Hi Morimoto-san,
Other solution is create both snd_soc_find_dai_with_mutex()/without_mutex(). I'm not sure which style is best.
I don't know how complex it is to have a unified solution. But if we can protect snd_soc_find_dai() itself, things would be simpler may be in long term. Right now there are separate source files for soc-core, soc-dai and soc-component, but because of two approaches looks like the function need to be moved around and need to be placed in soc-core. Also the issue might go unnoticed if LOCKDEP is not enabled.
May be start with a wrapper for now and eventually unify?
Yeah, it seems has _with_mutex() can be better idea. I'm posting patch, but I noticed that Mark's branch vs Linus branch have some mismatch (?), and now I'm asking it to him. I can post _with_mutex() version as v2 if I could get answer. After that I'm happy your next patch can re-use it.
Sure. BTW, there are more such candidates which require 'lock' version of these helpers. For example: soc_find_component(), snd_soc_add/remove_pcm_runtime() and snd_soc_register_dai().
Thank you for the feedback.