linux-kernel - Re: [PATCH v1 1/1] sched/fair: Mark cfs_bandwidth_used() and m*_vruntime() with __maybe

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Message-ID: <xhsmh1pzgckh7.mognet@vschneid-thinkpadt14sgen2i.remote.csb>
Date: Tue, 12 Nov 2024 20:36:52 +0100
From: Valentin Schneider <vschneid@...hat.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
 llvm@...ts.linux.dev, Ingo Molnar <mingo@...hat.com>, Peter Zijlstra
 <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>, Vincent
 Guittot <vincent.guittot@...aro.org>, Dietmar Eggemann
 <dietmar.eggemann@....com>, Steven Rostedt <rostedt@...dmis.org>, Ben
 Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, Nathan
 Chancellor <nathan@...nel.org>, Nick Desaulniers
 <ndesaulniers@...gle.com>, Bill Wendling <morbo@...gle.com>, Justin Stitt
 <justinstitt@...gle.com>
Subject: Re: [PATCH v1 1/1] sched/fair: Mark cfs_bandwidth_used() and
 m*_vruntime() with __maybe_unused

On 12/11/24 17:18, Andy Shevchenko wrote:
> On Tue, Nov 12, 2024 at 12:48:42PM +0100, Valentin Schneider wrote:
>> On 05/09/24 20:12, Andy Shevchenko wrote:
>> > When cfs_bandwidth_used() is unused, it prevents kernel builds
>> > with clang, `make W=1` and CONFIG_WERROR=y:
>> >
>> > kernel/sched/fair.c:526:19: error: unused function 'max_vruntime' [-Werror,-Wunused-function]
>> >   526 | static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
>> >       |                   ^~~~~~~~~~~~
>> > kernel/sched/fair.c:6580:20: error: unused function 'cfs_bandwidth_used' [-Werror,-Wunused-function]
>> >  6580 | static inline bool cfs_bandwidth_used(void)
>> >       |                    ^~~~~~~~~~~~~~~~~~
>> >
>> > Fix this by marking them with __maybe_unused (all cases for the sake of
>> > symmetry).
>> >
>> 
>> I assume that's with CONFIG_CFS_BANDWIDTH=n? Looks like
>> cfs_bandwidth_used() uses are tucked away under helpers that themselves
>> only really do something for CONFIG_CFS_BANDWIDTH=y, so you could remove
>> the CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used() directly.
>
> Thanks for looking into this!
>
>> This compiles:
>
> okay, consider then my patch as a report. Can you submit your version as you
> seems much more familiar with this code than me?

Sure, I'll add this to my todolist.