[PATCH] b43: fix shared IRQ race condition

[PATCH] b43: fix shared IRQ race condition

[Stefano Brivio]

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>

---

--- wireless-2.6/drivers/net/wireless/b43/main.c.orig	2007-11-07 17:55:30.553591943 +0100
+++ wireless-2.6/drivers/net/wireless/b43/main.c	2007-11-07 17:59:23.356020048 +0100
@@ -2979,6 +2979,16 @@
 
 	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);
@@ -2989,13 +2999,6 @@
 
 	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");


-- 
Ciao
Stefano

Re: [PATCH] b43: fix shared IRQ race condition

[Michael Buesch]

On Wednesday 07 November 2007 18:16:11 Stefano Brivio wrote:
> 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>
> 
> ---
> 
> --- wireless-2.6/drivers/net/wireless/b43/main.c.orig	2007-11-07 17:55:30.553591943 +0100
> +++ wireless-2.6/drivers/net/wireless/b43/main.c	2007-11-07 17:59:23.356020048 +0100
> @@ -2979,6 +2979,16 @@
>  
>  	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);
> @@ -2989,13 +2999,6 @@
>  
>  	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");
> 
> 

Acked-by: Michael Buesch <mb@bu3sch.de>

-- 
Greetings Michael.