq */
+                netif_tx_unlock(dev);
                 sky2_down(dev);
         }
 }