Re: [PATCH 04/11] cxl/core: Clamp max lock_class

[Dan Williams]

On Wed, Mar 9, 2022 at 10:27 AM Jonathan Cameron
<Jonathan.Cameron@xxxxxxxxxx> wrote:
>
> On Mon, 28 Feb 2022 18:49:11 -0800
> Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
> > MAX_LOCKDEP_SUBCLASSES limits the depth of the CXL topology that can be
> > validated by lockdep. Given that the cxl_test topology is already at
> > this limit collapse some of the levels and clamp the max depth.
> >
> > Cc: Alison Schofield <alison.schofield@xxxxxxxxx>
> > Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> > Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
> > Cc: Ben Widawsky <ben.widawsky@xxxxxxxxx>
> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> > ---
> >  drivers/cxl/cxl.h |   21 +++++++++++++++++----
> >  1 file changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> > index 97e6ca7e4940..1357a245037d 100644
> > --- a/drivers/cxl/cxl.h
> > +++ b/drivers/cxl/cxl.h
> > @@ -501,20 +501,33 @@ enum cxl_lock_class {
> >       CXL_ANON_LOCK,
> >       CXL_NVDIMM_LOCK,
> >       CXL_NVDIMM_BRIDGE_LOCK,
>
> I'd be tempted to give explicit value to the one above as well
> so it's immediate clear there is deliberate duplication here.

Sounds good.

I also notice that clamp_lock_class() should return -1 when it wants
to disable validation, not zero.