linux-kernel - Re: [patch V2 9/9] tasklets: Prevent kill/unlock

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Message-ID: <87tusx63q8.fsf@nanos.tec.linutronix.de>
Date:   Mon, 07 Dec 2020 16:22:07 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paul McKenney <paulmck@...nel.org>
Subject: Re: [patch V2 9/9] tasklets: Prevent kill/unlock_wait deadlock on RT

On Mon, Dec 07 2020 at 15:00, Sebastian Andrzej Siewior wrote:
> On 2020-12-07 12:47:43 [+0100], Peter Zijlstra wrote:
>> On Fri, Dec 04, 2020 at 06:02:00PM +0100, Thomas Gleixner wrote:
>> > @@ -825,7 +848,20 @@ void tasklet_kill(struct tasklet_struct
>> >  
>> >  	while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
>> >  		do {
>> > -			yield();
>> >  		} while (test_bit(TASKLET_STATE_SCHED, &t->state));
>> >  	}
>> >  	tasklet_unlock_wait(t);
>> 
>> 
>> Egads... should we not start by doing something like this?
>
> So we keep the RT part as-is and replace the non-RT bits with this?

No. It would work for both.