Re: [PATCH v3 02/12] smp: Enable preemption early in smp_call_function_single

[Steven Rostedt]

On Wed, 18 Mar 2026 12:56:28 +0800
"Chuyi Zhou" <zhouchuyi@xxxxxxxxxxxxx> wrote:

> diff --git a/kernel/smp.c b/kernel/smp.c
> index fc1f7a964616..b603d4229f95 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -685,11 +685,16 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
>  
>  	err = generic_exec_single(cpu, csd);
>  
> +	/*
> +	 * @csd is stack-allocated when @wait is true. No concurrent access
> +	 * except from the IPI completion path, so we can re-enable preemption
> +	 * early to reduce latency.
> +	 */

Thanks for the comment. I walked through the code and this looks fine to me.

> +	put_cpu();
> +
>  	if (wait)
>  		csd_lock_wait(csd);
>  
> -	put_cpu();
> -
>  	return err;

Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>

-- Steve