Subject: Re: [2.6.38-rc1] iwlagn lock misuse...
From: Johannes Berg <johannes@sipsolutions.net>
To: Daniel J Blueman <daniel.blueman@gmail.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>,
	Wey-Yi Guy <wey-yi.w.guy@intel.com>,
	Intel Linux Wireless <ilw@linux.intel.com>,
	linux-wireless@vger.kernel.org,
	Linux Kernel <linux-kernel@vger.kernel.org>
In-Reply-To: <AANLkTi=DLpfpLYAftktUKa5grNyTeT0-reyjEsrr-NwR@mail.gmail.com>
References: <AANLkTi=DLpfpLYAftktUKa5grNyTeT0-reyjEsrr-NwR@mail.gmail.com>
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Date: Wed, 19 Jan 2011 10:51:22 +0100
Message-ID: <1295430682.4685.1.camel@jlt3.sipsolutions.net>
Mime-Version: 1.0
Sender: linux-wireless-owner@vger.kernel.org

On Wed, 2011-01-19 at 16:44 +0700, Daniel J Blueman wrote:
> Booting an instrumented 2.6.38-rc1 kernel with an Intel WiFi Link 5300
> card and associating with an access point, I see a lockdep warning
> [attached].
> 
> This is essentially (struct iwl_priv)->lock being taken with
> interrupts disabled in iwl-agn-ict.c:152 [1] and the same lock taken
> with interrupts enabled in rx.c:2476 [2] (confirmed via disassembly).
> 
> It feels like this would have been introduced in this commit:
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=6e8cc38d5b05bb812f89a35bd9bf52405e67d0df

I think you're running into a lockdep false positive, it's not actually
the same lock and lockdep confuses a few skb queue locks. Please apply
this patch
http://git.kernel.org/?p=linux/kernel/git/linville/wireless-testing.git;a=commitdiff;h=53c16b8e752e8e58f4313f1155f3afadf78311bb
and see if the problem persists.

johannes