staging: ion: Move shrinker out of heaps

Every heap that uses deferred frees is going to need a shrinker
to shrink the freelist under memory pressure.  Rather than
requiring each heap to implement a shrinker, automatically
register a shrinker if the deferred free flag is set.
The system heap also needs to shrink its page pools, so add
a shrink function to the heap ops that will be called after
shrinking the freelists.

Cc: Colin Cross <ccross@android.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Colin Cross <ccross@android.com>
[jstultz: Resolved big conflicts with the shrinker api change.
Also minor commit subject tweak.]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/staging/android/ion/ion_heap.c b/drivers/staging/android/ion/ion_heap.c
index 305b75ed6385..49ace13ac545 100644
--- a/drivers/staging/android/ion/ion_heap.c
+++ b/drivers/staging/android/ion/ion_heap.c
@@ -252,6 +252,56 @@ int ion_heap_init_deferred_free(struct ion_heap *heap)
 	return 0;
 }
 
+static unsigned long ion_heap_shrink_count(struct shrinker *shrinker,
+						struct shrink_control *sc)
+{
+	struct ion_heap *heap = container_of(shrinker, struct ion_heap,
+					     shrinker);
+	int total = 0;
+
+	total = ion_heap_freelist_size(heap) / PAGE_SIZE;
+	if (heap->ops->shrink)
+		total += heap->ops->shrink(heap, sc->gfp_mask, 0);
+	return total;
+}
+
+static unsigned long ion_heap_shrink_scan(struct shrinker *shrinker,
+						struct shrink_control *sc)
+{
+	struct ion_heap *heap = container_of(shrinker, struct ion_heap,
+					     shrinker);
+	int freed = 0;
+	int to_scan = sc->nr_to_scan;
+
+	if (to_scan == 0)
+		return 0;
+
+	/*
+	 * shrink the free list first, no point in zeroing the memory if we're
+	 * just going to reclaim it
+	 */
+	if (heap->flags & ION_HEAP_FLAG_DEFER_FREE)
+		freed = ion_heap_freelist_drain(heap, to_scan * PAGE_SIZE) /
+				PAGE_SIZE;
+
+	to_scan -= freed;
+	if (to_scan <= 0)
+		return freed;
+
+	if (heap->ops->shrink)
+		freed += heap->ops->shrink(heap, sc->gfp_mask, to_scan);
+	return freed;
+}
+
+void 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);
+}
+
 struct ion_heap *ion_heap_create(struct ion_platform_heap *heap_data)
 {
 	struct ion_heap *heap = NULL;