Re: [PATCH] tick: Remove unreasonable detached state set in tick_shutdown()

[Frederic Weisbecker <frederic@kernel.org>]

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@loongson.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@kernel.org>

-- 
Frederic Weisbecker
SUSE Labs