b43: fix shared IRQ race condition

Fix an IRQ race condition in b43. If we call b43_stop_wireless_core(), it
will set the status of the device to INITIALIZED and the IRQ handler won't
care any longer about IRQs, thus the kernel will disable the IRQ if it's
shared (unless we boot it with the 'irqpoll' option). So we must disable
IRQs before changing the device status.

Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/main.c

@@ -2985,6 +2985,16 @@ static void b43_wireless_core_stop(struct b43_wldev *dev)
 
 	if (b43_status(dev) < B43_STAT_STARTED)
 		return;
+
+	/* Disable and sync interrupts. We must do this before than
+	 * setting the status to INITIALIZED, as the interrupt handler
+	 * won't care about IRQs then. */
+	spin_lock_irqsave(&wl->irq_lock, flags);
+	dev->irq_savedstate = b43_interrupt_disable(dev, B43_IRQ_ALL);
+	b43_read32(dev, B43_MMIO_GEN_IRQ_MASK);	/* flush */
+	spin_unlock_irqrestore(&wl->irq_lock, flags);
+	b43_synchronize_irq(dev);
+
 	b43_set_status(dev, B43_STAT_INITIALIZED);
 
 	mutex_unlock(&wl->mutex);
@@ -2995,13 +3005,6 @@ static void b43_wireless_core_stop(struct b43_wldev *dev)
 
 	ieee80211_stop_queues(wl->hw);	//FIXME this could cause a deadlock, as mac80211 seems buggy.
 
-	/* Disable and sync interrupts. */
-	spin_lock_irqsave(&wl->irq_lock, flags);
-	dev->irq_savedstate = b43_interrupt_disable(dev, B43_IRQ_ALL);
-	b43_read32(dev, B43_MMIO_GEN_IRQ_MASK);	/* flush */
-	spin_unlock_irqrestore(&wl->irq_lock, flags);
-	b43_synchronize_irq(dev);
-
 	b43_mac_suspend(dev);
 	free_irq(dev->dev->irq, dev);
 	b43dbg(wl, "Wireless interface stopped\n");