linux-kernel - Re: [PATCH] NOHZ, check to see if tick device is initialized in IRQ handling path

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Date:	Fri, 3 May 2013 15:02:50 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Prarit Bhargava <prarit@...hat.com>
cc:	LKML <linux-kernel@...r.kernel.org>,
	John Stultz <john.stultz@...aro.org>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	Dave Jones <davej@...emonkey.org.uk>
Subject: Re: [PATCH] NOHZ, check to see if tick device is initialized in IRQ
 handling path

On Fri, 3 May 2013, Prarit Bhargava wrote:
> Down a cpu and then bring it back up.

Ahhhh. So the issue is, that we do not clear the per cpu ts->inidle
and friends when we bring the cpu down.

The patch below should address that.

Thanks,

	tglx

 
Index: linux-2.6/kernel/time/tick-common.c
===================================================================
--- linux-2.6.orig/kernel/time/tick-common.c
+++ linux-2.6/kernel/time/tick-common.c
@@ -387,6 +387,7 @@ static int tick_notify(struct notifier_b
 		tick_shutdown_broadcast_oneshot(dev);
 		tick_shutdown_broadcast(dev);
 		tick_shutdown(dev);
+		tick_shutdown_nohz(dev);
 		break;
 
 	case CLOCK_EVT_NOTIFY_SUSPEND:
Index: linux-2.6/kernel/time/tick-internal.h
===================================================================
--- linux-2.6.orig/kernel/time/tick-internal.h
+++ linux-2.6/kernel/time/tick-internal.h
@@ -144,3 +144,9 @@ static inline int tick_device_is_functio
 #endif
 
 extern void do_timer(unsigned long ticks);
+
+#ifdef CONFIG_NO_HZ
+extern void tick_shutdown_nohz(unsigned int *cpup);
+#else
+static inline void tick_shutdown_nohz(unsigned int *cpup) { }
+#endif
Index: linux-2.6/kernel/time/tick-sched.c
===================================================================
--- linux-2.6.orig/kernel/time/tick-sched.c
+++ linux-2.6/kernel/time/tick-sched.c
@@ -797,6 +797,13 @@ static inline void tick_check_nohz(int c
 	}
 }
 
+void tick_shutdown_nohz(unsigned int *cpup)
+{
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+
+	memset(ts, 0, sizeof(*ts));
+}
+
 #else
 
 static inline void tick_nohz_switch_to_nohz(void) { }
--
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