linux-kernel - [PATCH] ASoC: mediatek: mt8186: Fix mutex double unlock in GPIO request

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Message-Id: <20220617100632.1447811-1-fshao@chromium.org>
Date:   Fri, 17 Jun 2022 18:06:33 +0800
From:   Fei Shao <fshao@...omium.org>
To:     Mark Brown <broonie@...nel.org>, Jiaxin Yu <jiaxin.yu@...iatek.com>
Cc:     Fei Shao <fshao@...omium.org>, alsa-devel@...a-project.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org
Subject: [PATCH] ASoC: mediatek: mt8186: Fix mutex double unlock in GPIO request

The lockdep mechanism reveals an unbalanced unlocking on MT8186:

  [    2.993966] WARNING: bad unlock balance detected!
  [    2.993971] 5.15.46-421fef3b44d7-lockdep #16 Not tainted
  [    2.993978] -------------------------------------
  [    2.993983] kworker/u16:1/10 is trying to release lock (gpio_request_mutex) at:
  [    2.993994] [<ffffffdcd9adebf8>] mt8186_afe_gpio_request+0xf8/0x210
  [    2.994012] but there are no more locks to release!
  [    2.994017]
  [    2.994017] other info that might help us debug this:
  [    2.994022] 3 locks held by kworker/u16:1/10:
  [    2.994028]  #0: ffffff80c004a148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1a8/0x364
  [    2.994054]  #1: ffffffc0080d3d58 (deferred_probe_work){+.+.}-{0:0}, at: process_one_work+0x1d0/0x364
  [    2.994074]  #2: ffffff80c12ab9a0 (&dev->mutex){....}-{3:3}, at: __device_attach+0x44/0x150
  [    2.994096]
  [    2.994096] stack backtrace:
  [    2.994102] CPU: 6 PID: 10 Comm: kworker/u16:1 Not tainted 5.15.46-421fef3b44d7-lockdep #16 a2af0e2c6b3eeab6799b5aa8091c1d05d3a7bbb1
  [    2.994113] Hardware name: Google Kingler board (DT)
  [    2.994120] Workqueue: events_unbound deferred_probe_work_func
  [    2.994130] Call trace:
  [    2.994135]  dump_backtrace+0x0/0x1d4
  [    2.994144]  show_stack+0x20/0x2c
  [    2.994152]  dump_stack_lvl+0x78/0x9c
  [    2.994163]  dump_stack+0x18/0x44
  [    2.994172]  print_unlock_imbalance_bug+0xf0/0xf4
  [    2.994184]  lock_release+0x150/0x388
  [    2.994193]  __mutex_unlock_slowpath+0x4c/0x1bc
  [    2.994202]  mutex_unlock+0x44/0x50
  [    2.994210]  mt8186_afe_gpio_request+0xf8/0x210
  [    2.994220]  mt8186_afe_gpio_init+0xcc/0x134
  [    2.994230]  mt8186_mt6366_rt1019_rt5682s_dev_probe+0x14c/0x220
  [    2.994238]  platform_probe+0xb0/0xd0
  [    2.994247]  really_probe+0xcc/0x2c8
  [    2.994253]  __driver_probe_device+0xbc/0xe8
  [    2.994264]  driver_probe_device+0x48/0xf0
  [    2.994271]  __device_attach_driver+0xa0/0xc8
  [    2.994278]  bus_for_each_drv+0x8c/0xd8
  [    2.994288]  __device_attach+0xc4/0x150
  [    2.994298]  device_initial_probe+0x1c/0x28
  [    2.994308]  bus_probe_device+0x3c/0xa0
  [    2.994318]  deferred_probe_work_func+0xa0/0xe0
  [    2.994325]  process_one_work+0x208/0x364
  [    2.994334]  worker_thread+0x288/0x3fc
  [    2.994343]  kthread+0x140/0x160
  [    2.994351]  ret_from_fork+0x10/0x20

The cause is that the mutex will be double unlocked if dai is unknown
during GPIO selection, and this patch fixes it.

Fixes: cfa9a966f12a ("ASoC: mediatek: mt8186: support gpio control in platform driver")

Signed-off-by: Fei Shao <fshao@...omium.org>
---

 sound/soc/mediatek/mt8186/mt8186-afe-gpio.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/sound/soc/mediatek/mt8186/mt8186-afe-gpio.c b/sound/soc/mediatek/mt8186/mt8186-afe-gpio.c
index 255ffba637d3..274c0c8ec2f2 100644
--- a/sound/soc/mediatek/mt8186/mt8186-afe-gpio.c
+++ b/sound/soc/mediatek/mt8186/mt8186-afe-gpio.c
@@ -230,7 +230,6 @@ int mt8186_afe_gpio_request(struct device *dev, bool enable,
 		sel = enable ? MT8186_AFE_GPIO_PCM_ON : MT8186_AFE_GPIO_PCM_OFF;
 		break;
 	default:
-		mutex_unlock(&gpio_request_mutex);
 		dev_err(dev, "%s(), invalid dai %d\n", __func__, dai);
 		goto unlock;
 	}
-- 
2.36.1.476.g0c4daa206d-goog