linux-kernel - Re: [RFC PATCH 1/2] cpumask: Implement cpumask_next

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Message-ID: <Ztdjd9s-eLKrTU9g@yury-ThinkPad>
Date: Tue, 3 Sep 2024 12:28:55 -0700
From: Yury Norov <yury.norov@...il.com>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	linux-kernel@...r.kernel.org,
	Valentin Schneider <vschneid@...hat.com>,
	Mel Gorman <mgorman@...e.de>, Steven Rostedt <rostedt@...dmis.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Ben Segall <bsegall@...gle.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: Re: [RFC PATCH 1/2] cpumask: Implement cpumask_next_andnot

On Tue, Sep 03, 2024 at 03:06:49PM -0400, Mathieu Desnoyers wrote:
> Allow finding the next bit within two input cpumasks which is
> respectively one and zero.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Cc: Yury Norov <yury.norov@...il.com>
> Cc: Rasmus Villemoes <linux@...musvillemoes.dk>

Acked-by: Yury Norov <yury.norov@...il.com>

> ---
>  include/linux/cpumask.h | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index 23686bed441d..5da1c66cfa65 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -246,6 +246,23 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
>  	return find_next_zero_bit(cpumask_bits(srcp), small_cpumask_bits, n+1);
>  }
>  
> +/**
> + * cpumask_next_andnot - return the next cpu from *srcp1 & ~*srcp2
> + * @n: the cpu prior to the place to search (ie. return will be > @n)
> + * @src1p: the first input
> + * @src2p: the second input
> + *
> + * Returns >= nr_cpu_ids if no cpus match in both.
> + */
> +static __always_inline
> +unsigned int cpumask_next_andnot(int n, const struct cpumask *srcp1, const struct cpumask *srcp2)
> +{
> +	/* -1 is a legal arg here. */
> +	if (n != -1)
> +		cpumask_check(n);
> +	return find_next_andnot_bit(cpumask_bits(srcp1), cpumask_bits(srcp2), small_cpumask_bits, n+1);
> +}
> +
>  #if NR_CPUS == 1
>  /* Uniprocessor: there is only one valid CPU */
>  static inline unsigned int cpumask_local_spread(unsigned int i, int node)
> -- 
> 2.39.2