The patch titled
Subject: watchdog: use bit lock operations to prevent multiple soft-lockup reports
has been removed from the -mm tree. Its filename was
watchdog-fix-barriers-when-printing-backtraces-from-all-cpus-fix.patch
This patch was dropped because it was folded into watchdog-fix-barriers-when-printing-backtraces-from-all-cpus.patch
------------------------------------------------------
From: Petr Mladek <pmladek@xxxxxxxx>
Subject: watchdog: use bit lock operations to prevent multiple soft-lockup reports
Use bit_lock operation to prevent multiple soft-lockups reports when one
CPU already triggered dumping backtraces from all CPUs.
It allows to remove the explicit memory barriers and misleading
comments.
Link: https://lkml.kernel.org/r/YFSVsLGVWMXTvlbk@alley
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/watchdog.c | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)
--- a/kernel/watchdog.c~watchdog-fix-barriers-when-printing-backtraces-from-all-cpus-fix
+++ a/kernel/watchdog.c
@@ -415,13 +415,8 @@ static enum hrtimer_restart watchdog_tim
* engaged in dumping all cpu back traces.
*/
if (softlockup_all_cpu_backtrace) {
- if (test_and_set_bit(0, &soft_lockup_nmi_warn))
+ if (test_and_set_bit_lock(0, &soft_lockup_nmi_warn))
return HRTIMER_RESTART;
- /*
- * Make sure that reports are serialized. Start
- * printing after getting the exclusive rights.
- */
- smp_mb__after_atomic();
}
/* Start period for the next softlockup warning. */
@@ -439,13 +434,7 @@ static enum hrtimer_restart watchdog_tim
if (softlockup_all_cpu_backtrace) {
trigger_allbutself_cpu_backtrace();
- /*
- * Make sure that everything is printed before
- * another CPU is allowed to report lockup again.
- */
- smp_mb__before_atomic();
- /* Allow a further report. */
- clear_bit(0, &soft_lockup_nmi_warn);
+ clear_bit_unlock(0, &soft_lockup_nmi_warn);
}
add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
_
Patches currently in -mm which might be from pmladek@xxxxxxxx are
watchdog-rename-__touch_watchdog-to-a-better-descriptive-name.patch
watchdog-explicitly-update-timestamp-when-reporting-softlockup.patch
watchdog-softlockup-report-the-overall-time-of-softlockups.patch
watchdog-softlockup-remove-logic-that-tried-to-prevent-repeated-reports.patch
watchdog-fix-barriers-when-printing-backtraces-from-all-cpus.patch
watchdog-cleanup-handling-of-false-positives.patch
