linux-kernel - [PATCH 1/2] watchdog: Remove touch_all_softlockup

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Date:	Thu, 24 Nov 2011 14:53:15 +1100
From:	Anton Blanchard <anton@...ba.org>
To:	Don Zickus <dzickus@...hat.com>,
	Jeremy Fitzhardinge <jeremy@...source.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] watchdog: Remove touch_all_softlockup_watchdogs


commit 04c9167f91e3 (add touch_all_softlockup_watchdogs()) added a
way to touch the watchdog on all cpus because show_state_filter
could hold the tasklist_lock for extended periods of time.

commit 510f5acc4f4f (sched: Don't use tasklist_lock for debug prints)
has since removed the tasklist_lock in show_state_filter so we can
use touch_softlockup_watchdog instead.

Signed-off-by: Anton Blanchard <anton@...ba.org>
---

Index: linux-build/include/linux/sched.h
===================================================================
--- linux-build.orig/include/linux/sched.h	2011-11-16 07:57:25.054353865 +1100
+++ linux-build/include/linux/sched.h	2011-11-16 08:04:56.270478443 +1100
@@ -310,7 +310,6 @@ extern void sched_show_task(struct task_
 #ifdef CONFIG_LOCKUP_DETECTOR
 extern void touch_softlockup_watchdog(void);
 extern void touch_softlockup_watchdog_sync(void);
-extern void touch_all_softlockup_watchdogs(void);
 extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
 				  void __user *buffer,
 				  size_t *lenp, loff_t *ppos);
@@ -323,9 +322,6 @@ static inline void touch_softlockup_watc
 static inline void touch_softlockup_watchdog_sync(void)
 {
 }
-static inline void touch_all_softlockup_watchdogs(void)
-{
-}
 static inline void lockup_detector_init(void)
 {
 }
Index: linux-build/kernel/sched.c
===================================================================
--- linux-build.orig/kernel/sched.c	2011-11-16 07:57:25.066354081 +1100
+++ linux-build/kernel/sched.c	2011-11-16 08:04:56.274478516 +1100
@@ -6033,7 +6033,7 @@ void show_state_filter(unsigned long sta
 			sched_show_task(p);
 	} while_each_thread(g, p);
 
-	touch_all_softlockup_watchdogs();
+	touch_softlockup_watchdog();
 
 #ifdef CONFIG_SCHED_DEBUG
 	sysrq_sched_debug_show();
Index: linux-build/kernel/watchdog.c
===================================================================
--- linux-build.orig/kernel/watchdog.c	2011-11-16 07:57:25.626364139 +1100
+++ linux-build/kernel/watchdog.c	2011-11-16 08:04:56.274478516 +1100
@@ -138,19 +138,6 @@ void touch_softlockup_watchdog(void)
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
-void touch_all_softlockup_watchdogs(void)
-{
-	int cpu;
-
-	/*
-	 * this is done lockless
-	 * do we care if a 0 races with a timestamp?
-	 * all it means is the softlock check starts one cycle later
-	 */
-	for_each_online_cpu(cpu)
-		per_cpu(watchdog_touch_ts, cpu) = 0;
-}
-
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 void touch_nmi_watchdog(void)
 {
--
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