[rt] fix locking when taking down a CPU

svn path=/dists/sid/linux-2.6/; revision=18798

debian/changelog

@@ -1,3 +1,9 @@
+linux-2.6 (3.2.9-2) UNRELEASED; urgency=low
+
+  * [rt] fix locking when taking down a CPU
+
+ -- Uwe Kleine-König <u.kleine-koenig@pengutronix.de>  Tue, 06 Mar 2012 09:26:00 +0100
+
 linux-2.6 (3.2.9-1) unstable; urgency=high
 
   * New upstream stable update:

debian/patches/features/all/rt/cpu-rt-make-hotplug-lock-a-sleeping-spinlock-on-rt.patch

@@ -18,8 +18,11 @@ Cc: Clark Williams <clark.williams@gmail.com>
 Cc: stable-rt@vger.kernel.org
 Link: http://lkml.kernel.org/r/1330702617.25686.265.camel@gandalf.stny.rr.com
 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+---
+[ukleinek: squash in an obvious fix by Steven Rostedt
+ id:1330985640.25686.342.camel@gandalf.stny.rr.com]
 diff --git a/kernel/cpu.c b/kernel/cpu.c
-index fa40834..c25b5ff 100644
+index fa40834..66dfb74 100644
 --- a/kernel/cpu.c
 +++ b/kernel/cpu.c
 @@ -46,7 +46,12 @@ static int cpu_hotplug_disabled;
@@ -35,16 +38,24 @@ index fa40834..c25b5ff 100644
  	/*
  	 * Also blocks the new readers during
  	 * an ongoing cpu hotplug operation.
-@@ -58,6 +63,14 @@ static struct {
+@@ -54,10 +59,22 @@ static struct {
+ 	int refcount;
+ } cpu_hotplug = {
+ 	.active_writer = NULL,
++#ifdef CONFIG_PREEMPT_RT_FULL
++	.lock = __SPIN_LOCK_UNLOCKED(cpu_hotplug.lock),
++#else
+ 	.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
++#endif
  	.refcount = 0,
  };
  
 +#ifdef CONFIG_PREEMPT_RT_FULL
-+# define hotplug_lock() spin_lock(&cpu_hotplug.lock)
-+# define hotplug_unlock() spin_unlock(&cpu_hotplug.lock)
++# define hotplug_lock() rt_spin_lock(&cpu_hotplug.lock)
++# define hotplug_unlock() rt_spin_unlock(&cpu_hotplug.lock)
 +#else
 +# define hotplug_lock() mutex_lock(&cpu_hotplug.lock)
-+# define hotplug_lock() mutex_unlock(&cpu_hotplug.lock)
++# define hotplug_unlock() mutex_unlock(&cpu_hotplug.lock)
 +#endif
 +
  struct hotplug_pcp {