linux-kernel - Re: [PATCH] Regulator: Suppress compiler warnings

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Message-ID: <20150901130955.GV5313@sirena.org.uk>
Date:	Tue, 1 Sep 2015 14:09:55 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Keith Busch <keith.busch@...el.com>, linux-kernel@...r.kernel.org,
	Liam Girdwood <lgirdwood@...il.com>
Subject: Re: [PATCH] Regulator: Suppress compiler warnings

On Tue, Sep 01, 2015 at 09:52:13AM +0900, Krzysztof Kozlowski wrote:
> 2015-09-01 1:41 GMT+09:00 Keith Busch <keith.busch@...el.com>:
> > Some compilers complain of possible uninitialized variable usage, like
> > the following:

> >   drivers/regulator/helpers.c: In function ‘regulator_get_bypass_regmap’:
> >   drivers/regulator/helpers.c:463:16: warning: ‘val’ may be used uninitialized in this function [-Wuninitialized]

> > The code is safe though, and only uses the variables if they were
> > successfully set, so suppressing the warning with uninitialized_val.

> >  int regulator_is_enabled_regmap(struct regulator_dev *rdev)
> >  {
> > -       unsigned int val;
> > +       unsigned int uninitialized_var(val);
> >         int ret;
> >
> >         ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, &val);

> This is quite common pattern so such work-around should be added to
> many other functions leading to code obfuscation. Which compiler do
> you have in mind?

Right, plus this will shut up valid compiler warnings which is poor
practice anyway.  I'd say this is a bug in the compiler.

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