Re: [RFC 1/2] staging: ion: shrink page-pool by page unit

[Gioh Kim]

2014-10-24 ìì 8:16, Gioh Kim ì ê:
> 2014-10-24 ìì 5:36, Devendra Naga ì ê:
> > Hello,
> >
> > On Thu, Oct 23, 2014 at 6:22 PM, Gioh Kim <gioh.kim@xxxxxxx> wrote:
> > > This patch shrink page-pool by page unit.
> > >
> > > Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx>
> > > ---
> > >   drivers/staging/android/ion/ion_page_pool.c   |    5 +++--
> > >   drivers/staging/android/ion/ion_system_heap.c |    7 +++++--
> > >   2 files changed, 8 insertions(+), 4 deletions(-)
> >
> > >
> >
> > --- cut --
> >
> > > diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
> > > index da2a63c..36e73c3 100644
> > > --- a/drivers/staging/android/ion/ion_system_heap.c
> > > +++ b/drivers/staging/android/ion/ion_system_heap.c
> > > @@ -211,7 +211,7 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
> > >                                          int nr_to_scan)
> > >   {
> > >          struct ion_system_heap *sys_heap;
> > > -       int nr_total = 0;
> > > +       int nr_total = 0, nr_freed;
> > >          int i;
> > >
> > >          sys_heap = container_of(heap, struct ion_system_heap, heap);
> > > @@ -219,7 +219,10 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
> > >          for (i = 0; i < num_orders; i++) {
> > >                  struct ion_page_pool *pool = sys_heap->pools[i];
> > >
> > > -               nr_total += ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);
> > > +               nr_freed += ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);
> >
> > nr_freed is not initialised to zero. This might result in updating of
> > a garbage value stored initially after nr_freed is created.
>
> Yes, your're right. It's my mistake.
> I testes this on my platform with custom kernel and copied codes.
> I missed a line for it.
> I'm sorry.

Following is the correct code:
nr_freed = ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);

> > > +               nr_total += nr_freed;
> > > +               /* nr_to_scan can be negative */
> > > +               nr_to_scan -= nr_freed;
> > >          }
> > >
> > >          return nr_total;
> > > --
> > > 1.7.9.5
> > >
> > > --
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