Re: [PATCH v2 00/11] getting back -Wmaybe-uninitialized

From: Linus Torvalds <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
To: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>,
	Srinivas Kandagatla
	<srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	sayli karnik
	<karniksayli1995-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Anna Schumaker
	<anna.schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org>,
	"David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>,
	Herbert Xu
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	Ilya Dryomov <idryomov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Javier Martinez Canillas
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	Ley Foon Tan <lftan-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org>,
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Subject: Re: [PATCH v2 00/11] getting back -Wmaybe-uninitialized
Date: Fri, 11 Nov 2016 09:13:00 -0800	[thread overview]
Message-ID: <CA+55aFx_scFVFKU__TBmoffw_iHvrdAU2dj5u1WKfWJXAkS4QA@mail.gmail.com> (raw)
In-Reply-To: <20161110164454.293477-1-arnd-r2nGTMty4D4@public.gmane.org>

On Thu, Nov 10, 2016 at 8:44 AM, Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org> wrote:
>
> Please merge these directly if you are happy with the result.

I will take this.

I do see two warnings, but they both seem to be valid and recent,
though, so I have no issues with the spurious cases.

Warning #1:

  sound/soc/qcom/lpass-platform.c: In function ‘lpass_platform_pcmops_open’:
  sound/soc/qcom/lpass-platform.c:83:29: warning: ‘dma_ch’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
    drvdata->substream[dma_ch] = substream;
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

and 'dma_ch' usage there really is crazy and wrong. Broken by
022d00ee0b55 ("ASoC: lpass-platform: Fix broken pcm data usage")

Warning #2 is not a real bug, but it's reasonable that gcc doesn't
know that storage_bytes (chip->read_size) has to be 2/4. Again,
introduced recently by commit 231147ee77f3 ("iio: maxim_thermocouple:
Align 16 bit big endian value of raw reads"), so you didn't see it.

  drivers/iio/temperature/maxim_thermocouple.c: In function
‘maxim_thermocouple_read_raw’:
  drivers/iio/temperature/maxim_thermocouple.c:141:5: warning: ‘ret’
may be used uninitialized in this function [-Wmaybe-uninitialized]
    if (ret)
       ^
  drivers/iio/temperature/maxim_thermocouple.c:128:6: note: ‘ret’ was
declared here
    int ret;
        ^~~

and I guess that code can just initialize 'ret' to '-EINVAL' or
something to just make the theoretical "somehow we had a wrong
chip->read_size" case error out cleanly.

                Linus
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