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>
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index d9188c6..85d5a24 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -16,6 +16,7 @@
#include <linux/lockdep.h>
#include <linux/notifier.h>
#include <linux/module.h>
+#include <linux/sysctl.h>
#include <asm/irq_regs.h>
@@ -88,6 +89,14 @@
}
EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
+int proc_dosoftlockup_thresh(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ touch_all_softlockup_watchdogs();
+ return proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+}
+
/*
* This callback runs from the timer interrupt, and checks
* whether the watchdog thread has hung or not: