Re: [PATCH v22 2/5] ring-buffer: Introducing ring-buffer mapping functions

Vincent Donnefort
2024-05-10T11:03:18Z

[...]

> > > +
> > > + while (s < nr_subbufs && p < nr_pages) {
> > > + struct page *page = virt_to_page(cpu_buffer->subbuf_ids[s]);
> > > + int off = 0;
> > > +
> > > + for (; off < (1 << (subbuf_order)); off++, page++) {
> > > + if (p >= nr_pages)
> > > + break;
> > > +
> > > + pages[p++] = page;
> > > + }
> > > + s++;
> > > + }
> >
> > The above can be made to:
> >
> > while (p < nr_pages) {
> > struct page *page;
> > int off = 0;
> >
> > if (WARN_ON_ONCE(s >= nr_subbufs))
> > break;
>
> I'm not particularly happy about us calling vm_insert_pages with NULL
> pointers stored in pages.
>
> Should we instead do
>
> if (WARN_ON_ONCE(s >= nr_subbufs)) {
> err = -EINVAL;
> goto out;
> }
>
> ?

I could also nr_pages = p in the event of s >= nr_subbufs... but that
really that shouldn't happen so let's return an error.

>
> --
> Cheers,
>
> David / dhildenb
>