[alsa-devel] [RFC][PATCH] ASoC: soc-core: verify Sound Card normality

[Kuninori Morimoto]

Current ALSA SoC Sound Card basically consists of CPU/Codec/Platform
components. If system uses Kernel modules, we can disable these drivers
by using rmmod command. In such case, we can't disable
CPU/Codec/Platform driver without disabling Sound Card driver.

But on the other hand, we can disable these drivers by using unbind
command. In such case, we can disable these drivers randomly.
In this case, we can create dirty Sound Card which is missing necessary
components.

(1) If user disabled Sound Card first, but did nothing to other drivers,
user can't use Sound because Sound Card is no longer exists.
(2) If user disabled CPU/Codec/Platform driver randomly, but did nothing
to Sound Card, user still be able to use Sound Card, because dirty Sound
Card still exists. In this case, Sound system will be crashed if user
started sound playback/capture. But we can't block such random unbind
now.

To avoid Sound Card crash in (2) case, we need to unregister Sound Card
whenever CPU/Codec/Platform component were unregistered.
This patch solves this issue.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx at renesas.com>
---
 sound/soc/soc-core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 07e4eec..52760bd 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -3236,6 +3236,11 @@ static void snd_soc_component_cleanup(struct snd_soc_component *component)
 
 static void snd_soc_component_del_unlocked(struct snd_soc_component *component)
 {
+	struct snd_soc_card *card = component->card;
+
+	if (card)
+		snd_soc_unregister_card(card);
+
 	list_del(&component->list);
 }
 
-- 
1.9.1