The patch titled
Subject: watchdog/softlockup: enforce that timestamp is valid on boot
has been added to the -mm tree. Its filename is
watchdog-softlockup-enforce-that-timestamp-is-valid-on-boot.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/watchdog-softlockup-enforce-that-timestamp-is-valid-on-boot.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/watchdog-softlockup-enforce-that-timestamp-is-valid-on-boot.patch
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------------------------------------------------------
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Subject: watchdog/softlockup: enforce that timestamp is valid on boot
Robert reported that during boot the watchdog timestamp is set to 0 for
one second which is the indicator for a watchdog reset.
The reason for this is that the timestamp is in seconds and the time is
taken from sched clock and divided by ~1e9. sched clock starts at 0 which
means that for the first second during boot the watchdog timestamp is 0,
i.e. reset.
Use ULONG_MAX as the reset indicator value so the watchdog works correctly
right from the start. ULONG_MAX would only conflict with a real timestamp
if the system reaches an uptime of 136 years on 32bit and almost eternity
on 64bit.
Link: http://lkml.kernel.org/r/87o8v3uuzl.fsf@xxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reported-by: Robert Richter <rrichter@xxxxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/watchdog.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/kernel/watchdog.c~watchdog-softlockup-enforce-that-timestamp-is-valid-on-boot
+++ a/kernel/watchdog.c
@@ -161,6 +161,8 @@ static void lockup_detector_update_enabl
#ifdef CONFIG_SOFTLOCKUP_DETECTOR
+#define SOFTLOCKUP_RESET ULONG_MAX
+
/* Global variables, exported for sysctl */
unsigned int __read_mostly softlockup_panic =
CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
@@ -274,7 +276,7 @@ notrace void touch_softlockup_watchdog_s
* Preemption can be enabled. It doesn't matter which CPU's timestamp
* gets zeroed here, so use the raw_ operation.
*/
- raw_cpu_write(watchdog_touch_ts, 0);
+ raw_cpu_write(watchdog_touch_ts, SOFTLOCKUP_RESET);
}
notrace void touch_softlockup_watchdog(void)
@@ -298,14 +300,14 @@ void touch_all_softlockup_watchdogs(void
* the softlockup check.
*/
for_each_cpu(cpu, &watchdog_allowed_mask)
- per_cpu(watchdog_touch_ts, cpu) = 0;
+ per_cpu(watchdog_touch_ts, cpu) = SOFTLOCKUP_RESET;
wq_watchdog_touch(-1);
}
void touch_softlockup_watchdog_sync(void)
{
__this_cpu_write(softlockup_touch_sync, true);
- __this_cpu_write(watchdog_touch_ts, 0);
+ __this_cpu_write(watchdog_touch_ts, SOFTLOCKUP_RESET);
}
static int is_softlockup(unsigned long touch_ts)
@@ -383,7 +385,7 @@ static enum hrtimer_restart watchdog_tim
/* .. and repeat */
hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
- if (touch_ts == 0) {
+ if (touch_ts == SOFTLOCKUP_RESET) {
if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
/*
* If the time stamp was touched atomically
_
Patches currently in -mm which might be from tglx@xxxxxxxxxxxxx are
watchdog-softlockup-enforce-that-timestamp-is-valid-on-boot.patch
