hpet: simplify subdirectory registration with register_sysctl()

Patch series "sysctl: second set of kernel/sysctl cleanups", v2.

This is the 2nd set of kernel/sysctl.c cleanups.  The diff stat should
reflect how this is a much better way to deal with theses.  Fortunately
coccinelle can be used to ensure correctness for most of these and/or
future merge conflicts.

Note that since this is part of a larger effort to cleanup
kernel/sysctl.c I think we have no other option but to go with merging
these patches in either Andrew's tree or keep them staged in a separate
tree and send a merge request later.  Otherwise kernel/sysctl.c will end
up becoming a sore spot for the next merge window.

This patch (of 8):

There is no need to user boiler plate code to specify a set of base
directories we're going to stuff sysctls under.  Simplify this by using
register_sysctl() and specifying the directory path directly.

// pycocci sysctl-subdir-register-sysctl-simplify.cocci drivers/char/hpet.c

@c1@
expression E1;
identifier subdir, sysctls;
@@

static struct ctl_table subdir[] = {
	{
		.procname = E1,
		.maxlen = 0,
		.mode = 0555,
		.child = sysctls,
	},
	{ }
};

@c2@
identifier c1.subdir;

expression E2;
identifier base;
@@

static struct ctl_table base[] = {
	{
		.procname = E2,
		.maxlen = 0,
		.mode = 0555,
		.child = subdir,
	},
	{ }
};

@c3@
identifier c2.base;
identifier header;
@@

header = register_sysctl_table(base);

@r1 depends on c1 && c2 && c3@
expression c1.E1;
identifier c1.subdir, c1.sysctls;
@@

-static struct ctl_table subdir[] = {
-	{
-		.procname = E1,
-		.maxlen = 0,
-		.mode = 0555,
-		.child = sysctls,
-	},
-	{ }
-};

@r2 depends on c1 && c2 && c3@
identifier c1.subdir;

expression c2.E2;
identifier c2.base;
@@
-static struct ctl_table base[] = {
-	{
-		.procname = E2,
-		.maxlen = 0,
-		.mode = 0555,
-		.child = subdir,
-	},
-	{ }
-};

@initialize:python@
@@

def make_my_fresh_expression(s1, s2):
  return '"' + s1.strip('"') + "/" + s2.strip('"') + '"'

@r3 depends on c1 && c2 && c3@
expression c1.E1;
identifier c1.sysctls;
expression c2.E2;
identifier c2.base;
identifier c3.header;
fresh identifier E3 = script:python(E2, E1) { make_my_fresh_expression(E2, E1) };
@@

header =
-register_sysctl_table(base);
+register_sysctl(E3, sysctls);

Generated-by: Coccinelle SmPL

Link: https://lkml.kernel.org/r/20211123202422.819032-1-mcgrof@kernel.org
Link: https://lkml.kernel.org/r/20211123202422.819032-2-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qing Wang <wangqing@vivo.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: James E.J. Bottomley <jejb@linux.ibm.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
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/hpet.c

@@ -746,26 +746,6 @@ static struct ctl_table hpet_table[] = {
 	{}
 };
 
-static struct ctl_table hpet_root[] = {
-	{
-	 .procname = "hpet",
-	 .maxlen = 0,
-	 .mode = 0555,
-	 .child = hpet_table,
-	 },
-	{}
-};
-
-static struct ctl_table dev_root[] = {
-	{
-	 .procname = "dev",
-	 .maxlen = 0,
-	 .mode = 0555,
-	 .child = hpet_root,
-	 },
-	{}
-};
-
 static struct ctl_table_header *sysctl_header;
 
 /*
@@ -1061,7 +1041,7 @@ static int __init hpet_init(void)
 	if (result < 0)
 		return -ENODEV;
 
-	sysctl_header = register_sysctl_table(dev_root);
+	sysctl_header = register_sysctl("dev/hpet", hpet_table);
 
 	result = acpi_bus_register_driver(&hpet_acpi_driver);
 	if (result < 0) {