linux-kernel - [PATCH 7/9] lockup_detector: Separate touch_nmi_watchdog code path from touch

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Message-Id: <1273713674-8434-8-git-send-regression-fweisbec@gmail.com>
Date:	Thu, 13 May 2010 03:21:12 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Don Zickus <dzickus@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	Eric Paris <eparis@...hat.com>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH 7/9] lockup_detector: Separate touch_nmi_watchdog code path from touch_watchdog

From: Don Zickus <dzickus@...hat.com>

When I combined the nmi_watchdog (hardlockup) and softlockup code, I
also combined the paths the touch_watchdog and touch_nmi_watchdog took.
This may not be the best idea as pointed out by Frederic W., that the
touch_watchdog case probably should not reset the hardlockup count.

Therefore the patch below falls back to the previous idea of keeping
the touch_nmi_watchdog a superset of the touch_watchdog case.

Signed-off-by: Don Zickus <dzickus@...hat.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Cyrill Gorcunov <gorcunov@...il.com>
Cc: Eric Paris <eparis@...hat.com>
Cc: Randy Dunlap <randy.dunlap@...cle.com>
LKML-Reference: <1273266711-18706-9-git-send-email-dzickus@...hat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 kernel/watchdog.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index f1541b7..57b8e2c 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -31,6 +31,7 @@ int watchdog_enabled;
 int __read_mostly softlockup_thresh = 60;
 
 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
+static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
 static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
 static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
 static DEFINE_PER_CPU(bool, softlockup_touch_sync);
@@ -139,6 +140,7 @@ void touch_all_softlockup_watchdogs(void)
 
 void touch_nmi_watchdog(void)
 {
+	__get_cpu_var(watchdog_nmi_touch) = true;
 	touch_softlockup_watchdog();
 }
 EXPORT_SYMBOL(touch_nmi_watchdog);
@@ -201,10 +203,9 @@ void watchdog_overflow_callback(struct perf_event *event, int nmi,
 		 struct pt_regs *regs)
 {
 	int this_cpu = smp_processor_id();
-	unsigned long touch_ts = per_cpu(watchdog_touch_ts, this_cpu);
 
-	if (touch_ts == 0) {
-		__touch_watchdog();
+	if (__get_cpu_var(watchdog_nmi_touch) == true) {
+		__get_cpu_var(watchdog_nmi_touch) = false;
 		return;
 	}
 
-- 
1.6.2.3

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