Commit 62d5ae4cafb7 ("ASoC: max98090: save and restore SHDN when changing sensitive registers") extended the code for handling many controls by adding a custom put function to them. That new custom put function properly handles relations between codec's hardware registers. However they used card->dapm_mutex to properly serialize those operations. This in turn triggers a lockdep warning about possible circular dependency. Fix this by introducing a separate mutex only for serializing the SHDN hardware register related operations.
This fixes the following lockdep warning observed on Exynos4412-based Odroid U3 board: ====================================================== WARNING: possible circular locking dependency detected 5.5.0-rc5-next-20200107 #166 Not tainted ------------------------------------------------------ alsactl/1104 is trying to acquire lock: ed0d50f4 (&card->dapm_mutex){+.+.}, at: max98090_shdn_save+0x1c/0x28
but task is already holding lock: edb4b49c (&card->controls_rwsem){++++}, at: snd_ctl_ioctl+0xcc/0xbb8
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&card->controls_rwsem){++++}: snd_ctl_add_replace+0x3c/0x84 dapm_create_or_share_kcontrol+0x24c/0x2e0 snd_soc_dapm_new_widgets+0x308/0x594 snd_soc_bind_card+0x80c/0xad4 devm_snd_soc_register_card+0x34/0x6c odroid_audio_probe+0x288/0x34c platform_drv_probe+0x6c/0xa4 really_probe+0x200/0x490 driver_probe_device+0x78/0x1f8 bus_for_each_drv+0x74/0xb8 __device_attach+0xd4/0x16c bus_probe_device+0x88/0x90 deferred_probe_work_func+0x3c/0xd0 process_one_work+0x22c/0x7c4 worker_thread+0x44/0x524 kthread+0x130/0x164 ret_from_fork+0x14/0x20 0x0
-> #0 (&card->dapm_mutex){+.+.}: lock_acquire+0xe8/0x270 __mutex_lock+0x9c/0xb18 mutex_lock_nested+0x1c/0x24 max98090_shdn_save+0x1c/0x28 max98090_put_enum_double+0x20/0x40 snd_ctl_ioctl+0x190/0xbb8 ksys_ioctl+0x470/0xaf8 ret_fast_syscall+0x0/0x28 0xbefaa564
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&card->controls_rwsem); lock(&card->dapm_mutex); lock(&card->controls_rwsem); lock(&card->dapm_mutex);
*** DEADLOCK ***
1 lock held by alsactl/1104: #0: edb4b49c (&card->controls_rwsem){++++}, at: snd_ctl_ioctl+0xcc/0xbb8
stack backtrace: CPU: 0 PID: 1104 Comm: alsactl Not tainted 5.5.0-rc5-next-20200107 #166 Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) (unwind_backtrace) from [<c010e180>] (show_stack+0x10/0x14) (show_stack) from [<c0b2a09c>] (dump_stack+0xb4/0xe0) (dump_stack) from [<c018a1c0>] (check_noncircular+0x1ec/0x208) (check_noncircular) from [<c018c5dc>] (__lock_acquire+0x1210/0x25ec) (__lock_acquire) from [<c018e2d8>] (lock_acquire+0xe8/0x270) (lock_acquire) from [<c0b49678>] (__mutex_lock+0x9c/0xb18) (__mutex_lock) from [<c0b4a110>] (mutex_lock_nested+0x1c/0x24) (mutex_lock_nested) from [<c0839b3c>] (max98090_shdn_save+0x1c/0x28) (max98090_shdn_save) from [<c083a5b8>] (max98090_put_enum_double+0x20/0x40) (max98090_put_enum_double) from [<c080d0e8>] (snd_ctl_ioctl+0x190/0xbb8) (snd_ctl_ioctl) from [<c02cafec>] (ksys_ioctl+0x470/0xaf8) (ksys_ioctl) from [<c0101000>] (ret_fast_syscall+0x0/0x28) ...
Fixes: 62d5ae4cafb7 ("ASoC: max98090: save and restore SHDN when changing sensitive registers") Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com --- sound/soc/codecs/max98090.c | 10 ++++++---- sound/soc/codecs/max98090.h | 1 + 2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/sound/soc/codecs/max98090.c b/sound/soc/codecs/max98090.c index c01ce4a3f86d..454cb8e5b0a1 100644 --- a/sound/soc/codecs/max98090.c +++ b/sound/soc/codecs/max98090.c @@ -52,14 +52,14 @@ static void max98090_shdn_restore_locked(struct max98090_priv *max98090)
static void max98090_shdn_save(struct max98090_priv *max98090) { - mutex_lock(&max98090->component->card->dapm_mutex); + mutex_lock(&max98090->shdn_lock); max98090_shdn_save_locked(max98090); }
static void max98090_shdn_restore(struct max98090_priv *max98090) { max98090_shdn_restore_locked(max98090); - mutex_unlock(&max98090->component->card->dapm_mutex); + mutex_unlock(&max98090->shdn_lock); }
static int max98090_put_volsw(struct snd_kcontrol *kcontrol, @@ -2313,12 +2313,12 @@ static void max98090_pll_work(struct max98090_priv *max98090) */
/* Toggle shutdown OFF then ON */ - mutex_lock(&component->card->dapm_mutex); + mutex_lock(&max98090->shdn_lock); snd_soc_component_update_bits(component, M98090_REG_DEVICE_SHUTDOWN, M98090_SHDNN_MASK, 0); snd_soc_component_update_bits(component, M98090_REG_DEVICE_SHUTDOWN, M98090_SHDNN_MASK, M98090_SHDNN_MASK); - mutex_unlock(&component->card->dapm_mutex); + mutex_unlock(&max98090->shdn_lock);
for (i = 0; i < 10; ++i) { /* Give PLL time to lock */ @@ -2731,6 +2731,8 @@ static int max98090_i2c_probe(struct i2c_client *i2c, if (max98090 == NULL) return -ENOMEM;
+ mutex_init(&max98090->shdn_lock); + if (ACPI_HANDLE(&i2c->dev)) { acpi_id = acpi_match_device(i2c->dev.driver->acpi_match_table, &i2c->dev); diff --git a/sound/soc/codecs/max98090.h b/sound/soc/codecs/max98090.h index 0a31708b7df7..dabd8be34a01 100644 --- a/sound/soc/codecs/max98090.h +++ b/sound/soc/codecs/max98090.h @@ -1539,6 +1539,7 @@ struct max98090_priv { unsigned int pa2en; unsigned int sidetone; bool master; + struct mutex shdn_lock; int saved_count; int saved_shdn; };