Dave Jiang wrote:
>
>
> On 3/6/24 7:53 AM, Jonathan Cameron wrote:
> > On Tue, 20 Feb 2024 16:12:40 -0700
> > Dave Jiang <dave.jiang@xxxxxxxxx> wrote:
> >
> >> When the CXL region is formed, the driver would computed the performance
> >> data for the region. However this data is not available at the node data
> >> collection that has been populated by the HMAT during kernel
> >> initialization. Add a memory hotplug notifier to update the access
> >> coordinates to the 'struct memory_target' context kept by the
> >> HMAT_REPORTING code.
> >>
> >> Add CXL_CALLBACK_PRI for a memory hotplug callback priority. Set the
> >> priority number to be called before HMAT_CALLBACK_PRI. The CXL update must
> >> happen before hmat_callback().
> >>
> >> A new HMAT_REPORING helper hmat_update_target_coordinates() is added in
> >
> > REPORTING
> >
> >> order to allow CXL to update the memory_target access coordinates.
> >>
> >> A new ext_updated member is added to the memory_target to indicate that
> >> the access coordinates within the memory_target has been updated by an
> >> external agent such as CXL. This prevents data being overwritten by the
> >> hmat_update_target_attrs() triggered by hmat_callback().
> >>
> >> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> >> Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> >> Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> >> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
[..]
> >> +
> >> static int cxl_region_probe(struct device *dev)
> >> {
> >> struct cxl_region *cxlr = to_cxl_region(dev);
> >> @@ -3081,6 +3151,12 @@ static int cxl_region_probe(struct device *dev)
> >> goto out;
> >> }
> >>
> >> + cxlr->memory_notifier.notifier_call = cxl_region_perf_attrs_callback;
> >> + cxlr->memory_notifier.priority = CXL_CALLBACK_PRI;
> >> + register_memory_notifier(&cxlr->memory_notifier);
> >> + rc = devm_add_action_or_reset(&cxlr->dev, remove_coord_notifier,
> >> + &cxlr->memory_notifier);
> >> +
> >
> > Check rc? Very unlikely to fail, but you never know..
>
> It's actually checked a few lines down after cxl_region_sem gets released. Probably too far away for diff to include it.
Why does this need to be done late in cxl_region_probe() and not
something like devm_cxl_add_region() and unregistered in
unregister_region()?
