rcu: fixes to include/linux/rcupreempt.h

Hello!

Compared tip/core/rcu to my latest patchset, and found the following
issues:

o	the memory barrier in rcu_exit_nohz() somehow got out of place
	(it is correct in mainline as of 2.6.26-rc7).

o	There is a duplicate declaration of rcu_dyntick_sched.

The attached patch fixes these.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/linux/rcupreempt.h

@@ -111,7 +111,6 @@ extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
 struct softirq_action;
 
 #ifdef CONFIG_NO_HZ
-DECLARE_PER_CPU(struct rcu_dyntick_sched, rcu_dyntick_sched);
 
 static inline void rcu_enter_nohz(void)
 {
@@ -126,8 +125,8 @@ static inline void rcu_exit_nohz(void)
 {
 	static DEFINE_RATELIMIT_STATE(rs, 10 * HZ, 1);
 
-	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
 	__get_cpu_var(rcu_dyntick_sched).dynticks++;
+	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
 	WARN_ON_RATELIMIT(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1),
 				&rs);
 }