[alsa-devel] [PATCH] ASoC: soc-core: call snd_soc_unbind_card() under mutex_lock;

[Kuninori Morimoto]

From: Kuninori Morimoto <kuninori.morimoto.gx at 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 at 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