memcg: move memcg_proto_active from sock.h

The only user is sock_update_memcg which is living in memcontrol.c so it
doesn't make much sense to pollute sock.h by this inline helper.  Move it
to memcontrol.c and open code it into its only caller.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/net/sock.h

@@ -1045,11 +1045,6 @@ struct proto {
 int proto_register(struct proto *prot, int alloc_slab);
 void proto_unregister(struct proto *prot);
 
-static inline bool memcg_proto_active(struct cg_proto *cg_proto)
-{
-	return test_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
-}
-
 #ifdef SOCK_REFCNT_DEBUG
 static inline void sk_refcnt_debug_inc(struct sock *sk)
 {

mm/memcontrol.c

@@ -315,7 +315,7 @@ void sock_update_memcg(struct sock *sk)
 		rcu_read_lock();
 		memcg = mem_cgroup_from_task(current);
 		cg_proto = sk->sk_prot->proto_cgroup(memcg);
-		if (cg_proto && memcg_proto_active(cg_proto) &&
+		if (cg_proto && test_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags) &&
 		    css_tryget_online(&memcg->css)) {
 			sk->sk_cgrp = cg_proto;
 		}