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Message-ID: <20170527074746.6w7vakbuelurs245@linutronix.de>
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
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