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

[Devendra Naga]

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.

> +               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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