linux-kernel - Re: [PATCH v2 04/11] sched: Simplify wake_up

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Date:   Tue, 19 Oct 2021 11:32:15 -0400
From:   Qian Cai <quic_qiancai@...cinc.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     <gor@...ux.ibm.com>, <jpoimboe@...hat.com>, <jikos@...nel.org>,
        <mbenes@...e.cz>, <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 04/11] sched: Simplify wake_up_*idle*()



On 10/19/2021 5:10 AM, Peter Zijlstra wrote:
> Here, hows this then?
> 
> ---
> diff --git a/kernel/smp.c b/kernel/smp.c
> index ad0b68a3a3d3..61ddc7a3bafa 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -1170,14 +1170,12 @@ void wake_up_all_idle_cpus(void)
>  {
>  	int cpu;
>  
> -	cpus_read_lock();
> -	for_each_online_cpu(cpu) {
> -		if (cpu == raw_smp_processor_id())
> -			continue;
> -
> -		wake_up_if_idle(cpu);
> +	for_each_cpu(cpu) {
> +		preempt_disable();
> +		if (cpu != smp_processor_id() && cpu_online(cpu))
> +			wake_up_if_idle(cpu);
> +		preempt_enable();
>  	}
> -	cpus_read_unlock();
>  }
>  EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus);

This does not compile.

kernel/smp.c:1173:18: error: macro "for_each_cpu" requires 2 arguments, but only 1 given