Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200818170337.805624-1-alex.dewar90@gmail.com>
 <CAKwvOdk2fynn=-FGUniYLG+hCOkEFppRnAaTYe8DW=YRrT-siQ@mail.gmail.com> <20200818195746.scpjm3dlg7cfst53@medion>
In-Reply-To: <20200818195746.scpjm3dlg7cfst53@medion>
From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 18 Aug 2020 13:02:26 -0700
Message-ID: <CAKwvOdn=32A4QumC_-Y8fJ29fqUPzPK0H_7-dn6rcsAT+O1xOw@mail.gmail.com>
Subject: Re: [PATCH] sched/cputime: Mark function as __maybe_unused
To:     Alex Dewar <alex.dewar90@gmail.com>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Aug 18, 2020 at 12:57 PM Alex Dewar <alex.dewar90@gmail.com> wrote:
>
> On Tue, Aug 18, 2020 at 11:13:10AM -0700, Nick Desaulniers wrote:
> > On Tue, Aug 18, 2020 at 10:04 AM Alex Dewar <alex.dewar90@gmail.com> wrote:
> > >
> > > Depending on config options, account_other_time() may not be called
> > > anywhere. Add __maybe_unused flag to fix clang warning.
> >
> > Just curious, would moving this definition to be within an existing
> > preprocessor guard for a particular config also fix the issue? If so,
> > prefer that. If not, __maybe_unused is the way to go.
>
> I don't think that'd work here: it's used within an "#ifdef
> CONFIG_IRQ_TIME_ACCOUNTING" block and a separate "#ifdef
> CONFIG_VIRT_CPU_ACCOUNTING_GEN" one. We could do:
>         #if defined(CONFIG_IRQ_TIME_ACCOUNTING) ||
>             defined(CONFIG_VIRT_CPU_ACCOUNTING)
>                 ...
> ... but that might be a bit ugly.

Yeah, ok, in that case it's fine.  One issue with __maybe_unused is
that this function will stick around forever if all call sites get
removed.  But when the preprocessor checks start getting hairy,
__maybe_unused is maybe simpler.
Acked-by: Nick Desaulniers <ndesaulniers@google.com>

>
> >
> > >
> > > Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
> > > ---
> > >  kernel/sched/cputime.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> > > index 5a55d2300452..43ede0d6661c 100644
> > > --- a/kernel/sched/cputime.c
> > > +++ b/kernel/sched/cputime.c
> > > @@ -252,7 +252,7 @@ static __always_inline u64 steal_account_process_time(u64 maxtime)
> > >  /*
> > >   * Account how much elapsed time was spent in steal, irq, or softirq time.
> > >   */
> > > -static inline u64 account_other_time(u64 max)
> > > +static inline u64 __maybe_unused account_other_time(u64 max)
> > >  {
> > >         u64 accounted;
> > >
> > > --
> > > 2.28.0
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20200818170337.805624-1-alex.dewar90%40gmail.com.
> >
> >
> >
> > --
> > Thanks,
> > ~Nick Desaulniers


-- 
Thanks,
~Nick Desaulniers