Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754050Ab1DTKna (ORCPT ); Wed, 20 Apr 2011 06:43:30 -0400 Received: from cantor.suse.de ([195.135.220.2]:52458 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752180Ab1DTKn3 (ORCPT ); Wed, 20 Apr 2011 06:43:29 -0400 Date: Wed, 20 Apr 2011 12:43:27 +0200 Message-ID: From: Takashi Iwai To: Oliver Neukum Cc: Dave Jones , Linux Kernel , Jaroslav Kysela Subject: Re: lockdep trace when unplugging usb audio (.39rc4) In-Reply-To: <201104201232.44320.oneukum@suse.de> References: <20110419180745.GA438@redhat.com> <201104201232.44320.oneukum@suse.de> User-Agent: Wanderlust/2.15.6 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.7 Emacs/23.2 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2159 Lines: 68 At Wed, 20 Apr 2011 12:32:44 +0200, Oliver Neukum wrote: > > Am Dienstag, 19. April 2011, 20:07:45 schrieb Dave Jones: > > I get this trace when I unplug my NuForce uDAC. > > Please test this patch. Well, no, it would break the real fix for disconnection race we've done recently. Such a lockdep warning is sometimes seen, but I haven't seen the real deadlock by this in practice. It's a path from munmap -> release, and hits many other subsystems like NFS, if not fixed yet... thanks, Takashi > > Regards > Oliver > [2 0001-usb-audio-fix-potential-deadlock-on-unplug.patch ] > From 24d036ccb418d7cfa5a821d5a70b3d3da2d63bb3 Mon Sep 17 00:00:00 2001 > From: Oliver Neukum > Date: Wed, 20 Apr 2011 12:29:22 +0200 > Subject: [PATCH] usb-audio:fix potential deadlock on unplug > > Decrease the scope of a lock to fix a deadlock > > Signed-off-by: Oliver Neukum > --- > sound/usb/card.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/sound/usb/card.c b/sound/usb/card.c > index a90662a..1d3d9f0 100644 > --- a/sound/usb/card.c > +++ b/sound/usb/card.c > @@ -554,6 +554,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr) > mutex_lock(&chip->shutdown_mutex); > chip->shutdown = 1; > chip->num_interfaces--; > + mutex_unlock(&chip->shutdown_mutex); > if (chip->num_interfaces <= 0) { > snd_card_disconnect(card); > /* release the pcm resources */ > @@ -569,11 +570,9 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr) > snd_usb_mixer_disconnect(p); > } > usb_chip[chip->index] = NULL; > - mutex_unlock(&chip->shutdown_mutex); > mutex_unlock(®ister_mutex); > snd_card_free_when_closed(card); > } else { > - mutex_unlock(&chip->shutdown_mutex); > mutex_unlock(®ister_mutex); > } > } > -- > 1.7.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/