linux-kernel - Re: [PATCH v7 3/8] powerpc/smp: Export cpu_coregroup

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Message-ID: <1c8392b8-ea7b-48ef-8932-02f41e1233a3@csgroup.eu>
Date: Tue, 26 Aug 2025 06:54:29 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: K Prateek Nayak <kprateek.nayak@....com>,
 Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
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Cc: Dietmar Eggemann <dietmar.eggemann@....com>,
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 Vinicius Costa Gomes <vinicius.gomes@...el.com>
Subject: Re: [PATCH v7 3/8] powerpc/smp: Export cpu_coregroup_mask()

Le 26/08/2025 à 06:13, K Prateek Nayak a écrit :
> Deine cpu_coregroup_mask() to export the per-cpu cpu_corgrp_map when
> coregroups are supported(). When has_coregroup_support() returns false,
> cpu_coregroup_mask() returns the mask used by the PKG domain.
> 
> Since this will only be used after CONFIG_SCHED_MC is added for PowerPC,
> no functional changes are intended at this point.
> 
> Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
> ---
>   arch/powerpc/include/asm/smp.h | 2 ++
>   arch/powerpc/kernel/smp.c      | 8 ++++++++
>   2 files changed, 10 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
> index b77927ccb0ab..86de4d0dd0aa 100644
> --- a/arch/powerpc/include/asm/smp.h
> +++ b/arch/powerpc/include/asm/smp.h
> @@ -148,6 +148,8 @@ static inline const struct cpumask *cpu_smt_mask(int cpu)
>   }
>   #endif /* CONFIG_SCHED_SMT */
>   
> +extern const struct cpumask *cpu_coregroup_mask(int cpu);

'extern' keyword is pointless for function prototypes, remove it.

See report from checkpatch:

$ ./scripts/checkpatch.pl --strict -g a064a30c52a5
CHECK: extern prototypes should be avoided in .h files
#28: FILE: arch/powerpc/include/asm/smp.h:151:
+extern const struct cpumask *cpu_coregroup_mask(int cpu);

total: 0 errors, 0 warnings, 1 checks, 22 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
       mechanically convert to the typical style using --fix or 
--fix-inplace.

Commit a064a30c52a5 ("powerpc/smp: Export cpu_coregroup_mask()") has 
style problems, please review.

NOTE: If any of the errors are false positives, please report
       them to the maintainer, see CHECKPATCH in MAINTAINERS.

> +
>   /* Since OpenPIC has only 4 IPIs, we use slightly different message numbers.
>    *
>    * Make sure this matches openpic_request_IPIs in open_pic.c, or what shows up
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 4f48262658cc..e623f2864dc4 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -1059,6 +1059,14 @@ static bool has_coregroup_support(void)
>   	return coregroup_enabled;
>   }
>   
> +const struct cpumask *cpu_coregroup_mask(int cpu)
> +{
> +	if (has_coregroup_support())
> +		return per_cpu(cpu_corgrp_map, cpu);
> +
> +	return cpu_node_mask(cpu);
> +}
> +
>   static const struct cpumask *cpu_mc_mask(struct sched_domain_topology_level *tl, int cpu)
>   {
>   	return cpu_corgrp_mask(cpu);