linux-kernel - Re: [PATCH] tick: Remove unreasonable detached state set in tick

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aLb2CIlAoaIsY4H8@localhost.localdomain>
Date: Tue, 2 Sep 2025 15:50:00 +0200
From: Frederic Weisbecker <frederic@...nel.org>
To: Bibo Mao <maobibo@...ngson.cn>
Cc: Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tick: Remove unreasonable detached state set in
 tick_shutdown()

Le Thu, Aug 07, 2025 at 11:59:54AM +0800, Bibo Mao a écrit :
> Function clockevents_switch_state() will check whether it has already
> switched to specified state, do nothing if it has.
> 
> In function tick_shutdown(), it will set detached state at first and
> call clockevents_switch_state() in clockevents_exchange_device(). The
> function clockevents_switch_state() will do nothing since it is already
> detached state. So the tick timer device will not be shutdown when CPU
> is offline. In guest VM system, timer interrupt will prevent vCPU to sleep
> if vCPU is hot removed.
> 
> Here remove state set before calling clockevents_exchange_device(),
> its state will be set in function clockevents_switch_state() if it
> succeeds to do so.
> 
> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>

Good catch. Looking back, it has been that way since the introduction
of clockevents and tick. Therefore it's not a regression and probably
not worth a Fixes: tag.

Reviewed-by: Frederic Weisbecker <frederic@...nel.org>

-- 
Frederic Weisbecker
SUSE Labs