From: Xiaoming Ni <nixiaoming@xxxxxxxxxx> Subject: sysctl: use const for typically used max/min proc sysctls When proc_dointvec_minmax() or proc_doulongvec_minmax() are used we are using the extra1 and extra2 parameters on the sysctl table only for a min and max boundary, these extra1 and extra2 arguments are then used for read-only operations. So make them const to reflect this. [mcgrof@xxxxxxxxxx: commit log love] Link: https://lkml.kernel.org/r/20211123202347.818157-7-mcgrof@xxxxxxxxxx Signed-off-by: Xiaoming Ni <nixiaoming@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: Benjamin LaHaise <bcrl@xxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Iurii Zaikin <yzaikin@xxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Paul Turner <pjt@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Qing Wang <wangqing@xxxxxxxx> Cc: Sebastian Reichel <sre@xxxxxxxxxx> Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> Cc: Stephen Kitt <steve@xxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Cc: Antti Palosaari <crope@xxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Clemens Ladisch <clemens@xxxxxxxxxx> Cc: David Airlie <airlied@xxxxxxxx> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> Cc: Joel Becker <jlbec@xxxxxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> Cc: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> Cc: Julia Lawall <julia.lawall@xxxxxxxx> Cc: Lukas Middendorf <kernel@xxxxxxxxxxx> Cc: Mark Fasheh <mark@xxxxxxxxxx> Cc: Phillip Potter <phil@xxxxxxxxxxxxxxxx> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> Cc: Douglas Gilbert <dgilbert@xxxxxxxxxxxx> Cc: James E.J. Bottomley <jejb@xxxxxxxxxxxxx> Cc: Jani Nikula <jani.nikula@xxxxxxxxx> Cc: John Ogness <john.ogness@xxxxxxxxxxxxx> Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> Cc: "Theodore Ts'o" <tytso@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/sysctl.c | 53 ++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 27 deletions(-) --- a/kernel/sysctl.c~sysctl-use-const-for-typically-used-max-min-proc-sysctls +++ a/kernel/sysctl.c @@ -108,27 +108,26 @@ /* Constants used for minimum and maximum */ -static unsigned long zero_ul; -static unsigned long one_ul = 1; -static unsigned long long_max = LONG_MAX; +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 int ten_thousand = 10000; +static const int ten_thousand = 10000; #endif #ifdef CONFIG_PERF_EVENTS -static int six_hundred_forty_kb = 640 * 1024; +static const int six_hundred_forty_kb = 640 * 1024; #endif /* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */ -static unsigned long dirty_bytes_min = 2 * PAGE_SIZE; +static const unsigned long dirty_bytes_min = 2 * PAGE_SIZE; /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */ -static int maxolduid = 65535; -static int minolduid; +static const int maxolduid = 65535; +static const int minolduid; static const int ngroups_max = NGROUPS_MAX; static const int cap_last_cap = CAP_LAST_CAP; - #ifdef CONFIG_INOTIFY_USER #include <linux/inotify.h> #endif @@ -172,8 +171,8 @@ int sysctl_legacy_va_layout; #endif #ifdef CONFIG_COMPACTION -static int min_extfrag_threshold; -static int max_extfrag_threshold = 1000; +static const int min_extfrag_threshold; +static const int max_extfrag_threshold = 1000; #endif #endif /* CONFIG_SYSCTL */ @@ -2177,8 +2176,8 @@ static struct ctl_table kern_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &minolduid, - .extra2 = &maxolduid, + .extra1 = (void *)&minolduid, + .extra2 = (void *)&maxolduid, }, { .procname = "overflowgid", @@ -2186,8 +2185,8 @@ static struct ctl_table kern_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &minolduid, - .extra2 = &maxolduid, + .extra1 = (void *)&minolduid, + .extra2 = (void *)&maxolduid, }, #ifdef CONFIG_S390 { @@ -2261,7 +2260,7 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_dointvec_minmax, .extra1 = SYSCTL_ZERO, - .extra2 = &ten_thousand, + .extra2 = (void *)&ten_thousand, }, { .procname = "printk_devkmsg", @@ -2473,7 +2472,7 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = perf_event_max_stack_handler, .extra1 = SYSCTL_ZERO, - .extra2 = &six_hundred_forty_kb, + .extra2 = (void *)&six_hundred_forty_kb, }, { .procname = "perf_event_max_contexts_per_stack", @@ -2629,7 +2628,7 @@ static struct ctl_table vm_table[] = { .maxlen = sizeof(dirty_background_bytes), .mode = 0644, .proc_handler = dirty_background_bytes_handler, - .extra1 = &one_ul, + .extra1 = (void *)&one_ul, }, { .procname = "dirty_ratio", @@ -2646,7 +2645,7 @@ static struct ctl_table vm_table[] = { .maxlen = sizeof(vm_dirty_bytes), .mode = 0644, .proc_handler = dirty_bytes_handler, - .extra1 = &dirty_bytes_min, + .extra1 = (void *)&dirty_bytes_min, }, { .procname = "dirty_writeback_centisecs", @@ -2760,8 +2759,8 @@ static struct ctl_table vm_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &min_extfrag_threshold, - .extra2 = &max_extfrag_threshold, + .extra1 = (void *)&min_extfrag_threshold, + .extra2 = (void *)&max_extfrag_threshold, }, { .procname = "compact_unevictable_allowed", @@ -3047,8 +3046,8 @@ static struct ctl_table fs_table[] = { .maxlen = sizeof(files_stat.max_files), .mode = 0644, .proc_handler = proc_doulongvec_minmax, - .extra1 = &zero_ul, - .extra2 = &long_max, + .extra1 = (void *)&zero_ul, + .extra2 = (void *)&long_max, }, { .procname = "nr_open", @@ -3072,8 +3071,8 @@ static struct ctl_table fs_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &minolduid, - .extra2 = &maxolduid, + .extra1 = (void *)&minolduid, + .extra2 = (void *)&maxolduid, }, { .procname = "overflowgid", @@ -3081,8 +3080,8 @@ static struct ctl_table fs_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &minolduid, - .extra2 = &maxolduid, + .extra1 = (void *)&minolduid, + .extra2 = (void *)&maxolduid, }, #ifdef CONFIG_FILE_LOCKING { _
