linux-kernel - Re: [PATCH v2 5/6] entry,hrtimer: Push reprogramming timers into the interrupt return path

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Message-ID: <20260123150843.3f68d4cc@gandalf.local.home>
Date: Fri, 23 Jan 2026 15:08:43 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: tglx@...utronix.de, arnd@...db.de, anna-maria@...utronix.de,
 frederic@...nel.org, luto@...nel.org, mingo@...hat.com,
 juri.lelli@...hat.com, vincent.guittot@...aro.org,
 dietmar.eggemann@....com, bsegall@...gle.com, mgorman@...e.de,
 vschneid@...hat.com, linux-kernel@...r.kernel.org, oliver.sang@...el.com
Subject: Re: [PATCH v2 5/6] entry,hrtimer: Push reprogramming timers into
 the interrupt return path

On Wed, 21 Jan 2026 17:20:15 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> +#ifdef TIF_HRTIMER_REARM
> +void _hrtimer_rearm(void)
> +{
> +	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
> +	ktime_t now, expires_next;
> +
> +	lockdep_assert_irqs_disabled();
> +
> +	scoped_guard (raw_spinlock, &cpu_base->lock) {
> +		now = hrtimer_update_base(cpu_base);
> +		expires_next = hrtimer_update_next_event(cpu_base);
> +		__hrtimer_rearm(cpu_base, now, expires_next);
> +		clear_thread_flag(TIF_HRTIMER_REARM);
> +	}
> +}

I'm curious to why you decided to use scoped_guard() here and not just
guard() and not add the extra indentation? The function is small enough
where everything is expected to be protected by the spinlock.

-- Steve