From ac1f591249d95372f3a5ab3828d4af5dfbf5efd3 Mon Sep 17 00:00:00 2001
From: Don Zickus <dzickus@redhat.com>
Date: Thu, 5 Nov 2015 18:44:44 -0800
Subject: [PATCH] kernel/watchdog.c: add sysctl knob hardlockup_panic
The only way to enable a hardlockup to panic the machine is to set
'nmi_watchdog=panic' on the kernel command line.
This makes it awkward for end users and folks who want to run automate
tests (like myself).
Mimic the softlockup_panic knob and create a /proc/sys/kernel/hardlockup_panic
knob.
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Documentation/lockup-watchdogs.txt | 5 +++--
include/linux/sched.h | 1 +
kernel/sysctl.c | 11 +++++++++++
kernel/watchdog.c | 2 +-
4 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/Documentation/lockup-watchdogs.txt b/Documentation/lockup-watchdogs.txt
index 22dd6af2e4bd42..4a6e33e1af61e8 100644
--- a/Documentation/lockup-watchdogs.txt
+++ b/Documentation/lockup-watchdogs.txt
@@ -20,8 +20,9 @@ kernel mode for more than 10 seconds (see "Implementation" below for
details), without letting other interrupts have a chance to run.
Similarly to the softlockup case, the current stack trace is displayed
upon detection and the system will stay locked up unless the default
-behavior is changed, which can be done through a compile time knob,
-"BOOTPARAM_HARDLOCKUP_PANIC", and a kernel parameter, "nmi_watchdog"
+behavior is changed, which can be done through a sysctl,
+'hardlockup_panic', a compile time knob, "BOOTPARAM_HARDLOCKUP_PANIC",
+and a kernel parameter, "nmi_watchdog"
(see "Documentation/kernel-parameters.txt" for details).
The panic option can be used in combination with panic_timeout (this
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c115d617739d8e..5423b9c82fee09 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -384,6 +384,7 @@ extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
void __user *buffer,
size_t *lenp, loff_t *ppos);
extern unsigned int softlockup_panic;
+extern unsigned int hardlockup_panic;
void lockup_detector_init(void);
#else
static inline void touch_softlockup_watchdog(void)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 1a5faa3e15218d..dc6858d6639ed0 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -888,6 +888,17 @@ static struct ctl_table kern_table[] = {
.extra1 = &zero,
.extra2 = &one,
},
+#ifdef CONFIG_HARDLOCKUP_DETECTOR
+ {
+ .procname = "hardlockup_panic",
+ .data = &hardlockup_panic,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+#endif
#ifdef CONFIG_SMP
{
.procname = "softlockup_all_cpu_backtrace",
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index f6b32b8cbffe29..0a23125369f14d 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -112,7 +112,7 @@ static unsigned long soft_lockup_nmi_warn;
* Should we panic when a soft-lockup or hard-lockup occurs:
*/
#ifdef CONFIG_HARDLOCKUP_DETECTOR
-static int hardlockup_panic =
+unsigned int __read_mostly hardlockup_panic =
CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
static unsigned long hardlockup_allcpu_dumped;
/*
--
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