[folded-merged] watchdog-fix-barriers-when-printing-backtraces-from-all-cpus-fix.patch removed from -mm tree

[akpm@linux-foundation.org]

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@suse.com>
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@suse.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@suse.com 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