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

[Kuninori Morimoto]

Hi Ranjani

Thank you for your feedback

> Thanks, Morimoto-san. I submitted a solution to fix the deadlock just a
> couple of days ago as well (
> https://mailman.alsa-project.org/pipermail/alsa-devel/2019-June/150764.html
> ). 
> 
> I am fine with either solution though.

Hmm... If my understanding was correct,
mutex_lock under snd_soc_unbind_card() is not good / not enough.
My patch can solve these, but please double check it.

# To be honest, current ALSA SoC is very difficult to read.
# Thus, I'm working to cleanup code, actually. I want to post it.
# I'm waiting for posted patches to be applied


1) snd_soc_unbind_card() is used from snd_soc_component_del_unlocked()
   which is used from __snd_soc_unregister_component().
   It is using mutex_lock() already

	__snd_soc_unregister_component()
=>		mutex_lock()
			snd_soc_component_del_unlocked()
				snd_soc_unbind_card()
=>					mutex_lock()
					soc_remove_link_components()
=>					mutex_unlock()
(*2)					soc_cleanup_card_resources()
=>		mutex_unlock()


(2) soc_cleanup_card_resources() also calls soc_remove_link_components()
    (see above (*2))

	soc_cleanup_card_resources()
		soc_remove_dai_links()
=>			soc_remove_link_components()