staging: android: check for error from register_shrinker in ion_heap_init_shrinker

The function register_shrinker in ion_heap_init_shrinker may return an
error, check it out. Meanwhile, ion_heap_init_shrinker has to a return
value.
Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/ion/ion.c

@@ -529,6 +529,7 @@ void ion_device_add_heap(struct ion_heap *heap)
 {
 	struct dentry *debug_file;
 	struct ion_device *dev = internal_dev;
+	int ret;
 
 	if (!heap->ops->allocate || !heap->ops->free)
 		pr_err("%s: can not add heap with invalid ops struct.\n",
@@ -540,8 +541,11 @@ void ion_device_add_heap(struct ion_heap *heap)
 	if (heap->flags & ION_HEAP_FLAG_DEFER_FREE)
 		ion_heap_init_deferred_free(heap);
 
-	if ((heap->flags & ION_HEAP_FLAG_DEFER_FREE) || heap->ops->shrink)
-		ion_heap_init_shrinker(heap);
+	if ((heap->flags & ION_HEAP_FLAG_DEFER_FREE) || heap->ops->shrink) {
+		ret = ion_heap_init_shrinker(heap);
+		if (ret)
+			pr_err("%s: Failed to register shrinker\n", __func__);
+	}
 
 	heap->dev = dev;
 	down_write(&dev->lock);

drivers/staging/android/ion/ion.h

@@ -230,7 +230,7 @@ int ion_alloc(size_t len,
  * this function will be called to setup a shrinker to shrink the freelists
  * and call the heap's shrink op.
  */
-void ion_heap_init_shrinker(struct ion_heap *heap);
+int ion_heap_init_shrinker(struct ion_heap *heap);
 
 /**
  * ion_heap_init_deferred_free -- initialize deferred free functionality

drivers/staging/android/ion/ion_heap.c

@@ -297,11 +297,12 @@ static unsigned long ion_heap_shrink_scan(struct shrinker *shrinker,
 	return freed;
 }
 
-void ion_heap_init_shrinker(struct ion_heap *heap)
+int ion_heap_init_shrinker(struct ion_heap *heap)
 {
 	heap->shrinker.count_objects = ion_heap_shrink_count;
 	heap->shrinker.scan_objects = ion_heap_shrink_scan;
 	heap->shrinker.seeks = DEFAULT_SEEKS;
 	heap->shrinker.batch = 0;
-	register_shrinker(&heap->shrinker);
+
+	return register_shrinker(&heap->shrinker);
 }