Re: [PATCH next v1 1/2] dump_stack: move cpu lock to printk.c

[John Ogness]

On 2021-06-01, John Ogness <john.ogness@xxxxxxxxxxxxx> wrote:
>> Is there any particular reason this does
>>
>> 	preempt_disable();
>> 	cpu = smp_processor_id();
>> 	local_irq_safe();
>>
>> instead of
>>
>> 	local_irq_safe();
>> 	cpu = raw_smp_processor_id();
>>
>> ?
>
> If the lock is owned by another CPU, there is no need to disable
> interrupts for this CPU. (The local_irq_save() is conditional.)

The cpu lock implementation from dump_stack() also keeps preemption
continually enabled while spinning. I used the cpu lock implementation
from PREEMPT_RT. But for my v2 I will adopt the same ordering from
dump_stack(), as you are suggesting.

Thanks for pointing that out.

John Ogness