Re: [PATCH v12 02/13] lib/group_cpus: remove dead !SMP code

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2026-04-22 14:52:04 [-0400], Aaron Tomlin wrote:
> From: Daniel Wagner <wagi@kernel.org>
> 
> The support for the !SMP configuration has been removed from the core by
> commit cac5cefbade9 ("sched/smp: Make SMP unconditional").
> 
> While one can technically still compile a uniprocessor kernel, the core
> scheduler now mandates SMP unconditionally, rendering this particular
> !SMP fallback handling redundant. Therefore, remove the #ifdef CONFIG_SMP
> guards and the fallback logic.
> 
> Signed-off-by: Daniel Wagner <wagi@kernel.org>
> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> [atomlin: Updated commit message to clarify !SMP removal context]

This look unchanged vs previous submission. You could explain why you
want to remove the !SMP case. It looks like the !SMP makes things
easier ;) I don't know how much of this gets removed because of !SMP
code elsewhere.

The description still does not make sense/ is accurate.

> Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
> ---
>  lib/group_cpus.c | 20 --------------------
>  1 file changed, 20 deletions(-)
> 
> diff --git a/lib/group_cpus.c b/lib/group_cpus.c
> index e6e18d7a49bb..b8d54398f88a 100644
> --- a/lib/group_cpus.c
> +++ b/lib/group_cpus.c
> @@ -9,8 +9,6 @@
>  #include <linux/sort.h>
>  #include <linux/group_cpus.h>
>  
> -#ifdef CONFIG_SMP
> -
>  static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
>  				unsigned int cpus_per_grp)
>  {
> @@ -564,22 +562,4 @@ struct cpumask *group_cpus_evenly(unsigned int numgrps, unsigned int *nummasks)
>  	*nummasks = min(nr_present + nr_others, numgrps);
>  	return masks;
>  }
> -#else /* CONFIG_SMP */
> -struct cpumask *group_cpus_evenly(unsigned int numgrps, unsigned int *nummasks)
> -{
> -	struct cpumask *masks;
> -
> -	if (numgrps == 0)
> -		return NULL;
> -
> -	masks = kzalloc_objs(*masks, numgrps);
> -	if (!masks)
> -		return NULL;
> -
> -	/* assign all CPUs(cpu 0) to the 1st group only */
> -	cpumask_copy(&masks[0], cpu_possible_mask);
> -	*nummasks = 1;
> -	return masks;
> -}
> -#endif /* CONFIG_SMP */
>  EXPORT_SYMBOL_GPL(group_cpus_evenly);

Sebastian