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

From: Gioh Kim
Date: Thu Oct 23 2014 - 19:32:03 EST




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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