android: ion: do not defer free for carveout heap

Carved out heaps allocate buffers from a memory pool of with a limited
size. If it frees buffers in deferred manner, the heap may not be
available in a rare condition by unexpected external fragmentations.
Let's think about the following scenario in a 10MB carveout pool:
  1. allocated 4MB @ +0MB
  2. allocated 2MB @ +4MB
  3. freed 1 but defferred
  4. freed 2 but defferred
  5. allocated 3MB @ +6MB
  6. returned buffer 1 and 2 to the heap.
  7. allocated 4MB @ +0MB
  8. allocation of 3MB failed due to the fragmentation.

Any defferred behavior to the very limited resources is harmful.

Change-Id: I0a64fdec56f0ec1992c20f8ccd50d5c7fbfa8d40
Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>

diff --git a/drivers/staging/android/ion/ion_carveout_heap.c b/drivers/staging/android/ion/ion_carveout_heap.c
index fee7650d6fbb391a44f24a130323e07425b4229b..dcee60b2d8136f7cc315dfbcd92337b117be6740 100644 (file)
--- a/drivers/staging/android/ion/ion_carveout_heap.c
+++ b/drivers/staging/android/ion/ion_carveout_heap.c
@@ -141,7 +141,6 @@ struct ion_heap *ion_carveout_heap_create(struct ion_platform_heap *heap_data)
                     -1);
        carveout_heap->heap.ops = &carveout_heap_ops;
        carveout_heap->heap.type = ION_HEAP_TYPE_CARVEOUT;
-       carveout_heap->heap.flags = ION_HEAP_FLAG_DEFER_FREE;
 
        return &carveout_heap->heap;
 }