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@renesas.com
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@renesas.com
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