Re: [PATCH v9 02/13] lib/group_cpus: remove dead !SMP code

Aaron Tomlin
2026-04-01T19:31:50Z

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On Wed, Apr 01, 2026 at 02:29:08PM +0200, Sebastian Andrzej Siewior wrote:
> On 2026-03-30 18:10:36 [-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").
>
> !SMP is not dead code here. You can very much compile a !SMP kernel at
> which point the code below will be used. It is more that the sched
> department decided that scheduler's maintenance will be easier since we
> don't have to deal with !SMP case anymore.
>
> If you wish to remove the !SMP case here you need to argue as such.
>
> > Signed-off-by: Daniel Wagner <wagi@kernel.org>
> > Reviewed-by: Hannes Reinecke <hare@suse.de>
>
> The previous patch, this one and probably the following lack a
> Signed-off-by line with your name.
>
Hi Sebastian,

Thank you for your review and for clarifying the precise nature of the !SMP
configuration.

Fair point. Describing it broadly as "dead code" is indeed inaccurate,
given that one can certainly still compile a uniprocessor kernel. I shall
amend the commit message in the next series to properly articulate the
reasoning: we are removing this specific !SMP fallback logic because the
core scheduler now mandates SMP unconditionally (as per commit
cac5cefbade9), rendering this particular handling redundant for our
purposes, rather than it being globally obsolete.

Furthermore, my apologies for the oversight regarding the missing
Signed-off-by tags.

Kind regards,
--
Aaron Tomlin

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