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Date: Thu, 4 Sep 2025 12:33:01 +0200
From: Frederic Weisbecker <frederic@kernel.org>
To: Bibo Mao <maobibo@loongson.cn>
Cc: Huacai Chen <chenhuacai@kernel.org>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
	loongarch@lists.linux.dev, Xianglai Li <lixianglai@loongson.cn>
Subject: Re: [PATCH v2 1/2] tick: Remove unreasonable detached state set in
 tick_shutdown()
Message-ID: <aLlq3Um6y5Ez07ak@localhost.localdomain>
References: <20250904071732.3513694-1-maobibo@loongson.cn>
 <20250904071732.3513694-2-maobibo@loongson.cn>
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In-Reply-To: <20250904071732.3513694-2-maobibo@loongson.cn>

Le Thu, Sep 04, 2025 at 03:17:31PM +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.
> 
> Fixes: bf9a001fb8e4 ("clocksource/drivers/timer-tegra: Remove clockevents shutdown call on offlining")
> Fixes: cd165ce8314f ("clocksource/drivers/qcom: Remove clockevents shutdown call on offlining")
> Fixes: 30f8c70a85bc ("clocksource/drivers/armada-370-xp: Remove clockevents shutdown call on offlining")
> Fixes: ba23b6c7f974 ("clocksource/drivers/exynos_mct: Remove clockevents shutdown call on offlining")
> Fixes: 15b810e0496e ("clocksource/drivers/arm_global_timer: Remove clockevents shutdown call on offlining")
> Fixes: 78b5c2ca5f27 ("clocksource/drivers/arm_arch_timer: Remove clockevents shutdown call on offlining")
> Fixes: 900053d9eedf ("ARM: smp_twd: Remove clockevents shutdown call on offlining")
> 
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

Thanks a lot!

-- 
Frederic Weisbecker
SUSE Labs