net: systemport: avoid unbalanced enable_irq_wake calls

Multiple enable_irq_wake() calls will keep increasing the IRQ
wake_depth, which ultimately leads to the following types of
situation:

1) enable Wake-on-LAN interrupt w/o password
2) enable Wake-on-LAN interrupt w/ password
3) enable Wake-on-LAN interrupt w/o password
4) disable Wake-on-LAN interrupt

After step 4), SYSTEMPORT would always wake-up the system no matter what
wake-up device we use, which is not what we want. Fix this by making
sure there are no unbalanced enable_irq_wake() calls.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -436,7 +436,8 @@ static int bcm_sysport_set_wol(struct net_device *dev,
 	/* Flag the device and relevant IRQ as wakeup capable */
 	if (wol->wolopts) {
 		device_set_wakeup_enable(kdev, 1);
-		enable_irq_wake(priv->wol_irq);
+		if (priv->wol_irq_disabled)
+			enable_irq_wake(priv->wol_irq);
 		priv->wol_irq_disabled = 0;
 	} else {
 		device_set_wakeup_enable(kdev, 0);