From: Luis Chamberlain <mcgrof@xxxxxxxxxx> Subject: 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. Link: https://lkml.kernel.org/r/20211124231435.1445213-9-mcgrof@xxxxxxxxxx Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Amir Goldstein <amir73il@xxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Antti Palosaari <crope@xxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Benjamin LaHaise <bcrl@xxxxxxxxx> Cc: Clemens Ladisch <clemens@xxxxxxxxxx> Cc: David Airlie <airlied@xxxxxxxx> Cc: Douglas Gilbert <dgilbert@xxxxxxxxxxxx> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Iurii Zaikin <yzaikin@xxxxxxxxxx> Cc: James E.J. Bottomley <jejb@xxxxxxxxxxxxx> Cc: Jani Nikula <jani.nikula@xxxxxxxxx> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Joel Becker <jlbec@xxxxxxxxxxxx> Cc: John Ogness <john.ogness@xxxxxxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> Cc: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> Cc: Julia Lawall <julia.lawall@xxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Lukas Middendorf <kernel@xxxxxxxxxxx> Cc: Mark Fasheh <mark@xxxxxxxxxx> Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Cc: Paul Turner <pjt@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Phillip Potter <phil@xxxxxxxxxxxxxxxx> Cc: Qing Wang <wangqing@xxxxxxxx> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> Cc: Sebastian Reichel <sre@xxxxxxxxxx> Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> Cc: Stephen Kitt <steve@xxxxxxx> Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Cc: "Theodore Ts'o" <tytso@xxxxxxx> Cc: Xiaoming Ni <nixiaoming@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/proc_sysctl.c | 3 +++ include/linux/sysctl.h | 6 ++++++ kernel/sysctl.c | 9 +++------ 3 files changed, 12 insertions(+), 6 deletions(-) --- a/fs/proc/proc_sysctl.c~sysctl-share-unsigned-long-const-values +++ a/fs/proc/proc_sysctl.c @@ -29,6 +29,9 @@ static const struct inode_operations pro const int sysctl_vals[] = { -1, 0, 1, 2, 4, 100, 200, 1000, 3000, 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[] = { --- a/include/linux/sysctl.h~sysctl-share-unsigned-long-const-values +++ a/include/linux/sysctl.h @@ -51,6 +51,12 @@ 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); --- a/kernel/sysctl.c~sysctl-share-unsigned-long-const-values +++ a/kernel/sysctl.c @@ -100,9 +100,6 @@ /* 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 @@ -2513,7 +2510,7 @@ 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", @@ -2931,8 +2928,8 @@ 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", _
