mm: memcontrol: consolidate cgroup socket tracking

The cgroup core and the memory controller need to track socket ownership
for different purposes, but the tracking sites being entirely different
is kind of ugly.

Be a better citizen and rename the memory controller callbacks to match
the cgroup core callbacks, then move them to the same place.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20160914194846.11153-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 10 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 60bb830abc34..ae052b5e3315 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2939,16 +2939,16 @@ static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
 		/*
 		 * The active flag needs to be written after the static_key
 		 * update. This is what guarantees that the socket activation
-		 * function is the last one to run. See sock_update_memcg() for
-		 * details, and note that we don't mark any socket as belonging
-		 * to this memcg until that flag is up.
+		 * function is the last one to run. See mem_cgroup_sk_alloc()
+		 * for details, and note that we don't mark any socket as
+		 * belonging to this memcg until that flag is up.
 		 *
 		 * We need to do this, because static_keys will span multiple
 		 * sites, but we can't control their order. If we mark a socket
 		 * as accounted, but the accounting functions are not patched in
 		 * yet, we'll lose accounting.
 		 *
-		 * We never race with the readers in sock_update_memcg(),
+		 * We never race with the readers in mem_cgroup_sk_alloc(),
 		 * because when this value change, the code to process it is not
 		 * patched in yet.
 		 */
@@ -5651,11 +5651,15 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
 DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
 EXPORT_SYMBOL(memcg_sockets_enabled_key);
 
-void sock_update_memcg(struct sock *sk)
+void mem_cgroup_sk_alloc(struct sock *sk)
 {
 	struct mem_cgroup *memcg;
 
-	/* Socket cloning can throw us here with sk_cgrp already
+	if (!mem_cgroup_sockets_enabled)
+		return;
+
+	/*
+	 * Socket cloning can throw us here with sk_memcg already
 	 * filled. It won't however, necessarily happen from
 	 * process context. So the test for root memcg given
 	 * the current task's memcg won't help us in this case.
@@ -5680,12 +5684,11 @@ void sock_update_memcg(struct sock *sk)
 out:
 	rcu_read_unlock();
 }
-EXPORT_SYMBOL(sock_update_memcg);
 
-void sock_release_memcg(struct sock *sk)
+void mem_cgroup_sk_free(struct sock *sk)
 {
-	WARN_ON(!sk->sk_memcg);
-	css_put(&sk->sk_memcg->css);
+	if (sk->sk_memcg)
+		css_put(&sk->sk_memcg->css);
 }
 
 /**