rcu: ->signaled better named ->fqs_state

The ->signaled field was named before complications in the form of
dyntick-idle mode and offlined CPUs.  These complications have required
that force_quiescent_state() be implemented as a state machine, instead
of simply unconditionally sending reschedule IPIs.  Therefore, this
commit renames ->signaled to ->fqs_state to catch up with the new
force_quiescent_state() reality.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 849ce9e..517f2f8 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -302,7 +302,7 @@
 	struct rcu_state *rsp;
 };
 
-/* Values for signaled field in struct rcu_state. */
+/* Values for fqs_state field in struct rcu_state. */
 #define RCU_GP_IDLE		0	/* No grace period in progress. */
 #define RCU_GP_INIT		1	/* Grace period being initialized. */
 #define RCU_SAVE_DYNTICK	2	/* Need to scan dyntick state. */
@@ -361,7 +361,7 @@
 
 	/* The following fields are guarded by the root rcu_node's lock. */
 
-	u8	signaled ____cacheline_internodealigned_in_smp;
+	u8	fqs_state ____cacheline_internodealigned_in_smp;
 						/* Force QS state. */
 	u8	fqs_active;			/* force_quiescent_state() */
 						/*  is running. */