linux-kernel - Re: [patch V3 12/17] timers: Silently ignore timers with a NULL function

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Message-ID: <87zgcgdau1.ffs@tglx>
Date:   Thu, 24 Nov 2022 09:18:46 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Anna-Maria Behnsen <anna-maria@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        Arnd Bergmann <arnd@...db.de>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-bluetooth@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        Jacob Keller <jacob.e.keller@...el.com>
Subject: Re: [patch V3 12/17] timers: Silently ignore timers with a NULL
 function

On Thu, Nov 24 2022 at 08:37, Anna-Maria Behnsen wrote:

> On Wed, 23 Nov 2022, Thomas Gleixner wrote:
>
>> Tearing down timers which have circular dependencies to other
>> functionality, e.g. workqueues, where the timer can schedule work and work
>> can arm timers, is not trivial.
>> 
>> In those cases it is desired to shutdown the timer in a way which prevents
>> rearming of the timer. The mechanism to do so is to set timer->function to
>> NULL and use this as an indicator for the timer arming functions to ignore
>> the (re)arm request.
>> 
>> In preparation for that replace the warnings in the relevant code paths
>> with checks for timer->function == NULL. If the pointer is NULLL, then
>
> s/NULLL/NULL

Bah. I should have went to the bar instead of trying to fix this.