linux-kernel - Re: [PATCH v2 05/11] sched,livepatch: Use wake_up_if

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Date:   Wed, 6 Oct 2021 11:16:21 +0200 (CEST)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Peter Zijlstra <peterz@...radead.org>
cc:     gor@...ux.ibm.com, jpoimboe@...hat.com, jikos@...nel.org,
        pmladek@...e.com, mingo@...nel.org, linux-kernel@...r.kernel.org,
        joe.lawrence@...hat.com, fweisbec@...il.com, tglx@...utronix.de,
        hca@...ux.ibm.com, svens@...ux.ibm.com, sumanthk@...ux.ibm.com,
        live-patching@...r.kernel.org, paulmck@...nel.org,
        rostedt@...dmis.org, x86@...nel.org
Subject: Re: [PATCH v2 05/11] sched,livepatch: Use wake_up_if_idle()

On Wed, 29 Sep 2021, Peter Zijlstra wrote:

> Make sure to prod idle CPUs so they call klp_update_patch_state().
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  kernel/livepatch/transition.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> --- a/kernel/livepatch/transition.c
> +++ b/kernel/livepatch/transition.c
> @@ -413,8 +413,11 @@ void klp_try_complete_transition(void)
>  	for_each_possible_cpu(cpu) {
>  		task = idle_task(cpu);
>  		if (cpu_online(cpu)) {
> -			if (!klp_try_switch_task(task))
> +			if (!klp_try_switch_task(task)) {
>  				complete = false;
> +				/* Make idle task go through the main loop. */
> +				wake_up_if_idle(cpu);
> +			}

Right, it should be enough.

Acked-by: Miroslav Benes <mbenes@...e.cz>

It would be nice to get Vasily's Tested-by tag on this one.

M