[NETNS]: struct net content re-work (v3)

Recently David Miller and Herbert Xu pointed out that struct net becomes
overbloated and un-maintainable. There are two solutions:
- provide a pointer to a network subsystem definition from struct net.
This costs an additional dereferrence
- place sub-system definition into the structure itself. This will speedup
run-time access at the cost of recompilation time

The second approach looks better for us. Other sub-systems will follow.

Signed-off-by: Denis V. Lunev <[e-mail]>
Acked-by: Daniel Lezcano <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/net_namespace.h

···
 #include <linux/workqueue.h>
 #include <linux/list.h>
 
+#include <net/netns/unix.h>
+
 struct proc_dir_entry;
 struct net_device;
 struct sock;
···
 	rwlock_t		packet_sklist_lock;
 	struct hlist_head	packet_sklist;
 
-	/* unix sockets */
-	int			sysctl_unix_max_dgram_qlen;
-	struct ctl_table_header	*unix_ctl;
+	struct netns_unix	unx;
 };
 
 #ifdef CONFIG_NET

include/net/netns/unix.h

···
+/*
+ * Unix network namespace
+ */
+#ifndef __NETNS_UNIX_H__
+#define __NETNS_UNIX_H__
+
+struct ctl_table_header;
+struct netns_unix {
+	int			sysctl_max_dgram_qlen;
+	struct ctl_table_header	*ctl;
+};
+
+#endif /* __NETNS_UNIX_H__ */

net/unix/af_unix.c

···
 				&af_unix_sk_receive_queue_lock_key);
 
 	sk->sk_write_space	= unix_write_space;
-	sk->sk_max_ack_backlog	= net->sysctl_unix_max_dgram_qlen;
+	sk->sk_max_ack_backlog	= net->unx.sysctl_max_dgram_qlen;
 	sk->sk_destruct		= unix_sock_destructor;
 	u	  = unix_sk(sk);
 	u->dentry = NULL;
···
 {
 	int error = -ENOMEM;
 
-	net->sysctl_unix_max_dgram_qlen = 10;
+	net->unx.sysctl_max_dgram_qlen = 10;
 	if (unix_sysctl_register(net))
 		goto out;
 

net/unix/sysctl_net_unix.c

···
 	{
 		.ctl_name	= NET_UNIX_MAX_DGRAM_QLEN,
 		.procname	= "max_dgram_qlen",
-		.data		= &init_net.sysctl_unix_max_dgram_qlen,
+		.data		= &init_net.unx.sysctl_max_dgram_qlen,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec
···
 	if (table == NULL)
 		goto err_alloc;
 
-	table[0].data = &net->sysctl_unix_max_dgram_qlen;
-	net->unix_ctl = register_net_sysctl_table(net, unix_path, table);
-	if (net->unix_ctl == NULL)
+	table[0].data = &net->unx.sysctl_max_dgram_qlen;
+	net->unx.ctl = register_net_sysctl_table(net, unix_path, table);
+	if (net->unx.ctl == NULL)
 		goto err_reg;
 
 	return 0;
···
 {
 	struct ctl_table *table;
 
-	table = net->unix_ctl->ctl_table_arg;
-	unregister_sysctl_table(net->unix_ctl);
+	table = net->unx.ctl->ctl_table_arg;
+	unregister_sysctl_table(net->unx.ctl);
 	kfree(table);
 }