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Date: Tue, 16 Feb 2016 17:18:29 +0100
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From: Takashi Iwai <tiwai@suse.de>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arm-kernel@lists.infradead.org, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org, Jaroslav Kysela <perex@perex.cz>,
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        Libin Yang <libin.yang@linux.intel.com>,
        Thierry Reding <treding@nvidia.com>,
        David Henningsson <david.henningsson@canonical.com>
Subject: Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer
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On Tue, 16 Feb 2016 17:09:43 +0100,
Arnd Bergmann wrote:
> 
> On Tuesday 16 February 2016 16:49:42 Takashi Iwai wrote:
> > 
> > Thanks for the patch.  But I think it's cleaner to fix Kconfig.
> > 
> > Thinking more of it, maybe splitting jack stuff as a separate module
> > and does reverse-select to CONFIG_INPUT would be better.  Then its
> > users can select simply SND_JACK, and everything would fit.
> > 
> > 
> 
> Adding 'select INPUT' is rather nasty, I think that can lead to circular
> dependencies, and would likely upset users of small embedded systems
> that want to use audio but don't want to use input.

Fair enough.

> Generally speaking, I would recommend never using 'select' on a user
> visible Kconfig symbol.
>
> Another option might would be to change snd_jack_new() to return
> an error if that SND_JACK is disabled, and then require all users
> to handle the error gracefully, i.e. not fail the probe() function
> but just not use the jack.

Yes, I thought of that, too.  If select is no good option, it's a good
alternative, indeed.


Takashi