net: make /proc/net/protocols namespace aware

Converting /proc/net/protocols to be namespace aware is quite easy
and permits us to use sock_prot_inuse_get().

This provides seperate counters for each protocol. For example
we can really count TCPv6 sockets and TCPv4 sockets, while previously,
we had the same value, and this value was not namespace aware.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/sock.c

@@ -2174,7 +2174,7 @@ static void proto_seq_printf(struct seq_file *seq, struct proto *proto)
 			"%2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c %2c\n",
 		   proto->name,
 		   proto->obj_size,
-		   proto->sockets_allocated != NULL ? atomic_read(proto->sockets_allocated) : -1,
+		   sock_prot_inuse_get(seq_file_net(seq), proto),
 		   proto->memory_allocated != NULL ? atomic_read(proto->memory_allocated) : -1,
 		   proto->memory_pressure != NULL ? *proto->memory_pressure ? "yes" : "no" : "NI",
 		   proto->max_header,
@@ -2228,7 +2228,8 @@ static const struct seq_operations proto_seq_ops = {
 
 static int proto_seq_open(struct inode *inode, struct file *file)
 {
-	return seq_open(file, &proto_seq_ops);
+	return seq_open_net(inode, file, &proto_seq_ops,
+			    sizeof(struct seq_net_private));
 }
 
 static const struct file_operations proto_seq_fops = {
@@ -2236,13 +2237,31 @@ static const struct file_operations proto_seq_fops = {
 	.open		= proto_seq_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= seq_release,
+	.release	= seq_release_net,
+};
+
+static __net_init int proto_init_net(struct net *net)
+{
+	if (!proc_net_fops_create(net, "protocols", S_IRUGO, &proto_seq_fops))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static __net_exit void proto_exit_net(struct net *net)
+{
+	proc_net_remove(net, "protocols");
+}
+
+
+static __net_initdata struct pernet_operations proto_net_ops = {
+	.init = proto_init_net,
+	.exit = proto_exit_net,
 };
 
 static int __init proto_init(void)
 {
-	/* register /proc/net/protocols */
-	return proc_net_fops_create(&init_net, "protocols", S_IRUGO, &proto_seq_fops) == NULL ? -ENOBUFS : 0;
+	return register_pernet_subsys(&proto_net_ops);
 }
 
 subsys_initcall(proto_init);