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References: <20240409155250.3660517-1-kyle.meyer@hpe.com> <20240409155250.3660517-2-kyle.meyer@hpe.com>
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From: Vincent Guittot <vincent.guittot@linaro.org>
Date: Wed, 10 Apr 2024 09:26:08 +0200
Message-ID: <CAKfTPtC+d++V0T+C-O5fBy=i4BpEzvMib6eQYsPt-trhx2a1Jw@mail.gmail.com>
Subject: Re: [PATCH 1/2 RESEND] cpumask: Add for_each_cpu_from()
To: Kyle Meyer <kyle.meyer@hpe.com>
Cc: linux-kernel@vger.kernel.org, yury.norov@gmail.com, 
	andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, mingo@redhat.com, 
	peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, 
	rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, 
	vschneid@redhat.com, russ.anderson@hpe.com, dimitri.sivanich@hpe.com, 
	steve.wahl@hpe.com
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On Tue, 9 Apr 2024 at 17:54, Kyle Meyer <kyle.meyer@hpe.com> wrote:
>
> Add for_each_cpu_from() as a generic cpumask macro.
>
> for_each_cpu_from() is the same as for_each_cpu(), except it starts at
> @cpu instead of zero.
>
> Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
> Acked-by: Yury Norov <yury.norov@gmail.com>
> ---
>  include/linux/cpumask.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index 1c29947db848..655211db38ff 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -368,6 +368,16 @@ unsigned int __pure cpumask_next_wrap(int n, const struct cpumask *mask, int sta
>  #define for_each_cpu_or(cpu, mask1, mask2)                             \
>         for_each_or_bit(cpu, cpumask_bits(mask1), cpumask_bits(mask2), small_cpumask_bits)
>
> +/**
> + * for_each_cpu_from - iterate over every cpu present in @mask, starting at @cpu

So I was confused why you were not using for_each_cpu_wrap while
reading the description which has the same comment :
"
 * for_each_cpu_wrap - iterate over every cpu in a mask, starting at a
specified location
"
Could you clarify that it's not "every cpu present in @mask" but only
those after @cpu ?

> + * @cpu: the (optionally unsigned) integer iterator
> + * @mask: the cpumask pointer
> + *
> + * After the loop, cpu is >= nr_cpu_ids.
> + */
> +#define for_each_cpu_from(cpu, mask)                           \
> +       for_each_set_bit_from(cpu, cpumask_bits(mask), small_cpumask_bits)
> +
>  /**
>   * cpumask_any_but - return a "random" in a cpumask, but not this one.
>   * @mask: the cpumask to search
> --
> 2.44.0
>