linux-kernel - Re: [PATCH] Revert "timers: Don't wake ktimersoftd on every tick"

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Date:   Sat, 27 May 2017 09:47:47 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Anna-Maria Gleixner <anna-maria@...utronix.de>
Cc:     Haris Okanovic <haris.okanovic@...com>,
        linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, julia.cartwright@...com, gratian.crisan@...com
Subject: Re: [PATCH] Revert "timers: Don't wake ktimersoftd on every tick"

On 2017-05-26 19:16:07 [+0200], Anna-Maria Gleixner wrote:
> This reverts commit 032f93cae150a.
> 
> The problem is that the look ahead optimization from the tick timer
> interrupt context can race with the softirq thread expiring timer. As
> a consequence the temporary hlist heads which hold the to expire
> timers are overwritten and the timers which are already removed from
> the wheel bucket for expiry are now dangling w/o a list head.
> 
> That means those timers never get expired. If one of those timers is
> canceled the removal operation will result in a hlist corruption.
> 
> Signed-off-by: Anna-Maria Gleixner <anna-maria@...utronix.de>

Applied

Sebastian