From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755267AbdL1SZk (ORCPT ); Thu, 28 Dec 2017 13:25:40 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:58733 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753966AbdL1RNQ (ORCPT ); Thu, 28 Dec 2017 12:13:16 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Takashi Iwai" , "syzbot" Date: Thu, 28 Dec 2017 16:59:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 79/94] ALSA: seq: Avoid invalid lockdep class warning In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.97-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 3510c7aa069aa83a2de6dab2b41401a198317bdc upstream. The recent fix for adding rwsem nesting annotation was using the given "hop" argument as the lock subclass key. Although the idea itself works, it may trigger a kernel warning like: BUG: looking up invalid subclass: 8 .... since the lockdep has a smaller number of subclasses (8) than we currently allow for the hops there (10). The current definition is merely a sanity check for avoiding the too deep delivery paths, and the 8 hops are already enough. So, as a quick fix, just follow the max hops as same as the max lockdep subclasses. Fixes: 1f20f9ff57ca ("ALSA: seq: Fix nested rwsem annotation for lockdep splat") Reported-by: syzbot Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- include/sound/seq_kernel.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/include/sound/seq_kernel.h +++ b/include/sound/seq_kernel.h @@ -55,7 +55,8 @@ typedef union snd_seq_timestamp snd_seq_ #define SNDRV_SEQ_DEFAULT_CLIENT_EVENTS 200 /* max delivery path length */ -#define SNDRV_SEQ_MAX_HOPS 10 +/* NOTE: this shouldn't be greater than MAX_LOCKDEP_SUBCLASSES */ +#define SNDRV_SEQ_MAX_HOPS 8 /* max size of event size */ #define SNDRV_SEQ_MAX_EVENT_LEN 0x3fffffff