From owner-freebsd-hackers@freebsd.org  Wed Mar 30 09:44:42 2016
Return-Path: <owner-freebsd-hackers@freebsd.org>
Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id C58C6AE17CE
 for <freebsd-hackers@mailman.ysv.freebsd.org>;
 Wed, 30 Mar 2016 09:44:42 +0000 (UTC) (envelope-from hps@selasky.org)
Received: from mail.turbocat.net (heidi.turbocat.net [88.198.202.214])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 9142A1E0C;
 Wed, 30 Mar 2016 09:44:42 +0000 (UTC) (envelope-from hps@selasky.org)
Received: from laptop015.home.selasky.org (unknown [62.141.129.119])
 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits))
 (No client certificate requested)
 by mail.turbocat.net (Postfix) with ESMTPSA id 888FE1FE023;
 Wed, 30 Mar 2016 11:44:40 +0200 (CEST)
Subject: Re: I need a little help in fixing `exclusive sleep mutex
 urtwn0_com_lock` in CURRENT
To: Aleksander Alekseev <mail@eax.me>, freebsd-hackers@freebsd.org,
 Adrian Chadd <adrian@freebsd.org>
References: <20160330123048.3361a9e4@fujitsu>
From: Hans Petter Selasky <hps@selasky.org>
Message-ID: <56FBA0C0.8030809@selasky.org>
Date: Wed, 30 Mar 2016 11:47:44 +0200
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:38.0) Gecko/20100101
 Thunderbird/38.5.0
MIME-Version: 1.0
In-Reply-To: <20160330123048.3361a9e4@fujitsu>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.21
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers/>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 30 Mar 2016 09:44:42 -0000

On 03/30/16 11:30, Aleksander Alekseev wrote:
> So as I understand some code acquired a mutex and didn't release it.
> And naturally it has something to do with USB. Now how can I figure out
> what code acquired this lock? Best approach I can think of currently is
> to find all places where this lock is accessed and add a debug logging.
> But perhaps there is a better way?

Looks like the USB driver or WLAN stack needs to drain this taskqueue 
before detaching. Maybe Adrian knows?

--HPS