Re: [PATCH v2 2/2] of, numa: Fetch empty NUMA node ID from distance map

[Gavin Shan]

Hi Rob,

On 9/28/21 12:49 AM, Rob Herring wrote:
> On Mon, Sep 27, 2021 at 1:42 AM Gavin Shan <gshan@xxxxxxxxxx> wrote:
> > There is no device node for the empty NUMA node. However, the
> > corresponding NUMA node ID and distance map is still valid in
> > "numa-distance-map-v1" compatible device node.
> >
> > This fetches the NUMA node ID and distance map for these empty
> > NUMA node from "numa-distance-map-v1" compatible device node.
>
> This is much nicer.

Indeed, thanks for your suggestions :)

> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   drivers/of/of_numa.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/of/of_numa.c b/drivers/of/of_numa.c
> > index fe6b13608e51..5949829a1b00 100644
> > --- a/drivers/of/of_numa.c
> > +++ b/drivers/of/of_numa.c
> > @@ -111,6 +111,8 @@ static int __init of_numa_parse_distance_map_v1(struct device_node *map)
> >                          return -EINVAL;
> >                  }
> >
> > +               node_set(nodea, numa_nodes_parsed);
> > +
>
> With this, couldn't we remove of_numa_parse_cpu_nodes() as the only
> thing it does is node_set()?

I don't think so for couple of reasons:

(1) With problematic device-tree, the distance map node might be missed
    or incomplete. In this case, of_numa_parse_cpu_nodes() still helps.

(2) @numa_nodes_parsed is also updated when the memory nodes are iterated
    in of_numa_parse_memory_nodes() and numa_add_memblk().

So @numa_nodes_parsed, which is synchronized to @node_possible_map afterwards,
is the gathering output of CPU nodes, memory nodes and distance map node.

> >                  numa_set_distance(nodea, nodeb, distance);
> >
> >                  /* Set default distance of node B->A same as A->B */

Thanks,
Gavin