[PATCH v3 1/5] percpu: return number of released bytes from pcpu_free_area()

[Roman Gushchin <guro@fb.com>]

To implement accounting of percpu memory we need the information about the
size of freed object.  Return it from pcpu_free_area().

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Dennis Zhou <dennis@kernel.org>
---
 mm/percpu.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 696367b18222..aa36b78d45a6 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1211,11 +1211,14 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
  *
  * This function determines the size of an allocation to free using
  * the boundary bitmap and clears the allocation map.
+ *
+ * RETURNS:
+ * Number of freed bytes.
  */
-static void pcpu_free_area(struct pcpu_chunk *chunk, int off)
+static int pcpu_free_area(struct pcpu_chunk *chunk, int off)
 {
 	struct pcpu_block_md *chunk_md = &chunk->chunk_md;
-	int bit_off, bits, end, oslot;
+	int bit_off, bits, end, oslot, freed;
 
 	lockdep_assert_held(&pcpu_lock);
 	pcpu_stats_area_dealloc(chunk);
@@ -1230,8 +1233,10 @@ static void pcpu_free_area(struct pcpu_chunk *chunk, int off)
 	bits = end - bit_off;
 	bitmap_clear(chunk->alloc_map, bit_off, bits);
 
+	freed = bits * PCPU_MIN_ALLOC_SIZE;
+
 	/* update metadata */
-	chunk->free_bytes += bits * PCPU_MIN_ALLOC_SIZE;
+	chunk->free_bytes += freed;
 
 	/* update first free bit */
 	chunk_md->first_free = min(chunk_md->first_free, bit_off);
@@ -1239,6 +1244,8 @@ static void pcpu_free_area(struct pcpu_chunk *chunk, int off)
 	pcpu_block_update_hint_free(chunk, bit_off, bits);
 
 	pcpu_chunk_relocate(chunk, oslot);
+
+	return freed;
 }
 
 static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
-- 
2.26.2