[UNIX]: Move the sysctl_unix_max_dgram_qlen

This will make all the sub-namespaces always use the
default value (10) and leave the tuning via sysctl
to the init namespace only.

Per-namespace tuning is coming.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/net_namespace.h

@@ -38,6 +38,9 @@ struct net {
 	/* List of all packet sockets. */
 	rwlock_t		packet_sklist_lock;
 	struct hlist_head	packet_sklist;
+
+	/* unix sockets */
+	int			sysctl_unix_max_dgram_qlen;
 };
 
 #ifdef CONFIG_NET

net/unix/af_unix.c

@@ -117,8 +117,6 @@
 #include <net/checksum.h>
 #include <linux/security.h>
 
-int sysctl_unix_max_dgram_qlen __read_mostly = 10;
-
 static struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
 static DEFINE_SPINLOCK(unix_table_lock);
 static atomic_t unix_nr_socks = ATOMIC_INIT(0);
@@ -594,7 +592,7 @@ static struct sock * unix_create1(struct net *net, struct socket *sock)
 				&af_unix_sk_receive_queue_lock_key);
 
 	sk->sk_write_space	= unix_write_space;
-	sk->sk_max_ack_backlog	= sysctl_unix_max_dgram_qlen;
+	sk->sk_max_ack_backlog	= net->sysctl_unix_max_dgram_qlen;
 	sk->sk_destruct		= unix_sock_destructor;
 	u	  = unix_sk(sk);
 	u->dentry = NULL;
@@ -2140,6 +2138,8 @@ static int unix_net_init(struct net *net)
 {
 	int error = -ENOMEM;
 
+	net->sysctl_unix_max_dgram_qlen = 10;
+
 #ifdef CONFIG_PROC_FS
 	if (!proc_net_fops_create(net, "unix", 0, &unix_seq_fops))
 		goto out;

net/unix/sysctl_net_unix.c

@@ -18,7 +18,7 @@ static ctl_table unix_table[] = {
 	{
 		.ctl_name	= NET_UNIX_MAX_DGRAM_QLEN,
 		.procname	= "max_dgram_qlen",
-		.data		= &sysctl_unix_max_dgram_qlen,
+		.data		= &init_net.sysctl_unix_max_dgram_qlen,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec