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

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Message-ID: <Ztlto06GyFxLXz1y@smile.fi.intel.com>
Date: Thu, 5 Sep 2024 11:36:51 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Hans de Goede <hdegoede@...hat.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Gergo Koteles <soyer@....hu>, platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org, Ike Panhc <ike.pan@...onical.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.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 Thu, Sep 05, 2024 at 10:33:22AM +0200, Hans de Goede wrote:
> On 9/4/24 10:18 PM, Andy Shevchenko wrote:
> > Wed, Sep 04, 2024 at 08:14:53PM +0200, Hans de Goede kirjoitti:
> >> On 8/29/24 6:50 PM, 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.
> >>>
> >>> That said, assign dummy value and make the scope_guard() clear of its scope.
> >>> For the sake of consistency do it in the entire file.
> >>>
> >>> Fixes: 7cc06e729460 ("platform/x86: ideapad-laptop: add a mutex to synchronize VPC commands")
> >>> Reported-by: kernel test robot <lkp@...el.com>
> >>> Closes: https://lore.kernel.org/oe-kbuild-all/202408290219.BrPO8twi-lkp@intel.com/
> >>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > 
> >> Thank you for your patch, I've applied this patch to my review-hans 
> >> branch:
> >> https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans
> > 
> > Have you had a chance to go through the discussion?
> 
> Yes I did read the entire discussion.
> 
> > TL;DR: please defer this. There is still no clear understanding of the root
> > cause and the culprit.
> 
> My gist from the discussion was that this was good to have regardless of
> the root cause.
> 
> IMHO the old construction where the scoped-guard only guards the function-call
> and not the "if (ret)" on the return value of the guarded call was quite ugly /
> convoluted / hard to read and this patch is an improvement regardless.

Okay, if you think it's good to go, you are welcome!

Thanks!

-- 
With Best Regards,
Andy Shevchenko