kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases

After a recent change introduced by Vlastimil's series [0], kernel is
able now to handle sysctl parameters on kernel command line; also, the
series introduced a simple infrastructure to convert legacy boot
parameters (that duplicate sysctls) into sysctl aliases.

This patch converts the watchdog parameters softlockup_panic and
{hard,soft}lockup_all_cpu_backtrace to use the new alias infrastructure.
It fixes the documentation too, since the alias only accepts values 0 or
1, not the full range of integers.

We also took the opportunity here to improve the documentation of the
previously converted hung_task_panic (see the patch series [0]) and put
the alias table in alphabetical order.

[0] http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz

Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Link: http://lkml.kernel.org/r/20200507214624.21911-1-gpiccoli@canonical.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 28 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 53ff2c81b084..5abb5b22ad13 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -50,6 +50,11 @@ struct cpumask watchdog_cpumask __read_mostly;
 unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
+
+# ifdef CONFIG_SMP
+int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
+# endif /* CONFIG_SMP */
+
 /*
  * Should we panic when a soft-lockup or hard-lockup occurs:
  */
@@ -82,16 +87,6 @@ static int __init hardlockup_panic_setup(char *str)
 }
 __setup("nmi_watchdog=", hardlockup_panic_setup);
 
-# ifdef CONFIG_SMP
-int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
-
-static int __init hardlockup_all_cpu_backtrace_setup(char *str)
-{
-	sysctl_hardlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0);
-	return 1;
-}
-__setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup);
-# endif /* CONFIG_SMP */
 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
 
 /*
@@ -163,6 +158,10 @@ static void lockup_detector_update_enable(void)
 
 #define SOFTLOCKUP_RESET	ULONG_MAX
 
+#ifdef CONFIG_SMP
+int __read_mostly sysctl_softlockup_all_cpu_backtrace;
+#endif
+
 /* Global variables, exported for sysctl */
 unsigned int __read_mostly softlockup_panic =
 			CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
@@ -178,13 +177,6 @@ static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
 static unsigned long soft_lockup_nmi_warn;
 
-static int __init softlockup_panic_setup(char *str)
-{
-	softlockup_panic = simple_strtoul(str, NULL, 0);
-	return 1;
-}
-__setup("softlockup_panic=", softlockup_panic_setup);
-
 static int __init nowatchdog_setup(char *str)
 {
 	watchdog_user_enabled = 0;
@@ -206,17 +198,6 @@ static int __init watchdog_thresh_setup(char *str)
 }
 __setup("watchdog_thresh=", watchdog_thresh_setup);
 
-#ifdef CONFIG_SMP
-int __read_mostly sysctl_softlockup_all_cpu_backtrace;
-
-static int __init softlockup_all_cpu_backtrace_setup(char *str)
-{
-	sysctl_softlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0);
-	return 1;
-}
-__setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup);
-#endif
-
 static void __lockup_detector_cleanup(void);
 
 /*