[PATCH 3/3] mm/memcg: move generation assignment and comparison together

[Wei Yang <richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

For each round-trip, we assign generation on first invocation and
compare it on subsequent invocations.

Let's move them together to make it more self-explaining. Also this
reduce a check on prev.

Signed-off-by: Wei Yang <richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 mm/memcontrol.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 03399146168f..17da93c2f94e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -996,7 +996,14 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 		mz = root->nodeinfo[reclaim->pgdat->node_id];
 		iter = &mz->iter;
 
-		if (prev && reclaim->generation != iter->generation)
+		/*
+		 * On first invocation, assign iter->generation to
+		 * reclaim->generation.
+		 * On subsequent invocations, make sure no one else jump in.
+		 */
+		if (!prev)
+			reclaim->generation = iter->generation;
+		else if (reclaim->generation != iter->generation)
 			goto out_unlock;
 
 		while (1) {
@@ -1056,8 +1063,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 
 		if (!memcg)
 			iter->generation++;
-		else if (!prev)
-			reclaim->generation = iter->generation;
 	}
 
 out_unlock:
-- 
2.33.1