linux-kernel - Re: [PATCH RFC] tick/nohz: fix data races in get_cpu_idle_time

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Message-ID: <Y9lyx38kHmKEF5CQ@hirez.programming.kicks-ass.net>
Date:   Tue, 31 Jan 2023 20:57:59 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Yu Liao <liaoyu15@...wei.com>, fweisbec@...il.com,
        mingo@...nel.org, liwei391@...wei.com, adobriyan@...il.com,
        mirsad.todorovac@....unizg.hr, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] tick/nohz: fix data races in get_cpu_idle_time_us()

On Tue, Jan 31, 2023 at 03:44:00PM +0100, Thomas Gleixner wrote:

> P.S.: I hate the spinlock in the idle code path, but I don't have a
>       better idea.

seqcount? It would avoid the obvious interleave and put most of the onus
on the reader (which never happens anyway).