[PATCH] tick: add check for the existence of broadcast clock event device

[Feng Tang <feng.tang@intel.com>]

>From 2f076e1867c8bbb145b74d289358174644d9fed8 Mon Sep 17 00:00:00 2001
From: Feng Tang <feng.tang@intel.com>
Date: Fri, 5 Jun 2009 10:36:15 +0800
Subject: [PATCH] tick: add check for the existence of broadcast clock event device

Some platform may have no broadcast clock event device, as it use always-on
external timers for per-cpu timer and has no extra one for broadcast device.
This check will secure the access to bc device when system get some boradcast
on/off and enter/exit message

Signed-off-by: Feng Tang <feng.tang@intel.com>
---
 kernel/time/tick-broadcast.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 118a3b3..110e0bc 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -214,10 +214,13 @@ static void tick_do_broadcast_on_off(void *why)
 
 	spin_lock_irqsave(&tick_broadcast_lock, flags);
 
+	bc = tick_broadcast_device.evtdev;
+	if (!bc)
+		goto out;
+
 	cpu = smp_processor_id();
 	td = &per_cpu(tick_cpu_device, cpu);
 	dev = td->evtdev;
-	bc = tick_broadcast_device.evtdev;
 
 	/*
 	 * Is the device not affected by the powerstate ?
@@ -468,6 +471,9 @@ void tick_broadcast_oneshot_control(unsigned long reason)
 		goto out;
 
 	bc = tick_broadcast_device.evtdev;
+	if (!bc)
+		goto out;
+
 	cpu = smp_processor_id();
 	td = &per_cpu(tick_cpu_device, cpu);
 	dev = td->evtdev;
-- 
1.5.6.3