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Message-Id: <1386107674-15903-1-git-send-email-benzh@chromium.org>
Date: Tue, 3 Dec 2013 13:54:34 -0800
From: Ben Zhang <benzh@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: Don Zickus <dzickus@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Ingo Molnar <mingo@...hat.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Ben Zhang <benzh@...omium.org>
Subject: [PATCH] watchdog: Add a sysctl to disable soft lockup detector
This provides usermode a way to disable only the soft
lockup detector while keeping the hard lockup detector
running.
kernel.softlockup_detector_enable=1:
This is the default. The soft lockup detector is enabled.
When a soft lockup is detected, a warning message with
debug info is printed. The kernel may be configured to
panics in this case via the sysctl kernel.softlockup_panic.
kernel.softlockup_detector_enable=0:
The soft lockup detector is disabled. Warning message is
not printed on soft lockup. The kernel does not panic on
soft lockup regardless of the value of kernel.softlockup_panic.
Note kernel.softlockup_detector_enable does not affect
the hard lockup detector.
Signed-off-by: Ben Zhang <benzh@...omium.org>
---
include/linux/sched.h | 1 +
kernel/sysctl.c | 9 +++++++++
kernel/watchdog.c | 15 +++++++++++++++
3 files changed, 25 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 768b037..93ebec4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -270,6 +270,7 @@ 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 softlockup_detector_enable;
void lockup_detector_init(void);
#else
static inline void touch_softlockup_watchdog(void)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 34a6047..8ae1f36 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -840,6 +840,15 @@ static struct ctl_table kern_table[] = {
.extra2 = &one,
},
{
+ .procname = "softlockup_detector_enable",
+ .data = &softlockup_detector_enable,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+ {
.procname = "nmi_watchdog",
.data = &watchdog_user_enabled,
.maxlen = sizeof (int),
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 4431610..b9594e6 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -80,6 +80,18 @@ static int __init softlockup_panic_setup(char *str)
}
__setup("softlockup_panic=", softlockup_panic_setup);
+unsigned int __read_mostly softlockup_detector_enable = 1;
+
+static int __init softlockup_detector_enable_setup(char *str)
+{
+ unsigned long res;
+ if (kstrtoul(str, 0, &res))
+ res = 1;
+ softlockup_detector_enable = res;
+ return 1;
+}
+__setup("softlockup_detector_enable=", softlockup_detector_enable_setup);
+
static int __init nowatchdog_setup(char *str)
{
watchdog_user_enabled = 0;
@@ -293,6 +305,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
return HRTIMER_RESTART;
}
+ if (!softlockup_detector_enable)
+ return HRTIMER_RESTART;
+
/* check for a softlockup
* This is done by making sure a high priority task is
* being scheduled. The task touches the watchdog to
--
1.8.4.1
--
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