Re: [PATCH v2 net-next] selftests: devmem: configure HDS threshold

[Stanislav Fomichev <stfomichev@gmail.com>]

On 07/03, Taehee Yoo wrote:
> On Thu, Jul 3, 2025 at 12:37 AM Stanislav Fomichev <stfomichev@gmail.com> wrote:
> >
> 
> Hi Stanislav,
> Thanks a lot for your review!
> 
> > On 07/02, Taehee Yoo wrote:
> > > The devmem TCP requires the hds-thresh value to be 0, but it doesn't
> > > change it automatically.
> > > Therefore, make configure_headersplit() sets hds-thresh value to 0.
> > >
> > > Signed-off-by: Taehee Yoo <ap420073@gmail.com>
> > > ---
> > >
> > > v2:
> > >  - Do not implement configure_hds_thresh().
> > >  - Make configure_headersplit() sets hds-thresh to 0.
> > >
> > >  tools/testing/selftests/drivers/net/hw/ncdevmem.c | 11 ++++++++++-
> > >  1 file changed, 10 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> > > index cc9b40d9c5d5..52b72de11e3b 100644
> > > --- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> > > +++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
> > > @@ -331,6 +331,12 @@ static int configure_headersplit(bool on)
> > >       ret = ethtool_rings_set(ys, req);
> > >       if (ret < 0)
> > >               fprintf(stderr, "YNL failed: %s\n", ys->err.msg);
> > > +     if (on) {
> > > +             ethtool_rings_set_req_set_hds_thresh(req, 0);
> > > +             ret = ethtool_rings_set(ys, req);
> >
> > Why call ethtool_rings_set again here? Can we move ethtool_rings_set_req_set_hds_thresh
> > to be after ethtool_rings_set_req_set_tcp_data_split ?
> 
> I think tcp-data-split will fail if a driver doesn't support
> hds-thresh, even if it supports tcp-data-split.
> So, I separated them.

Sorry for going back and forth on this, but in this case your v1 is
better (maybe improve it by not printing an error for 'not supported'
errno). And will probably better be suited for Jakub's suggestion of
adding undo.