linux-kernel - [PATCH v2 8/8] sysctl: share unsigned long const values

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Message-Id: <20211124231435.1445213-9-mcgrof@kernel.org>
Date:   Wed, 24 Nov 2021 15:14:35 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     akpm@...ux-foundation.org, keescook@...omium.org,
        yzaikin@...gle.com, nixiaoming@...wei.com, ebiederm@...ssion.com,
        steve@....org, gregkh@...uxfoundation.org, rafael@...nel.org,
        tytso@....edu, viro@...iv.linux.org.uk, pmladek@...e.com,
        senozhatsky@...omium.org, rostedt@...dmis.org,
        john.ogness@...utronix.de, dgilbert@...erlog.com,
        jejb@...ux.ibm.com, martin.petersen@...cle.com,
        mcgrof@...badil.infradead.org, mcgrof@...nel.org,
        linux-scsi@...r.kernel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 8/8] sysctl: share unsigned long const values

Provide a way to share unsigned long values.
This will allow others to not have to re-invent
these values.

Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 fs/proc/proc_sysctl.c  | 3 +++
 include/linux/sysctl.h | 6 ++++++
 kernel/sysctl.c        | 9 +++------
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index aa743bbb8400..2b73648a19a5 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -29,6 +29,9 @@ static const struct inode_operations proc_sys_dir_operations;
 const int sysctl_vals[] = { -1, 0, 1, 2, 4, 100, 200, 1000, INT_MAX };
 EXPORT_SYMBOL(sysctl_vals);
 
+const unsigned long sysctl_long_vals[] = { 0, 1, LONG_MAX };
+EXPORT_SYMBOL_GPL(sysctl_long_vals);
+
 /* Support for permanently empty directories */
 
 struct ctl_table sysctl_mount_point[] = {
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 7946b532e964..162aaee92daf 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -50,6 +50,12 @@ struct ctl_dir;
 
 extern const int sysctl_vals[];
 
+#define SYSCTL_LONG_ZERO	((void *)&sysctl_long_vals[0])
+#define SYSCTL_LONG_ONE		((void *)&sysctl_long_vals[1])
+#define SYSCTL_LONG_MAX		((void *)&sysctl_long_vals[2])
+
+extern const unsigned long sysctl_long_vals[];
+
 typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
 		size_t *lenp, loff_t *ppos);
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 5812d76ecee1..b8a3dcf7b925 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -99,9 +99,6 @@
 
 /* Constants used for minimum and  maximum */
 
-static const unsigned long zero_ul;
-static const unsigned long one_ul = 1;
-static const unsigned long long_max = LONG_MAX;
 #ifdef CONFIG_PRINTK
 static const int ten_thousand = 10000;
 #endif
@@ -2512,7 +2509,7 @@ static struct ctl_table vm_table[] = {
 		.maxlen		= sizeof(dirty_background_bytes),
 		.mode		= 0644,
 		.proc_handler	= dirty_background_bytes_handler,
-		.extra1		= (void *)&one_ul,
+		.extra1		= SYSCTL_LONG_ONE,
 	},
 	{
 		.procname	= "dirty_ratio",
@@ -2930,8 +2927,8 @@ static struct ctl_table fs_table[] = {
 		.maxlen		= sizeof(files_stat.max_files),
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
-		.extra1		= (void *)&zero_ul,
-		.extra2		= (void *)&long_max,
+		.extra1		= SYSCTL_LONG_ZERO,
+		.extra2		= SYSCTL_LONG_MAX,
 	},
 	{
 		.procname	= "nr_open",
-- 
2.33.0