[PATCH v3 1/2] staging: android: Remove BUG_ON from ion_page_pool.c

[Tomer Samara]

BUG_ON() is removed at ion_page_pool.c and add error handleing to
ion_page_pool_shrink

Fixes the following issue:
Avoid crashing the kernel - try using WARN_ON & recovery code ratherthan BUG() 
or BUG_ON().

Signed-off-by: Tomer Samara <tomersamar...@gmail.com>
---
 drivers/staging/android/ion/ion_page_pool.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/android/ion/ion_page_pool.c 
b/drivers/staging/android/ion/ion_page_pool.c
index 0198b886d906..ae2bc57bcbe8 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -46,11 +46,13 @@ static struct page *ion_page_pool_remove(struct 
ion_page_pool *pool, bool high)
        struct page *page;
 
        if (high) {
-               BUG_ON(!pool->high_count);
+               if (!pool->high_count)
+                       return NULL;
                page = list_first_entry(&pool->high_items, struct page, lru);
                pool->high_count--;
        } else {
-               BUG_ON(!pool->low_count);
+               if (!pool->low_count)
+                       return NULL;
                page = list_first_entry(&pool->low_items, struct page, lru);
                pool->low_count--;
        }
@@ -65,7 +67,8 @@ struct page *ion_page_pool_alloc(struct ion_page_pool *pool)
 {
        struct page *page = NULL;
 
-       BUG_ON(!pool);
+       if (!pool)
+               return NULL;
 
        mutex_lock(&pool->mutex);
        if (pool->high_count)
@@ -82,7 +85,8 @@ struct page *ion_page_pool_alloc(struct ion_page_pool *pool)
 
 void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
 {
-       BUG_ON(pool->order != compound_order(page));
+       if (pool->order != compound_order(page))
+               return;
 
        ion_page_pool_add(pool, page);
 }
@@ -124,6 +128,8 @@ int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t 
gfp_mask,
                        break;
                }
                mutex_unlock(&pool->mutex);
+               if (!page)
+                       break;
                ion_page_pool_free_pages(pool, page);
                freed += (1 << pool->order);
        }
-- 
2.25.1