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    Subject[PATCH v2 2/5] smp: add set_nr_cpu_ids()
    Date
    In preparation to support compile-time nr_cpu_ids, add a setter for
    the variable.

    This is a no-op for all arches.

    Signed-off-by: Yury Norov <yury.norov@gmail.com>
    ---
    arch/loongarch/kernel/setup.c | 2 +-
    arch/mips/kernel/setup.c | 2 +-
    arch/x86/kernel/smpboot.c | 4 ++--
    arch/x86/xen/smp_pv.c | 2 +-
    include/linux/cpumask.h | 5 +++++
    kernel/smp.c | 4 ++--
    6 files changed, 12 insertions(+), 7 deletions(-)

    diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
    index 8f5c2f9a1a83..18a81edd3ac5 100644
    --- a/arch/loongarch/kernel/setup.c
    +++ b/arch/loongarch/kernel/setup.c
    @@ -346,7 +346,7 @@ static void __init prefill_possible_map(void)
    for (; i < NR_CPUS; i++)
    set_cpu_possible(i, false);

    - nr_cpu_ids = possible;
    + set_nr_cpu_ids(possible);
    }
    #endif

    diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
    index 2ca156a5b231..e8a0759cb4d0 100644
    --- a/arch/mips/kernel/setup.c
    +++ b/arch/mips/kernel/setup.c
    @@ -750,7 +750,7 @@ static void __init prefill_possible_map(void)
    for (; i < NR_CPUS; i++)
    set_cpu_possible(i, false);

    - nr_cpu_ids = possible;
    + set_nr_cpu_ids(possible);
    }
    #else
    static inline void prefill_possible_map(void) {}
    diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
    index f24227bc3220..3f3ea0287f69 100644
    --- a/arch/x86/kernel/smpboot.c
    +++ b/arch/x86/kernel/smpboot.c
    @@ -1316,7 +1316,7 @@ static void __init smp_sanity_check(void)
    nr++;
    }

    - nr_cpu_ids = 8;
    + set_nr_cpu_ids(8);
    }
    #endif

    @@ -1569,7 +1569,7 @@ __init void prefill_possible_map(void)
    possible = i;
    }

    - nr_cpu_ids = possible;
    + set_nr_cpu_ids(possible);

    pr_info("Allowing %d CPUs, %d hotplug CPUs\n",
    possible, max_t(int, possible - num_processors, 0));
    diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
    index ba7af2eca755..480be82e9b7b 100644
    --- a/arch/x86/xen/smp_pv.c
    +++ b/arch/x86/xen/smp_pv.c
    @@ -179,7 +179,7 @@ static void __init _get_smp_config(unsigned int early)
    * hypercall to expand the max number of VCPUs an already
    * running guest has. So cap it up to X. */
    if (subtract)
    - nr_cpu_ids = nr_cpu_ids - subtract;
    + set_nr_cpu_ids(nr_cpu_ids - subtract);
    #endif

    }
    diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
    index bd047864c7ac..0588bfe350d4 100644
    --- a/include/linux/cpumask.h
    +++ b/include/linux/cpumask.h
    @@ -39,6 +39,11 @@ typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
    #define nr_cpu_ids 1U
    #else
    extern unsigned int nr_cpu_ids;
    +
    +static inline void set_nr_cpu_ids(unsigned int nr)
    +{
    + nr_cpu_ids = nr;
    +}
    #endif

    #ifdef CONFIG_CPUMASK_OFFSTACK
    diff --git a/kernel/smp.c b/kernel/smp.c
    index e971c9626a1b..150310a0947a 100644
    --- a/kernel/smp.c
    +++ b/kernel/smp.c
    @@ -1070,7 +1070,7 @@ static int __init nrcpus(char *str)
    int nr_cpus;

    if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
    - nr_cpu_ids = nr_cpus;
    + set_nr_cpu_ids(nr_cpus);

    return 0;
    }
    @@ -1097,7 +1097,7 @@ EXPORT_SYMBOL(nr_cpu_ids);
    /* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */
    void __init setup_nr_cpu_ids(void)
    {
    - nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1;
    + set_nr_cpu_ids(find_last_bit(cpumask_bits(cpu_possible_mask), NR_CPUS) + 1);
    }

    /* Called by boot processor to activate the rest. */
    --
    2.34.1
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