[netdrvr 8139too] fast poll for thread, if an unlikely race occurs

The rtl8139 thread is triggered only on rare 8139 hardware, the race itself is unlikely, and the impact of racing is low. We don't care enough to create a more-complex race-free solution. Rather, if the trylock fails, we now simply poll twice a second until we do get the lock.

[netdrvr 8139too] fast poll for thread, if an unlikely race occurs
The rtl8139 thread is triggered only on rare 8139 hardware, the race itself is unlikely, and the impact of racing is low. We don't care enough to create a more-complex race-free solution. Rather, if the trylock fails, we now simply poll twice a second until we do get the lock.
Jeff Garzik
1 parent 2f67bdb23d
Showing 1 changed file with 7 additions and 1 deletions Side-by-side Diff
drivers/net/8139too.c
@@ -1598,13 +1598,19 @@
 {
 	struct net_device *dev = _data;
 	struct rtl8139_private *tp = netdev_priv(dev);
+	unsigned long thr_delay;
  
 	if (rtnl_shlock_nowait() == 0) {
 		rtl8139_thread_iter (dev, tp, tp->mmio_addr);
 		rtnl_unlock ();
+
+		thr_delay = next_tick;
+	} else {
+		/* unlikely race.  mitigate with fast poll. */
+		thr_delay = HZ / 2;
 	}
  
-	schedule_delayed_work(&tp->thread, next_tick);
+	schedule_delayed_work(&tp->thread, thr_delay);
 }
  
 static void rtl8139_start_thread(struct rtl8139_private *tp)
...	...	@@ -1598,13 +1598,19 @@
1598	1598	{
1599	1599	struct net_device *dev = _data;
1600	1600	struct rtl8139_private *tp = netdev_priv(dev);
	1601	+ unsigned long thr_delay;
1601	1602
1602	1603	if (rtnl_shlock_nowait() == 0) {
1603	1604	rtl8139_thread_iter (dev, tp, tp->mmio_addr);
1604	1605	rtnl_unlock ();
	1606	+
	1607	+ thr_delay = next_tick;
	1608	+ } else {
	1609	+ /* unlikely race. mitigate with fast poll. */
	1610	+ thr_delay = HZ / 2;
1605	1611	}
1606	1612
1607		- schedule_delayed_work(&tp->thread, next_tick);
	1613	+ schedule_delayed_work(&tp->thread, thr_delay);
1608	1614	}
1609	1615
1610	1616	static void rtl8139_start_thread(struct rtl8139_private *tp)