linux-kernel - Re: [PATCH v3 1/2] smp: Introduce a helper function to check for pending IPIs

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Message-ID: <875xbty157.ffs@tglx>
Date: Sat, 01 Nov 2025 20:59:48 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Ulf Hansson <ulf.hansson@...aro.org>, "Rafael J . Wysocki"
 <rafael@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>, Marc Zyngier <maz@...nel.org>,
 Maulik Shah <quic_mkshah@...cinc.com>, Sudeep Holla
 <sudeep.holla@....com>, Daniel Lezcano <daniel.lezcano@...aro.org>,
 Vincent Guittot <vincent.guittot@...aro.org>, Ben Horgan
 <ben.horgan@....com>, linux-pm@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, Ulf
 Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH v3 1/2] smp: Introduce a helper function to check for
 pending IPIs

On Fri, Oct 31 2025 at 12:00, Ulf Hansson wrote:
> +/**
> + * cpus_peek_for_pending_ipi - Check for pending IPI for CPUs
> + * @mask: The CPU mask for the CPUs to check.
> + *
> + * This function walks through the @mask to check if there are any pending IPIs
> + * scheduled, for any of the CPUs in the @mask.
> + *
> + * It's important for the caller to know that this function does not guarantee
> + * correctness. It provides a snapshot, while being as lightweight as possible.

This read clumsy. Just say:

  * It does not guarantee correctness as it only can provide a racy snapshot.

or something like that.

> + * Returns true if there is a pending IPI scheduled and false otherwise.
> + */
> +bool cpus_peek_for_pending_ipi(const struct cpumask *mask)
> +{
> +	unsigned int cpu;
> +
> +	for_each_cpu(cpu, mask) {
> +		if (!llist_empty(per_cpu_ptr(&call_single_queue, cpu)))
> +			return true;
> +	}
> +
> +        return false;
   ^^^^^^^^
White space damage. Spaces instead of TAB.

Thanks,

        tglx