random: move the random sysctl declarations to its own file

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

So move the random sysctls to their own file and use
register_sysctl_init().

[mcgrof@kernel.org: commit log update to justify the move]

Link: https://lkml.kernel.org/r/20211124231435.1445213-3-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Qing Wang <wangqing@vivo.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/random.c

@@ -1992,8 +1992,7 @@ static int proc_do_entropy(struct ctl_table *table, int write, void *buffer,
 }
 
 static int sysctl_poolsize = POOL_BITS;
-extern struct ctl_table random_table[];
-struct ctl_table random_table[] = {
+static struct ctl_table random_table[] = {
 	{
 		.procname	= "poolsize",
 		.data		= &sysctl_poolsize,
@@ -2055,6 +2054,17 @@ struct ctl_table random_table[] = {
 #endif
 	{ }
 };
+
+/*
+ * rand_initialize() is called before sysctl_init(),
+ * so we cannot call register_sysctl_init() in rand_initialize()
+ */
+static int __init random_sysctls_init(void)
+{
+	register_sysctl_init("kernel/random", random_table);
+	return 0;
+}
+device_initcall(random_sysctls_init);
 #endif	/* CONFIG_SYSCTL */
 
 struct batched_entropy {

include/linux/sysctl.h

@@ -217,7 +217,6 @@ extern int unaligned_dump_stack;
 extern int no_unaligned_warning;
 
 extern struct ctl_table sysctl_mount_point[];
-extern struct ctl_table random_table[];
 
 #else /* CONFIG_SYSCTL */
 static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)

kernel/sysctl.c

@@ -2144,11 +2144,6 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= sysctl_max_threads,
 	},
-	{
-		.procname	= "random",
-		.mode		= 0555,
-		.child		= random_table,
-	},
 	{
 		.procname	= "usermodehelper",
 		.mode		= 0555,