[RFCv2 3/3] staging: ion: limit pool size

[Gioh Kim]

This patch limits pool size by page unit.

Signed-off-by: Gioh Kim <gioh.kim at lge.com>
---
 drivers/staging/android/ion/Kconfig         |    4 ++++
 drivers/staging/android/ion/ion_page_pool.c |   26 ++++++++++++++++----------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
index 3452346..e6b1a54 100644
--- a/drivers/staging/android/ion/Kconfig
+++ b/drivers/staging/android/ion/Kconfig
@@ -33,3 +33,7 @@ config ION_TEGRA
 	help
 	  Choose this option if you wish to use ion on an nVidia Tegra.
 
+config ION_POOL_LIMIT
+	int "Limit count of pages in pool"
+	depends on ION
+	default "0"
diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 165152f..d63e93f 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -22,8 +22,11 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
+#include <linux/kconfig.h>
 #include "ion_priv.h"
 
+#define POOL_LIMIT CONFIG_ION_POOL_LIMIT
+
 static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
 {
 	struct page *page = alloc_pages(pool->gfp_mask, pool->order);
@@ -41,8 +44,21 @@ static void ion_page_pool_free_pages(struct ion_page_pool *pool,
 	__free_pages(page, pool->order);
 }
 
+static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
+{
+	int count = pool->low_count;
+
+	if (high)
+		count += pool->high_count;
+
+	return count << pool->order;
+}
+
 static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
 {
+	if (POOL_LIMIT && ion_page_pool_total(pool, 1) > POOL_LIMIT)
+		return 1;
+
 	mutex_lock(&pool->mutex);
 	if (PageHighMem(page)) {
 		list_add_tail(&page->lru, &pool->high_items);
@@ -103,16 +119,6 @@ void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
 		ion_page_pool_free_pages(pool, page);
 }
 
-static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
-{
-	int count = pool->low_count;
-
-	if (high)
-		count += pool->high_count;
-
-	return count << pool->order;
-}
-
 int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 				int nr_to_scan)
 {
-- 
1.7.9.5