From: Rebecca Schultz Zavin <rebecca@android.com>
Date: Wed, 10 Oct 2012 17:34:50 +0000 (-0700)
Subject: gpu: ion: Fix lockdep issue in ion_page_pool
X-Git-Tag: firefly_0821_release~4090^2~653
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=15da191d8fdf3ebd8aed546461d17ac0714be47a;p=firefly-linux-kernel-4.4.55.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.

Change-Id: Ic1d3b2f69e61209191bac84724ba56f6b98e2bc4
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
---

diff --git a/drivers/gpu/ion/ion_page_pool.c b/drivers/gpu/ion/ion_page_pool.c
index b39663f4a1b7..3f3d2091dc82 100644
--- a/drivers/gpu/ion/ion_page_pool.c
+++ b/drivers/gpu/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);
 }