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authorMandeep Singh Baines <msb@google.com>2009-01-13 00:15:17 -0500
committerIngo Molnar <mingo@elte.hu>2009-01-14 05:48:07 -0500
commitbaf48f6577e581a9adb8fe849dc80e24b21d171d (patch)
tree279e54b7374a9c52025ded4f9bb718e5382b0340
parente4fa4c97016037620f9dc8bafe03e1086b665b4c (diff)
softlock: fix false panic which can occur if softlockup_thresh is reduced
At run-time, if softlockup_thresh is changed to a much lower value, touch_timestamp is likely to be much older than the new softlock_thresh. This will cause a false softlockup to be detected. If softlockup_panic is enabled, the system will panic. The fix is to touch all watchdogs before changing softlockup_thresh. Signed-off-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/sched.h3
-rw-r--r--kernel/softlockup.c9
-rw-r--r--kernel/sysctl.c2
3 files changed, 13 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4cae9b81a1f8..54cbabf3b871 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -293,6 +293,9 @@ extern void sched_show_task(struct task_struct *p);
293extern void softlockup_tick(void); 293extern void softlockup_tick(void);
294extern void touch_softlockup_watchdog(void); 294extern void touch_softlockup_watchdog(void);
295extern void touch_all_softlockup_watchdogs(void); 295extern void touch_all_softlockup_watchdogs(void);
296extern int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
297 struct file *filp, void __user *buffer,
298 size_t *lenp, loff_t *ppos);
296extern unsigned int softlockup_panic; 299extern unsigned int softlockup_panic;
297extern unsigned long sysctl_hung_task_check_count; 300extern unsigned long sysctl_hung_task_check_count;
298extern unsigned long sysctl_hung_task_timeout_secs; 301extern unsigned long sysctl_hung_task_timeout_secs;
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index d9188c66278a..85d5a2455103 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -16,6 +16,7 @@
16#include <linux/lockdep.h> 16#include <linux/lockdep.h>
17#include <linux/notifier.h> 17#include <linux/notifier.h>
18#include <linux/module.h> 18#include <linux/module.h>
19#include <linux/sysctl.h>
19 20
20#include <asm/irq_regs.h> 21#include <asm/irq_regs.h>
21 22
@@ -88,6 +89,14 @@ void touch_all_softlockup_watchdogs(void)
88} 89}
89EXPORT_SYMBOL(touch_all_softlockup_watchdogs); 90EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
90 91
92int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
93 struct file *filp, void __user *buffer,
94 size_t *lenp, loff_t *ppos)
95{
96 touch_all_softlockup_watchdogs();
97 return proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
98}
99
91/* 100/*
92 * This callback runs from the timer interrupt, and checks 101 * This callback runs from the timer interrupt, and checks
93 * whether the watchdog thread has hung or not: 102 * whether the watchdog thread has hung or not:
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 89d74436318c..596dc31a7116 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -800,7 +800,7 @@ static struct ctl_table kern_table[] = {
800 .data = &softlockup_thresh, 800 .data = &softlockup_thresh,
801 .maxlen = sizeof(int), 801 .maxlen = sizeof(int),
802 .mode = 0644, 802 .mode = 0644,
803 .proc_handler = &proc_dointvec_minmax, 803 .proc_handler = &proc_dosoftlockup_thresh,
804 .strategy = &sysctl_intvec, 804 .strategy = &sysctl_intvec,
805 .extra1 = &neg_one, 805 .extra1 = &neg_one,
806 .extra2 = &sixty, 806 .extra2 = &sixty,