[PATCHv3 1/2] powerpc/pseries: group lmb operation and memblock's

[Pingfan Liu]

On Thu, Jul 23, 2020 at 10:41 PM Nathan Lynch <nathanl at linux.ibm.com> wrote:
>
> Pingfan Liu <kernelfans at gmail.com> writes:
> > This patch prepares for the incoming patch which swaps the order of KOBJ_
> > uevent and dt's updating.
> >
> > It has no functional effect, just groups lmb operation and memblock's in
> > order to insert dt updating operation easily, and makes it easier to
> > review.
>
> ...
>
> > diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
> > index 5d545b7..1a3ac3b 100644
> > --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
> > +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
> > @@ -355,7 +355,8 @@ static int dlpar_add_lmb(struct drmem_lmb *);
> >  static int dlpar_remove_lmb(struct drmem_lmb *lmb)
> >  {
> >       unsigned long block_sz;
> > -     int rc;
> > +     phys_addr_t base_addr;
> > +     int rc, nid;
> >
> >       if (!lmb_is_removable(lmb))
> >               return -EINVAL;
> > @@ -364,17 +365,19 @@ static int dlpar_remove_lmb(struct drmem_lmb *lmb)
> >       if (rc)
> >               return rc;
> >
> > +     base_addr = lmb->base_addr;
> > +     nid = lmb->nid;
> >       block_sz = pseries_memory_block_size();
> >
> > -     __remove_memory(lmb->nid, lmb->base_addr, block_sz);
> > -
> > -     /* Update memory regions for memory remove */
> > -     memblock_remove(lmb->base_addr, block_sz);
> > -
> >       invalidate_lmb_associativity_index(lmb);
> >       lmb_clear_nid(lmb);
> >       lmb->flags &= ~DRCONF_MEM_ASSIGNED;
> >
> > +     __remove_memory(nid, base_addr, block_sz);
> > +
> > +     /* Update memory regions for memory remove */
> > +     memblock_remove(base_addr, block_sz);
> > +
> >       return 0;
> >  }
>
> I don't understand; the commit message should not claim this has no
> functional effect when it changes the order of operations like
> this. Maybe this is an improvement over the current behavior, but it's
> not explained why it would be.
One group of functions, which name contains lmb, are powerpc specific,
and used to form dt.

The other group __remove_memory() and memblock_remove() are integrated
with linux mm.

And [2/2] arrange dt-updating just before __remove_memory()

Thanks,
Pingfan