Re: [PATCH v2 6/9] per-cgroup tcp buffers control

+#ifdef CONFIG_INET
+#include <net/sock.h>
+static inline void sock_update_kmem_cgrp(struct sock *sk)
+{
+#ifdef CONFIG_CGROUP_KMEM
+	sk->sk_cgrp = kcg_from_task(current);
+
+	/*
+	 * We don't need to protect against anything task-related, because
+	 * we are basically stuck with the sock pointer that won't change,
+	 * even if the task that originated the socket changes cgroups.
+	 *
+	 * What we do have to guarantee, is that the chain leading us to
+	 * the top level won't change under our noses. Incrementing the
+	 * reference count via cgroup_exclude_rmdir guarantees that.
+	 */
+	cgroup_exclude_rmdir(&sk->sk_cgrp->css);
+#endif

+}
+
+static inline void sock_release_kmem_cgrp(struct sock *sk)
+{
+#ifdef CONFIG_CGROUP_KMEM
+	cgroup_release_and_wakeup_rmdir(&sk->sk_cgrp->css);
+#endif
+}

+
+#endif /* CONFIG_INET */
 #endif /* _LINUX_KMEM_CGROUP_H */
 

diff --git a/include/net/sock.h b/include/net/sock.h
index 8e4062f..709382f 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h

@@ -228,6 +228,7 @@ struct sock_common {
   *	@sk_security: used by security modules
   *	@sk_mark: generic packet mark
   *	@sk_classid: this socket's cgroup classid
+  *	@sk_cgrp: this socket's kernel memory (kmem) cgroup 
   *	@sk_write_pending: a write to stream socket waits to start
   *	@sk_state_change: callback to indicate change in the state of the sock
   *	@sk_data_ready: callback to indicate there is data to be processed

@@ -339,6 +340,7 @@ struct sock {
 #endif
 	__u32			sk_mark;
 	u32			sk_classid;
+	struct kmem_cgroup	*sk_cgrp;
 	void			(*sk_state_change)(struct sock *sk);
 	void			(*sk_data_ready)(struct sock *sk, int bytes);
 	void			(*sk_write_space)(struct sock *sk);

diff --git a/net/core/sock.c b/net/core/sock.c
index 3449df8..7109864 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c

@@ -1139,6 +1139,7 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
 		atomic_set(&sk->sk_wmem_alloc, 1);
 
 		sock_update_classid(sk);
+		sock_update_kmem_cgrp(sk);
 	}
 
 	return sk;

@@ -1170,6 +1171,7 @@ static void __sk_free(struct sock *sk)
 		put_cred(sk->sk_peer_cred);
 	put_pid(sk->sk_peer_pid);
 	put_net(sock_net(sk));
+	sock_release_kmem_cgrp(sk);
 	sk_prot_free(sk->sk_prot_creator, sk);
 }
 

@@ -2252,9 +2254,6 @@ void sk_common_release(struct sock *sk)
 }
 EXPORT_SYMBOL(sk_common_release);
 
-static DEFINE_RWLOCK(proto_list_lock);
-static LIST_HEAD(proto_list);
-