From: Rebecca Schultz Zavin <rebecca@android.com>
Date: Fri, 13 Dec 2013 22:24:14 +0000 (-0800)
Subject: gpu: ion: Fix lockdep issue in ion_page_pool
X-Git-Tag: next-20131220~15^2~204
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=efee5a0c62d827c0eca7044c2d14dd3324b325aa;p=karo-tx-linux.git

gpu: ion: Fix lockdep issue in ion_page_pool

Currently the mutex is held while kmalloc is called, under a low memory
condition this might trigger the shrinker which also takes this mutex.
Refactor so the mutex is not held during allocation.

Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
[jstultz: modified patch to apply to staging directory]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index ea45380d748c..20790eb18c7d 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -53,6 +53,8 @@ static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
 	item = kmalloc(sizeof(struct ion_page_pool_item), GFP_KERNEL);
 	if (!item)
 		return -ENOMEM;
+
+	mutex_lock(&pool->mutex);
 	item->page = page;
 	if (PageHighMem(page)) {
 		list_add_tail(&item->list, &pool->high_items);
@@ -61,6 +63,7 @@ static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
 		list_add_tail(&item->list, &pool->low_items);
 		pool->low_count++;
 	}
+	mutex_unlock(&pool->mutex);
 	return 0;
 }
 
@@ -110,9 +113,7 @@ void ion_page_pool_free(struct ion_page_pool *pool, struct page* page)
 {
 	int ret;
 
-	mutex_lock(&pool->mutex);
 	ret = ion_page_pool_add(pool, page);
-	mutex_unlock(&pool->mutex);
 	if (ret)
 		ion_page_pool_free_pages(pool, page);
 }