# Re: \[PATCH v2 04/11\] sched: Simplify wake\_up\_\*idle\*()

- From: Qian Cai \<hidden\>
- Date: 2021-10-19 19:22:51 
- List: live-patching
- Page: https://ratatoskr.run/live-patching/2021/10/1547515
- Thread: https://ratatoskr.run/live-patching/2021/09/1525995/t.md

```text


On 10/19/21 11:50 AM, Peter Zijlstra wrote:
>>> 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
> 
> Bah, for_each_possible_cpu(), lemme update the patch, I'm sure the
> robots will scream bloody murder on that too.

This survived the regression tests here.
```