Re: [PATCH 07/17] sched_ext: Add topological CPU IDs (cids)

[Tejun Heo]

Hello, Kuba.

On Tue, Apr 28, 2026 at 01:00:22PM +0000, Kuba Piecuch wrote:
> Hi Tejun,
> 
> Relaying a minor finding from Sashiko's review:
> https://sashiko.dev/#/patchset/20260424172721.3458520-1-tj%40kernel.org
> 
> Might also be worth having a look at the findings for other patches in the
> series.

I submitted a PR to make it send review emails but that didn't seem to have
worked. If you look into how to make it send review emails, I'd appreciate
it.

> > @@ -6727,6 +6728,16 @@ static void scx_root_enable_workfn(struct kthread_work *work)
> >  	 */
> >  	cpus_read_lock();
> >  
> > +	/*
> > +	 * Build the cid mapping before publishing scx_root. The cid kfuncs
> > +	 * dereference the cid arrays unconditionally once scx_prog_sched()
> > +	 * returns non-NULL; the rcu_assign_pointer() below pairs with their
> > +	 * rcu_dereference() to make the populated arrays visible.
> > +	 */
> > +	ret = scx_cid_init(sch);
> > +	if (ret)
> > +		goto err_disable;
> > +
> 
> Are we missing cpus_read_unlock() on the error path here?

Yeah, fixed this and several other valid ones that sashiko found. Will post
the next round soon.

Thanks.

-- 
tejun