linux-kernel - Re: [PATCH v7 5/8] sched/topology: Unify tl_smt

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Message-ID: <20250826082404.GF3245006@noisy.programming.kicks-ass.net>
Date: Tue, 26 Aug 2025 10:24:04 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Christophe Leroy <christophe.leroy@...roup.eu>
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Subject: Re: [PATCH v7 5/8] sched/topology: Unify tl_smt_mask() across core
 and all arch

On Tue, Aug 26, 2025 at 10:11:40AM +0200, Christophe Leroy wrote:
> 
> 
> Le 26/08/2025 à 10:01, Peter Zijlstra a écrit :
> > > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
> > > index 602508130c8a..d75fbb7d9667 100644
> > > --- a/include/linux/sched/topology.h
> > > +++ b/include/linux/sched/topology.h
> > > @@ -37,7 +37,13 @@ static inline int cpu_smt_flags(void)
> > >   {
> > >   	return SD_SHARE_CPUCAPACITY | SD_SHARE_LLC;
> > >   }
> > > -#endif
> > > +
> > > +static const __maybe_unused
> > > +struct cpumask *tl_smt_mask(struct sched_domain_topology_level *tl, int cpu)
> > > +{
> > > +	return cpu_smt_mask(cpu);
> > > +}
> > > +#endif /* CONFIG_SCHED_SMT */
> > 
> > Problem with that __maybe_unused is that you forgot inline.
> > 
> > static inline const
> > struct cpumask *tl_smt_mask(struct sched_domain_topology_level *tl, int cpu)
> > {
> > 	return cpu_smt_mask(cpu);
> > }
> > 
> > seems to make it happy.
> > 
> 
> But the function is referenced by SDTL_INIT() macro so there is no real
> point in declaring it inline. Would be cleaner to have it defined in a C
> file.

Ah, that's what you mean. I was more focussed on getting rid of that
horrible __maybe_unused and then either works. But yes, perhaps just
having them in a .c file is best.