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

[Takashi Iwai <tiwai@suse.de>]

On Mon, 03 Apr 2017 10:26:05 +0200,
Kuninori Morimoto wrote:
> 
> 
> Hi Takashi-san
> 
> > > So, we can call snd_soc_unregister_card() whenever CPU/Codec/Platform
> > > were unregsiterd.
> > 
> > In theory yes, but you should be careful to do so, e.g. make sure that
> > it won't be called again by the removal/unbind of other components /
> > drivers.
> > 
> > I suggested snd_card_disconnect() because it doesn't release resources
> > by itself, but it just disconnects from the further accesses.  So,
> > double-free won't happen in this case.  It makes the hotunplug safer
> > as long as the drivers manage the resource releases properly.
> 
> I had checked many unbind/bind pattern/order on 2nd [RFC] patch which I posted.
> At first, I believe Oops on unbind/bind issue was solved on it.
> 2nd, if my understanding was correct, it doesn't have double-free issue,
> or something like that.
> But, I'm not 100% sure about 2nd, thus it has [RFC] on patch.

Ah, I see that snd_soc_unregister_card() has the check of
card->instantiated, so it should be fine to call multiple times.


thanks,

Takashi