rcu: Convert to raw_spinlocks

The spinlocks in rcutree need to be real spinlocks in
preempt-rt. Convert them to raw_spinlocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-18-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/rcutree.h

@@ -90,7 +90,7 @@ struct rcu_dynticks {
  * Definition for node within the RCU grace-period-detection hierarchy.
  */
 struct rcu_node {
-	spinlock_t lock;	/* Root rcu_node's lock protects some */
+	raw_spinlock_t lock;	/* Root rcu_node's lock protects some */
 				/*  rcu_state fields as well as following. */
 	unsigned long gpnum;	/* Current grace period for this node. */
 				/*  This will either be equal to or one */
@@ -291,7 +291,7 @@ struct rcu_state {
 
 	/* End of fields guarded by root rcu_node's lock. */
 
-	spinlock_t onofflock;			/* exclude on/offline and */
+	raw_spinlock_t onofflock;		/* exclude on/offline and */
 						/*  starting new GP.  Also */
 						/*  protects the following */
 						/*  orphan_cbs fields. */
@@ -301,7 +301,7 @@ struct rcu_state {
 						/*  going offline. */
 	struct rcu_head **orphan_cbs_tail;	/* And tail pointer. */
 	long orphan_qlen;			/* Number of orphaned cbs. */
-	spinlock_t fqslock;			/* Only one task forcing */
+	raw_spinlock_t fqslock;			/* Only one task forcing */
 						/*  quiescent states. */
 	unsigned long jiffies_force_qs;		/* Time at which to invoke */
 						/*  force_quiescent_state(). */