linux-kernel - Re: [PATCH v1 1/1] platform/x86: ideapad-laptop: Make the scope

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Message-ID: <Ztg1wzHB-so2qV2L@smile.fi.intel.com>
Date: Wed, 4 Sep 2024 13:26:11 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Gergo Koteles <soyer@....hu>, Hans de Goede <hdegoede@...hat.com>,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	Ike Panhc <ike.pan@...onical.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Nathan Chancellor <nathan@...nel.org>,
	kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v1 1/1] platform/x86: ideapad-laptop: Make the
 scope_guard() clear of its scope

On Tue, Sep 03, 2024 at 09:52:01PM -0700, Josh Poimboeuf wrote:
> On Thu, Aug 29, 2024 at 07:50:32PM +0300, Andy Shevchenko wrote:
> > First of all, it's a bit counterintuitive to have something like
> > 
> > 	int err;
> > 	...
> > 	scoped_guard(...)
> > 		err = foo(...);
> > 	if (err)
> > 		return err;
> > 
> > Second, with a particular kernel configuration and compiler version in
> > one of such cases the objtool is not happy:
> > 
> >   ideapad-laptop.o: warning: objtool: .text.fan_mode_show: unexpected end of section
> >
> > I'm not an expert on all this, but the theory is that compiler and
> > linker in this case can't understand that 'result' variable will be
> > always initialized as long as no error has been returned. Assigning
> > 'result' to a dummy value helps with this. Note, that fixing the
> > scoped_guard() scope (as per above) does not make issue gone.
> 
> I'm not sure I buy that, we should look closer to understand what the
> issue is.  Can you share the config and/or toolchain version(s) need to
> trigger the warning?

.config is from the original report [1], toolchain is
Debian clang version 18.1.8 (9)
	Target: x86_64-pc-linux-gnu
	Thread model: posix
	InstalledDir: /usr/bin

(Just whatever Debian unstable provides)

[1]: https://lore.kernel.org/oe-kbuild-all/202408290219.BrPO8twi-lkp@intel.com/

-- 
With Best Regards,
Andy Shevchenko