scsi/sg: move sg-big-buff sysctl to scsi/sg.c

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 sg-big-buff sysctl from kernel/sysctl.c to drivers/scsi/sg.c
and use register_sysctl() to register the sysctl interface.

[[email protected]: commit log update]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Xiaoming Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Amir Goldstein <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Antti Palosaari <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Benjamin LaHaise <[email protected]>
Cc: Clemens Ladisch <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Douglas Gilbert <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Iurii Zaikin <[email protected]>
Cc: James E.J. Bottomley <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: John Ogness <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Joseph Qi <[email protected]>
Cc: Julia Lawall <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Lukas Middendorf <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Martin K. Petersen <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Phillip Potter <[email protected]>
Cc: Qing Wang <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Sebastian Reichel <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Stephen Kitt <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

3 files changed, 34 insertions, 17 deletions

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index ad12b3261845..6b43e97bd417 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -77,7 +77,7 @@ static int sg_proc_init(void);
 
 #define SG_DEFAULT_TIMEOUT mult_frac(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
 
-int sg_big_buff = SG_DEF_RESERVED_SIZE;
+static int sg_big_buff = SG_DEF_RESERVED_SIZE;
 /* N.B. This variable is readable and writeable via
    /proc/scsi/sg/def_reserved_size . Each time sg_open() is called a buffer
    of this size (or less if there is not enough memory) will be reserved
@@ -1634,6 +1634,37 @@ MODULE_PARM_DESC(scatter_elem_sz, "scatter gather element "
 MODULE_PARM_DESC(def_reserved_size, "size of buffer reserved for each fd");
 MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow))");
 
+#ifdef CONFIG_SYSCTL
+#include <linux/sysctl.h>
+
+static struct ctl_table sg_sysctls[] = {
+	{
+		.procname	= "sg-big-buff",
+		.data		= &sg_big_buff,
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.proc_handler	= proc_dointvec,
+	},
+	{}
+};
+
+static struct ctl_table_header *hdr;
+static void register_sg_sysctls(void)
+{
+	if (!hdr)
+		hdr = register_sysctl("kernel", sg_sysctls);
+}
+
+static void unregister_sg_sysctls(void)
+{
+	if (hdr)
+		unregister_sysctl_table(hdr);
+}
+#else
+#define register_sg_sysctls() do { } while (0)
+#define unregister_sg_sysctls() do { } while (0)
+#endif /* CONFIG_SYSCTL */
+
 static int __init
 init_sg(void)
 {
@@ -1666,6 +1697,7 @@ init_sg(void)
 		return 0;
 	}
 	class_destroy(sg_sysfs_class);
+	register_sg_sysctls();
 err_out:
 	unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), SG_MAX_DEVS);
 	return rc;
@@ -1674,6 +1706,7 @@ err_out:
 static void __exit
 exit_sg(void)
 {
+	unregister_sg_sysctls();
 #ifdef CONFIG_SCSI_PROC_FS
 	remove_proc_subtree("scsi/sg", NULL);
 #endif				/* CONFIG_SCSI_PROC_FS */
diff --git a/include/scsi/sg.h b/include/scsi/sg.h
index 843cefb8efce..068e35d36557 100644
--- a/include/scsi/sg.h
+++ b/include/scsi/sg.h
@@ -29,10 +29,6 @@
  * For utility and test programs see: http://sg.danny.cz/sg/sg3_utils.html
  */
 
-#ifdef __KERNEL__
-extern int sg_big_buff; /* for sysctl */
-#endif
-
 
 typedef struct sg_iovec /* same structure as used by readv() Linux system */
 {                       /* call. It defines one scatter-gather element. */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 509f782483db..b0cced3808d4 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -95,9 +95,6 @@
 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_LOCK_STAT)
 #include <linux/lockdep.h>
 #endif
-#ifdef CONFIG_CHR_DEV_SG
-#include <scsi/sg.h>
-#endif
 #ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
 #include <linux/stackleak.h>
 #endif
@@ -2090,15 +2087,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dostring,
 	},
 #endif
-#ifdef CONFIG_CHR_DEV_SG
-	{
-		.procname	= "sg-big-buff",
-		.data		= &sg_big_buff,
-		.maxlen		= sizeof (int),
-		.mode		= 0444,
-		.proc_handler	= proc_dointvec,
-	},
-#endif
 #ifdef CONFIG_BSD_PROCESS_ACCT
 	{
 		.procname	= "acct",