From: Michael Buesch <mb@bu3sch.de>
To: Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [PATCH] b43: fix ieee80211_rx() context
Date: Sun, 11 Oct 2009 12:26:42 +0200
Cc: John Linville <linville@tuxdriver.com>,
	David Miller <davem@davemloft.net>,
	Kalle Valo <kalle.valo@iki.fi>,
	Dave Young <hidave.darkstar@gmail.com>,
	linux-wireless <linux-wireless@vger.kernel.org>
References: <1255256361.4095.56.camel@johannes.local>
In-Reply-To: <1255256361.4095.56.camel@johannes.local>
MIME-Version: 1.0
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Message-Id: <200910111226.44778.mb@bu3sch.de>
Sender: linux-wireless-owner@vger.kernel.org

On Sunday 11 October 2009 12:19:21 Johannes Berg wrote:
> Due to the way it interacts with the networking
> stack and other parts of mac80211, ieee80211_rx()
> must be called with disabled softirqs.

Is this stated in the documentation somewhere?

> Michael, the former maintainer of this driver,
> has refused to fix the problem this way instead
> proposing a much more invasive patch that could
> not even be proved correct wrt. locking inside
> mac80211. Regardless of that, he believes this
> to be a bug in mac80211, and has also publicly
> stated [1] that he does not care about this even
> though it is a regression introduced by his own
> patches.

What if we leave slander out of the commit messages?

> Since nobody else seems to be wanting to fix the
> problem, I'll just fix it for the benefit of the
> many users of this driver.
> 
> [1] http://thread.gmane.org/gmane.linux.kernel.wireless.general/39440/focus=40266
> 
> Reported-by: Dave Young <hidave.darkstar@gmail.com>
> Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
> ---
>  drivers/net/wireless/b43/xmit.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> --- wireless-testing.orig/drivers/net/wireless/b43/xmit.c	2009-10-11 12:11:50.000000000 +0200
> +++ wireless-testing/drivers/net/wireless/b43/xmit.c	2009-10-11 12:12:06.000000000 +0200
> @@ -690,7 +690,10 @@ void b43_rx(struct b43_wldev *dev, struc
>  	}
>  
>  	memcpy(IEEE80211_SKB_RXCB(skb), &status, sizeof(status));
> +
> +	local_bh_disable();
>  	ieee80211_rx(dev->wl->hw, skb);
> +	local_bh_enable();
>  
>  #if B43_DEBUG
>  	dev->rx_count++;


-- 
Greetings, Michael.