[NETPOLL]: Fix TX queue overflow in trapped mode.

CONFIG_NETPOLL_TRAP causes the TX queue controls to be completely bypassed in
the netpoll's "trapped" mode which easily causes overflows in the drivers with
short TX queues (most notably, in 8139too with its 4-deep queue).  So, make
this option more sensible by making it only bypass the TX softirq wakeup.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Acked-by: Jeff Garzik <jgarzik@pobox.com>
Acked-by: Tom Rini <trini@kernel.crashing.org>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -654,8 +654,10 @@ static inline void netif_start_queue(struct net_device *dev)
 static inline void netif_wake_queue(struct net_device *dev)
 {
 #ifdef CONFIG_NETPOLL_TRAP
-	if (netpoll_trap())
+	if (netpoll_trap()) {
+		clear_bit(__LINK_STATE_XOFF, &dev->state);
 		return;
+	}
 #endif
 	if (test_and_clear_bit(__LINK_STATE_XOFF, &dev->state))
 		__netif_schedule(dev);
@@ -663,10 +665,6 @@ static inline void netif_wake_queue(struct net_device *dev)
 
 static inline void netif_stop_queue(struct net_device *dev)
 {
-#ifdef CONFIG_NETPOLL_TRAP
-	if (netpoll_trap())
-		return;
-#endif
 	set_bit(__LINK_STATE_XOFF, &dev->state);
 }