Re: [PATCH v1] ring-buffer: Clean up resize_disabled checks

[Vincent Donnefort <vdonnefort@google.com>]

On Mon, Sep 14, 2026 at 08:09:24PM +0100, David CARLIER wrote:
> Hi Vincent.
> 
> > +   if (rb_resize_disabled(buffer, cpu_id)) {
> > +           err = -EBUSY;
> > +           goto out_err_unlock;
> > +   }
> 
> For a single CPU, this now happens before the nr_pages == cpu_buffer->nr_pages
> early exit, so writing the same size to per_cpu/cpuN/buffer_size_kb on a
> mapped or persistent instance CPU fails with EBUSY instead of succeeding.
> Intended ?

Actually no, I didn't see that it is also "fixing" this discrepancy between the
per_cpu buffer_size_kb and the global one.

It seems to me better to align the behaviour for both interface, but then it is
touching something that is user interface... 

Steven, WDYS?

> 
> > Additionally, remove the unnecessary cpumask_test_cpu in
> > ring_buffer_subbuf_order_set().
> 
> The install loop still has one.
> 
> Otherwise removing the second check is fine, the hotplug window is
> covered by the cpus_read_lock() patch I sent separately.
> 
> Cheers.

-- 
Vincent