[NET]: fix carrier-on bug?

While looking at a net driver with the following construct,

	if (!netif_carrier_ok(dev))
		netif_carrier_on(dev);

it stuck me that the netif_carrier_ok() check was redundant, since
netif_carrier_on() checks bit __LINK_STATE_NOCARRIER anyway.  This is
the same reason why netif_queue_stopped() need not be called prior to
netif_wake_queue().

This is true, but there is however an unwanted side effect from assuming
that netif_carrier_on() can be called multiple times:  it touches the
watchdog, regardless of pre-existing carrier state.

The fix:  move watchdog-up inside the bit-cleared code path.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 95ae11956f35..e01d57692c9a 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -249,10 +249,11 @@ static void dev_watchdog_down(struct net_device *dev)
  */
 void netif_carrier_on(struct net_device *dev)
 {
-        if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state))
+        if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
                 linkwatch_fire_event(dev);
-        if (netif_running(dev))
-                __netdev_watchdog_up(dev);
+                if (netif_running(dev))
+                        __netdev_watchdog_up(dev);
+        }
 }
 
 /**