sysctl: simplify the pty sysctl logic

Instead of having a bunch of ifdefs in sysctl.c move all of the pty sysctl
logic into drivers/char/pty.c

As well as cleaning up the logic this prevents sysctl_check_table from
complaining that the root table has a NULL data pointer on something with
generic methods.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/pty.c

@@ -318,7 +318,7 @@ int pty_limit = NR_UNIX98_PTY_DEFAULT;
 static int pty_limit_min = 0;
 static int pty_limit_max = NR_UNIX98_PTY_MAX;
 
-ctl_table pty_table[] = {
+static struct ctl_table pty_table[] = {
 	{
 		.ctl_name	= PTY_MAX,
 		.procname	= "max",
@@ -340,6 +340,27 @@ ctl_table pty_table[] = {
 	}
 };
 
+static struct ctl_table pty_kern_table[] = {
+	{
+		.ctl_name	= KERN_PTY,
+		.procname	= "pty",
+		.mode		= 0555,
+		.child		= pty_table,
+	},
+	{}
+};
+
+static struct ctl_table pty_root_table[] = {
+	{
+		.ctl_name	= CTL_KERN,
+		.procname	= "kernel",
+		.mode		= 0555,
+		.child		= pty_kern_table,
+	},
+	{}
+};
+
+
 static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
 			    unsigned int cmd, unsigned long arg)
 {
@@ -404,6 +425,7 @@ static void __init unix98_pty_init(void)
 		panic("Couldn't register Unix98 pts driver");
 
 	pty_table[1].data = &ptm_driver->refcount;
+	register_sysctl_table(pty_root_table);
 }
 #else
 static inline void unix98_pty_init(void) { }

kernel/sysctl.c

@@ -163,9 +163,6 @@ static struct ctl_table fs_table[];
 static struct ctl_table debug_table[];
 static struct ctl_table dev_table[];
 extern struct ctl_table random_table[];
-#ifdef CONFIG_UNIX98_PTYS
-extern struct ctl_table pty_table[];
-#endif
 #ifdef CONFIG_INOTIFY_USER
 extern struct ctl_table inotify_table[];
 #endif
@@ -534,14 +531,6 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0555,
 		.child		= random_table,
 	},
-#ifdef CONFIG_UNIX98_PTYS
-	{
-		.ctl_name	= KERN_PTY,
-		.procname	= "pty",
-		.mode		= 0555,
-		.child		= pty_table,
-	},
-#endif
 	{
 		.ctl_name	= KERN_OVERFLOWUID,
 		.procname	= "overflowuid",