Re: [PATCH v2] MIPS: smp: report dying CPU to RCU in stop_this_cpu()

[Jonas Jelonek]

On 15.06.26 09:30, Huacai Chen wrote:
>> [...]
>>
>>> However, synchronize_rcu() only gets called in the
>>> IS_ENABLED(CONFIG_PREEMPT_RT) case, so I think your configuration
>>> needs PREEMPT_RT, right?
>>>
>>> You said this is the default behavior, but PREEMPT_RT is not enabled by default.
>> The condition where this is added has two parts, see [1]. While PREEMPT_RT
>> isn't active for MIPS, arch_irq_work_has_interrupt gives false for MIPS (since
>> there is no implementation and it falls back to the generic one). This then
>> also calls synchronize_rcu.
> Sorry, this is my mistake, then what's your preemption model? There
> are too many config files for MIPS now.

I'm using PREEMPT_NONE, apparently default for all targets in OpenWrt.

> Huacai
>
>>> Huacai
>>>
>> Best,
>> Jonas
>>
>> [1] https://elixir.bootlin.com/linux/v7.1-rc7/source/kernel/irq_work.c#L291-L302

Best,
Jonas