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From:   Thomas Gleixner <tglx@linutronix.de>
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To:     Li RongQing <lirongqing@baidu.com>, linux-kernel@vger.kernel.org,
        john.stultz@linaro.org
Subject: Re: [PATCH] alarmtimer: Do not mess with an enqueued hrtimer
In-Reply-To: <1609997600-13503-1-git-send-email-lirongqing@baidu.com>
References: <1609997600-13503-1-git-send-email-lirongqing@baidu.com>
Date:   Fri, 05 Feb 2021 18:07:35 +0100
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On Thu, Jan 07 2021 at 13:33, Li RongQing wrote:
> when an hrtimer is enqueued already, its expires should be not
> changed, otherwise, this will corrupts the ordering of the
> timerqueue RB tree, if other hrtimer is enqueued before this
> hrtimer is restarted, whole RB tree is completely hosed
>
> Fixes: 6cffe00f7d4e ("alarmtimer: Add functions for timerfd support")

I can't see what this fixes. alarm_restart() is only invoked when the
alarm has expired which means that the timer _cannot_ be queued.

Thanks,

        tglx