[next -v1 4/5] memcg: factor out the __refill_obj_stock function

[Chen Ridong]

From: Chen Ridong <chenridong@xxxxxxxxxx>

Factor out the '__refill_obj_stock' function to make the code more
cohesive.

Signed-off-by: Chen Ridong <chenridong@xxxxxxxxxx>
---
 mm/memcontrol.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f977e0be1c04..0c9331d7b606 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2697,6 +2697,21 @@ void __memcg_kmem_uncharge_page(struct page *page, int order)
 	obj_cgroup_put(objcg);
 }
 
+/* If the cached_objcg was refilled, return true; otherwise, return false */
+static bool __refill_obj_stock(struct memcg_stock_pcp *stock,
+		struct obj_cgroup *objcg, struct obj_cgroup **old_objcg)
+{
+	if (READ_ONCE(stock->cached_objcg) != objcg) {
+		*old_objcg = drain_obj_stock(stock);
+		obj_cgroup_get(objcg);
+		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
+				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
+		WRITE_ONCE(stock->cached_objcg, objcg);
+		return true;
+	}
+	return false;
+}
+
 static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
 		     enum node_stat_item idx, int nr)
 {
@@ -2713,12 +2728,7 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
 	 * accumulating over a page of vmstat data or when pgdat or idx
 	 * changes.
 	 */
-	if (READ_ONCE(stock->cached_objcg) != objcg) {
-		old = drain_obj_stock(stock);
-		obj_cgroup_get(objcg);
-		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
-				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
-		WRITE_ONCE(stock->cached_objcg, objcg);
+	if (__refill_obj_stock(stock, objcg, &old)) {
 		stock->cached_pgdat = pgdat;
 	} else if (stock->cached_pgdat != pgdat) {
 		/* Flush the existing cached vmstat data */
@@ -2871,14 +2881,9 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
 	local_lock_irqsave(&memcg_stock.stock_lock, flags);
 
 	stock = this_cpu_ptr(&memcg_stock);
-	if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */
-		old = drain_obj_stock(stock);
-		obj_cgroup_get(objcg);
-		WRITE_ONCE(stock->cached_objcg, objcg);
-		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
-				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
+	if (__refill_obj_stock(stock, objcg, &old))
 		allow_uncharge = true;	/* Allow uncharge when objcg changes */
-	}
+
 	stock->nr_bytes += nr_bytes;
 
 	if (allow_uncharge && (stock->nr_bytes > PAGE_SIZE)) {
-- 
2.34.1