Re: [PATCH] sched/cputime: Mark function as __maybe_unused

From: Nick Desaulniers
Date: Tue Aug 18 2020 - 16:02:40 EST


On Tue, Aug 18, 2020 at 12:57 PM Alex Dewar <alex.dewar90@xxxxxxxxx> 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@xxxxxxxxx> 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@xxxxxxxxxx>

>
> >
> > >
> > > Signed-off-by: Alex Dewar <alex.dewar90@xxxxxxxxx>
> > > ---
> > > 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
> > >
> > > --
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> >
> >
> >
> > --
> > Thanks,
> > ~Nick Desaulniers



--
Thanks,
~Nick Desaulniers