Commit 08df0d9a00f7 ("ASoC: max98090: revert "ASoC: max98090: fix lockdep warning"") provided a good rationale for removing separate lock for the SHDN register access. However it restored the lockdep warning during the system boot. To silence the lockdep warning, mark the mutex taken in the max98090_shdn_save() function with the lockdep class dedicated for the runtime DAPM operations: SND_SOC_DAPM_CLASS_RUNTIME. This finally fixes the following lockdep warning observed on Exynos4412-based Odroid U3 board:

====================================================== WARNING: possible circular locking dependency detected 5.5.0-rc7-next-20200123 #7329 Not tainted ------------------------------------------------------ alsactl/1105 is trying to acquire lock: ed4f7cf4 (&card->dapm_mutex){+.+.}, at: max98090_shdn_save+0x1c/0x28

but task is already holding lock: edb8d49c (&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+0x834/0xa94 devm_snd_soc_register_card+0x34/0x6c odroid_audio_probe+0x288/0x34c platform_drv_probe+0x6c/0xa4 really_probe+0x200/0x48c 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+0x230/0x7bc 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+0x484/0xb10 ret_fast_syscall+0x0/0x28 0xbede0564

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/1105: #0: edb8d49c (&card->controls_rwsem){++++}, at: snd_ctl_ioctl+0xcc/0xbb8

stack backtrace: CPU: 2 PID: 1105 Comm: alsactl Not tainted 5.5.0-rc7-next-20200123 #7329 Hardware name: Samsung Exynos (Flattened Device Tree) [<c01126f0>] (unwind_backtrace) from [<c010e1e8>] (show_stack+0x10/0x14) [<c010e1e8>] (show_stack) from [<c0b5234c>] (dump_stack+0xb4/0xe0) [<c0b5234c>] (dump_stack) from [<c018a610>] (check_noncircular+0x1ec/0x208) [<c018a610>] (check_noncircular) from [<c018ca2c>] (__lock_acquire+0x1210/0x25ec) [<c018ca2c>] (__lock_acquire) from [<c018e728>] (lock_acquire+0xe8/0x270) [<c018e728>] (lock_acquire) from [<c0b71928>] (__mutex_lock+0x9c/0xb18) [<c0b71928>] (__mutex_lock) from [<c0b723c0>] (mutex_lock_nested+0x1c/0x24) [<c0b723c0>] (mutex_lock_nested) from [<c086097c>] (max98090_shdn_save+0x1c/0x28) [<c086097c>] (max98090_shdn_save) from [<c08613f8>] (max98090_put_enum_double+0x20/0x40) [<c08613f8>] (max98090_put_enum_double) from [<c0833f20>] (snd_ctl_ioctl+0x190/0xbb8) [<c0833f20>] (snd_ctl_ioctl) from [<c02cae14>] (ksys_ioctl+0x484/0xb10) [<c02cae14>] (ksys_ioctl) from [<c0101000>] (ret_fast_syscall+0x0/0x28) Exception stack(0xed331fa8 to 0xed331ff0) ...

Fixes: 08df0d9a00f7 ("ASoC: max98090: revert "ASoC: max98090: fix lockdep warning"") Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com --- sound/soc/codecs/max98090.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/max98090.c b/sound/soc/codecs/max98090.c index 0313e1183167..5bc2c6411b33 100644 --- a/sound/soc/codecs/max98090.c +++ b/sound/soc/codecs/max98090.c @@ -52,7 +52,8 @@ 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_nested(&max98090->component->card->dapm_mutex, + SND_SOC_DAPM_CLASS_RUNTIME); max98090_shdn_save_locked(max98090); }