From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752159AbbFYJgY (ORCPT ); Thu, 25 Jun 2015 05:36:24 -0400 Received: from mail-pd0-f170.google.com ([209.85.192.170]:33667 "EHLO mail-pd0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751031AbbFYJgH (ORCPT ); Thu, 25 Jun 2015 05:36:07 -0400 From: Nicolas Boichat To: Mark Brown Cc: Mauro Carvalho Chehab , Antti Palosaari , Ingo Molnar , Arjan van de Ven , Lars-Peter Clausen , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Bard Liao , Oder Chiou , Liam Girdwood , Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, Anatol Pomozov Subject: [RFC PATCH 2/2] ASoC: rt5677: Add lockdep class to silence lockdep warnings Date: Thu, 25 Jun 2015 17:35:04 +0800 Message-Id: <1435224904-35517-2-git-send-email-drinkcat@chromium.org> X-Mailer: git-send-email 2.4.3.573.g4eafbef In-Reply-To: <1435224904-35517-1-git-send-email-drinkcat@chromium.org> References: <1435224904-35517-1-git-send-email-drinkcat@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Accessing rt5677->regmap requires read/write operations on another regmap (rt5677->regmap_physical), which causes the lockdep detector to throw a false warning, as both regmaps are using the same lockdep class by default. Introduce a new class for rt5677->regmap to silence this warning. Sample warning: [ 2.569449] ============================================= [ 2.569451] [ INFO: possible recursive locking detected ] [ 2.569454] 3.18.0 #311 Tainted: G S [ 2.569456] --------------------------------------------- [ 2.569458] swapper/0/1 is trying to acquire lock: [ 2.569469] (&map->mutex){+.+...}, at: [] regmap_lock_mutex+0x10/0x18 [ 2.569470] [ 2.569470] but task is already holding lock: [ 2.569476] (&map->mutex){+.+...}, at: [] regmap_lock_mutex+0x10/0x18 [ 2.569478] [ 2.569478] other info that might help us debug this: [ 2.569479] Possible unsafe locking scenario: [ 2.569479] [ 2.569480] CPU0 [ 2.569481] ---- [ 2.569484] lock(&map->mutex); [ 2.569486] lock(&map->mutex); [ 2.569487] [ 2.569487] *** DEADLOCK *** [ 2.569487] [ 2.569489] May be due to missing lock nesting notation [ 2.569489] [ 2.569491] 3 locks held by swapper/0/1: [ 2.569499] #0: (&dev->mutex){......}, at: [] __driver_attach+0x38/0x98 [ 2.569505] #1: (&dev->mutex){......}, at: [] __driver_attach+0x58/0x98 [ 2.569512] #2: (&map->mutex){+.+...}, at: [] regmap_lock_mutex+0x10/0x18 [ 2.569513] [ 2.569513] stack backtrace: [ 2.569517] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G S 3.18.0 #311 [ 2.569521] Call trace: [ 2.569527] [] dump_backtrace+0x0/0x108 [ 2.569530] [] show_stack+0x10/0x1c [ 2.569535] [] dump_stack+0x74/0x94 [ 2.569540] [] __lock_acquire+0x73c/0x1910 [ 2.569544] [] lock_acquire+0xec/0x128 [ 2.569548] [] mutex_lock_nested+0x58/0x354 [ 2.569551] [] regmap_lock_mutex+0xc/0x18 [ 2.569554] [] regmap_read+0x34/0x68 [ 2.569559] [] rt5677_read+0x9c/0xb4 [ 2.569562] [] _regmap_read+0xa8/0x138 [ 2.569565] [] regmap_read+0x44/0x68 [ 2.569569] [] rt5677_i2c_probe+0x25c/0x4a4 [ 2.569574] [] i2c_device_probe+0xfc/0x130 [ 2.569577] [] driver_probe_device+0xd4/0x23c [ 2.569580] [] __driver_attach+0x68/0x98 [ 2.569584] [] bus_for_each_dev+0x70/0x90 [ 2.569588] [] driver_attach+0x1c/0x28 [ 2.569591] [] bus_add_driver+0xd8/0x1e0 [ 2.569594] [] driver_register+0xbc/0x10c [ 2.569598] [] i2c_register_driver+0x48/0xac [ 2.569601] [] rt5677_i2c_driver_init+0x14/0x20 [ 2.569605] [] do_one_initcall+0xf4/0x18c [ 2.569609] [] kernel_init_freeable+0x144/0x1e4 [ 2.569613] [] kernel_init+0x10/0xd4 Signed-off-by: Nicolas Boichat --- sound/soc/codecs/rt5677.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/sound/soc/codecs/rt5677.c b/sound/soc/codecs/rt5677.c index 31d969a..3007d13 100644 --- a/sound/soc/codecs/rt5677.c +++ b/sound/soc/codecs/rt5677.c @@ -4998,6 +4998,7 @@ static const struct regmap_config rt5677_regmap_physical = { .num_ranges = ARRAY_SIZE(rt5677_ranges), }; +static struct lock_class_key rt5677_regmap_key; static const struct regmap_config rt5677_regmap = { .reg_bits = 8, .val_bits = 16, @@ -5015,6 +5016,10 @@ static const struct regmap_config rt5677_regmap = { .num_reg_defaults = ARRAY_SIZE(rt5677_reg), .ranges = rt5677_ranges, .num_ranges = ARRAY_SIZE(rt5677_ranges), + + /* Silence incorrect lockdep warnings, as rt5677_regmap_physical is + * accessed from within rt5677_regmap. */ + .lockdep_lock_class_key = &rt5677_regmap_key, }; static const struct i2c_device_id rt5677_i2c_id[] = { -- 2.4.3.573.g4eafbef