Re: [PATCH 2/2] nvdimm: Set device node in nd_device_register

[Alexander Duyck]

On 9/25/2018 2:32 PM, Dan Williams wrote:
> On Tue, Sep 25, 2018 at 2:11 PM Alexander Duyck
> <alexander.h.duyck@xxxxxxxxxxxxxxx> wrote:
> > On 9/25/2018 2:08 PM, Dan Williams wrote:
> > > On Tue, Sep 25, 2018 at 1:56 PM Alexander Duyck
> > > <alexander.h.duyck@xxxxxxxxxxxxxxx> wrote:
> > > > This change makes it so that we don't repeatedly overwrite the device node
> > > > for nvdimm regions. The earliest we can set the node is immediately after
> > > > calling device init, so I have moved the code there so we can avoid
> > > > rewriting the node with each uevent.
> > > >
> > > > Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
> > > > ---
> > > >    drivers/nvdimm/bus.c |   16 ++++++++++------
> > > >    1 file changed, 10 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
> > > > index 9148015ed803..96f4d0e1706a 100644
> > > > --- a/drivers/nvdimm/bus.c
> > > > +++ b/drivers/nvdimm/bus.c
> > > > @@ -54,12 +54,6 @@ static int to_nd_device_type(struct device *dev)
> > > >
> > > >    static int nvdimm_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
> > > >    {
> > > > -       /*
> > > > -        * Ensure that region devices always have their numa node set as
> > > > -        * early as possible.
> > > > -        */
> > > > -       if (is_nd_region(dev))
> > > > -               set_dev_node(dev, to_nd_region(dev)->numa_node);
> > > >           return add_uevent_var(env, "MODALIAS=" ND_DEVICE_MODALIAS_FMT,
> > > >                           to_nd_device_type(dev));
> > > >    }
> > > > @@ -519,6 +513,16 @@ void __nd_device_register(struct device *dev)
> > > >    void nd_device_register(struct device *dev)
> > > >    {
> > > >           device_initialize(dev);
> > > > +
> > > > +       /*
> > > > +        * Ensure that region devices always have their NUMA node set as
> > > > +        * early as possible. This way we are able to make certain that any
> > > > +        * memory associated with the creation and the creation itself of
> > > > +        * the region is associated with the correct node.
> > > > +        */
> > > > +       if (is_nd_region(dev))
> > > > +               set_dev_node(dev, to_nd_region(dev)->numa_node);
> > > > +
> > > >           __nd_device_register(dev);
> > >
> > > Any reason to not put this inside __nd_device_register()? If you're ok
> > > with that I can just fix up when applying.
> >
> > I put it here since regions never call __nd_device_register directly,
> > they always call nd_device_register. I figured that by placing it here
> > we reduce the impact of this on the other devices that aren't going to
> > need it.
>
> I can't imagine there's much of an impact because we're already
> reading the cacheline that has dev->parent so dev->type is already
> there. If we're going to add support for looking up the parent node to
> schedule namespace registration work to the proper core I would expect
> that to appear in the __nd_device_register() common code as well.
>
> In general the only consideration for calling nd_device_register() vs
> __nd_device_register() is whether or not you want a
> device_initialize() to occur.

Yeah, I kind of gathered that. If you want to move it feel free to.

- Alex