Re: [PATCH] wl12xx: Fix kernel crash related to hw recovery and interface shutdown

[Luciano Coelho <luciano.coelho@nokia.com>]

On Thu, 2010-11-18 at 15:19 +0200, juuso.oikarinen@nokia.com wrote:
> From: Juuso Oikarinen <juuso.oikarinen@nokia.com>
> 
> It is possible that the op_remove_interface function  is invoked exactly at
> the same time has hw recovery is started. In this case it is possible for the
> interface to be already removed in the op_remove_interface call, which
> currently leads to a kernel warning and a subsequent kernel crash.
> 
> Fix this by ignoring the op_remove_interface call if the interface is already
> down at that point.
> 
> Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
> ---

[...]

> diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c
> index 31f0e2f..11b0477 100644
> --- a/drivers/net/wireless/wl12xx/main.c
> +++ b/drivers/net/wireless/wl12xx/main.c
> @@ -1157,10 +1157,16 @@ static void wl1271_op_remove_interface(struct ieee80211_hw *hw,
>  	struct wl1271 *wl = hw->priv;
>  
>  	mutex_lock(&wl->mutex);
> -	WARN_ON(wl->vif != vif);
> -	__wl1271_op_remove_interface(wl);
> -	mutex_unlock(&wl->mutex);
> +	/*
> +	 * wl->vif can be null here if someone shuts down the interface
> +	 * just when hardware recovery has been started.
> +	 */
> +	if (wl->vif) {
> +		WARN_ON(wl->vif != vif);
> +		__wl1271_op_remove_interface(wl);
> +	}

Should you still remove the interface if the vif you received is wrong?
Surely, something is totally wrong if you get a different vif, but maybe
removing the interface here will just confuse things even more?

 
> +	mutex_unlock(&wl->mutex);
>  	cancel_work_sync(&wl->recovery_work);
>  }
>  


-- 
Cheers,
Luca.