From: Jean Delvare <jdelvare@suse.de>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Anders Roxell <anders.roxell@linaro.org>,
linux-i2c <linux-i2c@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] i2c: i801: fix unused-function warning
Date: Tue, 15 May 2018 10:16:02 +0200 [thread overview]
Message-ID: <20180515101602.79ff49cf@endymion> (raw)
In-Reply-To: <CAHp75VdJEzDsvJmv812wvc5p=frqc3KU8HW=y4cGULYEp4=SKQ@mail.gmail.com>
Hi Andy,
On Mon, 14 May 2018 20:18:37 +0300, Andy Shevchenko wrote:
> On Mon, May 14, 2018 at 12:33 PM, Anders Roxell
> <anders.roxell@linaro.org> wrote:
> > With CONFIG_PM, we get a harmless build warning:
> > drivers/i2c/busses/i2c-i801.c:1723:12: warning: ‘i801_resume’ defined but not used [-Wunused-function]
> > static int i801_resume(struct device *dev)
> > ^~~~~~~~~~~
> > drivers/i2c/busses/i2c-i801.c:1714:12: warning: ‘i801_suspend’ defined but not used [-Wunused-function]
> > static int i801_suspend(struct device *dev)
> > ^~~~~~~~~~~~
>
> > -#ifdef CONFIG_PM
> > +#ifdef CONFIG_PM_SLEEP
> > static int i801_suspend(struct device *dev)
>
> The better pattern is to get rid of ugly ifdef and supply
> __maybe_unused annotation to each function in question.
That was Anders' first proposal, but it was declined by the driver
maintainer (me.) See:
https://marc.info/?l=linux-kernel&m=152588526520326&w=2
__maybe_unused is just a way to prevent the compiler from doing its
job. If it's really what you want, you might as well build with
-Wno-unused, instead of crippling the code with yet another annotation.
I can't see how building unused code only to discard it later can be
better than a proper #ifdef which will only build the code when we
actually need it.
Maybe there are cases where __maybe_unused is actually needed, but in
my opinion that should be the last resort option. That's not the case
here.
--
Jean Delvare
SUSE L3 Support
next prev parent reply other threads:[~2018-05-15 8:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-08 7:38 [PATCH] i2c: i801: mark PM functions as __maybe_unused Anders Roxell
2018-05-09 17:00 ` Jean Delvare
2018-05-10 13:27 ` Jean Delvare
2018-05-14 9:33 ` [PATCH v2] i2c: i801: fix unused-function warning Anders Roxell
2018-05-14 15:02 ` Jean Delvare
2018-05-14 17:18 ` Andy Shevchenko
2018-05-15 8:16 ` Jean Delvare [this message]
2018-05-17 13:54 ` Wolfram Sang
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