[PKT_SCHED]: Potential jiffy wrap bug in dev_watchdog().

There is a potential jiffy wraparound bug in the transmit watchdog
that is easily avoided by using time_after().
Signed-off-by: NStephen Hemminger <shemminger@osdl.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/sch_generic.c

@@ -193,8 +193,10 @@ static void dev_watchdog(unsigned long arg)
 		    netif_running(dev) &&
 		    netif_carrier_ok(dev)) {
 			if (netif_queue_stopped(dev) &&
-			    (jiffies - dev->trans_start) > dev->watchdog_timeo) {
-				printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n", dev->name);
+			    time_after(jiffies, dev->trans_start + dev->watchdog_timeo)) {
+
+				printk(KERN_INFO "NETDEV WATCHDOG: %s: transmit timed out\n",
+				       dev->name);
 				dev->tx_timeout(dev);
 			}
 			if (!mod_timer(&dev->watchdog_timer, jiffies + dev->watchdog_timeo))