Hi Ranjani
Can you please confirm this patch ?
It is no problem if I unbind "sound card" 1st,
but, have issue if I unbind "CPU driver" 1st.
-----------------------
# echo ec500000.sound > /sys/bus/platform/drivers/rcar_sound/unbind
[ 29.972081]
[ 29.973581] ============================================
[ 29.978891] WARNING: possible recursive locking detected
[ 29.984203] 5.2.0-rc5+ #312 Not tainted
[ 29.988036] --------------------------------------------
[ 29.993346] sh/190 is trying to acquire lock:
[ 29.997700] (____ptrval____) (client_mutex){+.+.}, at: snd_soc_unbind_card.part.9+0x78/0xf8
[ 30.006070]
[ 30.006070] but task is already holding lock:
[ 30.011901] (____ptrval____) (client_mutex){+.+.}, at: snd_soc_unregister_component+0x54/0xe8
[ 30.020432]
[ 30.020432] other info that might help us debug this:
[ 30.026959] Possible unsafe locking scenario:
[ 30.026959]
[ 30.032876] CPU0
[ 30.035318] ----
[ 30.037759] lock(client_mutex);
[ 30.041071] lock(client_mutex);
[ 30.044383]
[ 30.044383] *** DEADLOCK ***
[ 30.044383]
[ 30.050301] May be due to missing lock nesting notation
[ 30.050301]
[ 30.057088] 4 locks held by sh/190:
[ 30.060572] #0: (____ptrval____) (sb_writers#6){.+.+}, at: vfs_write+0x198/0x1b8
[ 30.068063] #1: (____ptrval____) (&of->mutex){+.+.}, at: kernfs_fop_write+0xc0/0x1e8
[ 30.075900] #2: (____ptrval____) (&dev->mutex){....}, at: __device_driver_lock+0x38/0x68
[ 30.084085] #3: (____ptrval____) (client_mutex){+.+.}, at: snd_soc_unregister_component+0x54/0xe8
[ 30.093049]
[ 30.093049] stack backtrace:
[ 30.097406] CPU: 2 PID: 190 Comm: sh Not tainted 5.2.0-rc5+ #312
[ 30.103411] Hardware name: Renesas H3ULCB Kingfisher board based on r8a7795 ES2.0+ (DT)
[ 30.111414] Call trace:
[ 30.113860] dump_backtrace+0x0/0x140
[ 30.117520] show_stack+0x24/0x30
[ 30.120837] dump_stack+0xc8/0x114
[ 30.124238] __lock_acquire+0x1de4/0x1e48
[ 30.128244] lock_acquire+0xdc/0x258
[ 30.131819] __mutex_lock+0x80/0x7c8
[ 30.135392] mutex_lock_nested+0x3c/0x50
[ 30.139312] snd_soc_unbind_card.part.9+0x78/0xf8
[ 30.144015] snd_soc_unregister_component+0xe4/0xe8
[ 30.148894] devm_component_release+0x20/0x30
[ 30.153250] release_nodes+0x1c8/0x240
[ 30.156996] devres_release_all+0x3c/0x58
[ 30.161004] device_release_driver_internal+0x100/0x1c0
[ 30.166226] device_driver_detach+0x28/0x38
[ 30.170407] unbind_store+0x94/0x100
[ 30.173979] drv_attr_store+0x40/0x58
[ 30.177640] sysfs_kf_write+0x50/0x78
[ 30.181299] kernfs_fop_write+0xf0/0x1e8
[ 30.185219] __vfs_write+0x48/0x90
[ 30.188617] vfs_write+0xac/0x1b8
[ 30.191928] ksys_write+0x74/0xf8
[ 30.195240] __arm64_sys_write+0x24/0x30
[ 30.199163] el0_svc_common.constprop.0+0x98/0x170
[ 30.203952] el0_svc_compat_handler+0x2c/0x38
[ 30.208307] el0_svc_compat+0x8/0x10
-----------------------
> From: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
>
> commit 34ac3c3eb8f0c07 ("ASoC: core: lock client_mutex while removing
> link components") added mutex_lock() at soc_remove_link_components().
>
> Is is called from snd_soc_unbind_card()
>
> snd_soc_unbind_card()
> => soc_remove_link_components()
> soc_cleanup_card_resources()
> soc_remove_dai_links()
> => soc_remove_link_components()
>
> And, there are 2 way to call it.
>
> (1)
> snd_soc_unregister_component()
> ** mutex_lock()
> snd_soc_component_del_unlocked()
> => snd_soc_unbind_card()
> ** mutex_unlock()
>
> (2)
> snd_soc_unregister_card()
> => snd_soc_unbind_card()
>
> (1) case is already using mutex_lock() when it calles
> snd_soc_unbind_card(), thus, we will get lockdep warning.
>
> commit 495f926c68ddb90 ("ASoC: core: Fix deadlock in
> snd_soc_instantiate_card()") tried to fixup it, but still not
> enough. We still have lockdep warning when we try unbind/bind.
>
> We need mutex_lock() under snd_soc_unregister_card()
> instead of snd_remove_link_components()/snd_soc_unbind_card().
>
> Fixes: 34ac3c3eb8f0c07 ("ASoC: core: lock client_mutex while removing link components")
> Fixes: 495f926c68ddb90 ("ASoC: core: Fix deadlock in snd_soc_instantiate_card()")
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> ---
> sound/soc/soc-core.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
> index 2353886..2a408cc 100644
> --- a/sound/soc/soc-core.c
> +++ b/sound/soc/soc-core.c
> @@ -2747,14 +2747,12 @@ static void snd_soc_unbind_card(struct snd_soc_card *card, bool unregister)
> snd_soc_dapm_shutdown(card);
> snd_soc_flush_all_delayed_work(card);
>
> - mutex_lock(&client_mutex);
> /* remove all components used by DAI links on this card */
> for_each_comp_order(order) {
> for_each_card_rtds(card, rtd) {
> soc_remove_link_components(card, rtd, order);
> }
> }
> - mutex_unlock(&client_mutex);
>
> soc_cleanup_card_resources(card);
> if (!unregister)
> @@ -2773,7 +2771,9 @@ static void snd_soc_unbind_card(struct snd_soc_card *card, bool unregister)
> */
> int snd_soc_unregister_card(struct snd_soc_card *card)
> {
> + mutex_lock(&client_mutex);
> snd_soc_unbind_card(card, true);
> + mutex_unlock(&client_mutex);
> dev_dbg(card->dev, "ASoC: Unregistered card '%s'\n", card->name);
>
> return 0;
> --
> 2.7.4
>
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