linux-kernel - [PATCH 06/14] net: tcp_memcontrol: remove dead per-memcg count of allocated sockets

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Date:	Thu, 12 Nov 2015 18:41:25 -0500
From:	Johannes Weiner <hannes@...xchg.org>
To:	David Miller <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Vladimir Davydov <vdavydov@...tuozzo.com>,
	Tejun Heo <tj@...nel.org>, Michal Hocko <mhocko@...e.cz>,
	netdev@...r.kernel.org, linux-mm@...ck.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-team@...com
Subject: [PATCH 06/14] 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@...xchg.org>
---
 include/linux/memcontrol.h |  1 -
 include/net/sock.h         | 39 +++------------------------------------
 net/ipv4/tcp_memcontrol.c  |  3 ---
 3 files changed, 3 insertions(+), 40 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e930803..185df8c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -97,7 +97,6 @@ enum cg_proto_flags {
 
 struct cg_proto {
 	struct page_counter	memory_allocated;	/* Current allocated memory. */
-	struct percpu_counter	sockets_allocated;	/* Current number of sockets. */
 	int			memory_pressure;
 	long			sysctl_mem[3];
 	unsigned long		flags;
diff --git a/include/net/sock.h b/include/net/sock.h
index 6fc9147..ed141b3 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1095,19 +1095,9 @@ static inline void sk_refcnt_debug_release(const struct sock *sk)
 
 #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)
@@ -1233,41 +1223,18 @@ sk_memory_allocated_sub(struct sock *sk, int amt)
 
 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
diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index 2379c1b..8965638 100644
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -32,7 +32,6 @@ int tcp_init_cgroup(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 		counter_parent = &parent_cg->memory_allocated;
 
 	page_counter_init(&cg_proto->memory_allocated, counter_parent);
-	percpu_counter_init(&cg_proto->sockets_allocated, 0, GFP_KERNEL);
 
 	return 0;
 }
@@ -46,8 +45,6 @@ void tcp_destroy_cgroup(struct mem_cgroup *memcg)
 	if (!cg_proto)
 		return;
 
-	percpu_counter_destroy(&cg_proto->sockets_allocated);
-
 	if (test_bit(MEMCG_SOCK_ACTIVATED, &cg_proto->flags))
 		static_key_slow_dec(&memcg_socket_limit_enabled);
 
-- 
2.6.2

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