linux-kernel - Re: [PATCH v3] eeepc-laptop: simplify parse

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Message-ID: <20140917213934.GC4432@gmail.com>
Date:	Wed, 17 Sep 2014 23:39:34 +0200
From:	Frans Klaver <fransklaver@...il.com>
To:	Darren Hart <dvhart@...radead.org>
Cc:	Paul Bolle <pebolle@...cali.nl>,
	Corentin Chary <corentin.chary@...il.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Rafael Wysocki <rafael.j.wysocki@...el.com>,
	acpi4asus-user@...ts.sourceforge.net,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] eeepc-laptop: simplify parse_arg()

On Wed, Sep 17, 2014 at 01:35:10PM -0700, Darren Hart wrote:
> On Wed, Sep 17, 2014 at 09:02:51PM +0200, Paul Bolle wrote:
> > parse_arg() has three possible return values:
> >     -EINVAL if sscanf(), in short, fails;
> >     zero if "count" is zero; and
> >     "count" in all other cases
> > 
> > But "count" will never be zero. See, parse_arg() is called by the
> > various store functions. And the callchain of these functions starts
> > with sysfs_kf_write(). And that function checks for a zero "count". So
> > we can stop checking for a zero "count", drop the "count" argument
> > entirely, and transform parse_arg() into a function that returns zero on
> > success or a negative error. That, in turn, allows to make those store
> > functions just return "count" on success. The net effect is that the
> > code becomes a bit easier to understand.
> > 
> > A nice side effect is that this GCC warning is silenced too:
> >     drivers/platform/x86/eeepc-laptop.c: In function ‘store_sys_acpi’:
> >     drivers/platform/x86/eeepc-laptop.c:279:10: warning: ‘value’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> >       int rv, value;
> > 
> > Which is, of course, the reason to have a look at parse_arg().
> > 
> > Signed-off-by: Paul Bolle <pebolle@...cali.nl>
> > ---
> > Still build tested only, but now on top of v3.17-rc5. Has Frans tested
> > writing zero length values to these sysfs files?
> 
> Frans, can you confirm testing when you get a chance please?

Tested. Looks OK to me.

Frans
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