net: tcp_memcontrol: remove dead per-memcg count of allocated sockets

The number of allocated sockets is used for calculations in the soft
limit phase, where packets are accepted but the socket is under memory
pressure.
 Since there is no soft limit phase in tcp_memcontrol, and memory
pressure is only entered when packets are already dropped, this is
actually dead code.  Remove it.

As this is the last user of parent_cg_proto(), remove that too.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/net/sock.h b/include/net/sock.h
index d3b035c..1f15937 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1098,19 +1098,9 @@
 
 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_NET)
 extern struct static_key memcg_socket_limit_enabled;
-static inline struct cg_proto *parent_cg_proto(struct proto *proto,
-					       struct cg_proto *cg_proto)
-{
-	return proto->proto_cgroup(parent_mem_cgroup(cg_proto->memcg));
-}
 #define mem_cgroup_sockets_enabled static_key_false(&memcg_socket_limit_enabled)
 #else
 #define mem_cgroup_sockets_enabled 0
-static inline struct cg_proto *parent_cg_proto(struct proto *proto,
-					       struct cg_proto *cg_proto)
-{
-	return NULL;
-}
 #endif
 
 static inline bool sk_stream_memory_free(const struct sock *sk)
@@ -1236,41 +1226,18 @@
 
 static inline void sk_sockets_allocated_dec(struct sock *sk)
 {
-	struct proto *prot = sk->sk_prot;
-
-	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
-		struct cg_proto *cg_proto = sk->sk_cgrp;
-
-		for (; cg_proto; cg_proto = parent_cg_proto(prot, cg_proto))
-			percpu_counter_dec(&cg_proto->sockets_allocated);
-	}
-
-	percpu_counter_dec(prot->sockets_allocated);
+	percpu_counter_dec(sk->sk_prot->sockets_allocated);
 }
 
 static inline void sk_sockets_allocated_inc(struct sock *sk)
 {
-	struct proto *prot = sk->sk_prot;
-
-	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
-		struct cg_proto *cg_proto = sk->sk_cgrp;
-
-		for (; cg_proto; cg_proto = parent_cg_proto(prot, cg_proto))
-			percpu_counter_inc(&cg_proto->sockets_allocated);
-	}
-
-	percpu_counter_inc(prot->sockets_allocated);
+	percpu_counter_inc(sk->sk_prot->sockets_allocated);
 }
 
 static inline int
 sk_sockets_allocated_read_positive(struct sock *sk)
 {
-	struct proto *prot = sk->sk_prot;
-
-	if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
-		return percpu_counter_read_positive(&sk->sk_cgrp->sockets_allocated);
-
-	return percpu_counter_read_positive(prot->sockets_allocated);
+	return percpu_counter_read_positive(sk->sk_prot->sockets_allocated);
 }
 
 static inline int