rcu: Move redundant call to note_gp_changes() into called function

The __rcu_process_callbacks() invokes note_gp_changes() immediately
before invoking rcu_check_quiescent_state(), which conditionally
invokes that same function.  This commit therefore eliminates the
call to note_gp_changes() in __rcu_process_callbacks() in favor of
making unconditional to call from rcu_check_quiescent_state() to
note_gp_changes().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

kernel/rcutree.c

@@ -1716,11 +1716,8 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
 static void
 rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
 {
-	/* If there is now a new grace period, record and return. */
-	if (rdp->gpnum != rsp->gpnum) {
+	/* Check for grace-period ends and beginnings. */
 	note_gp_changes(rsp, rdp);
-		return;
-	}
 
 	/*
 	 * Does this CPU still need to do its part for current grace period?
@@ -2184,9 +2181,6 @@ __rcu_process_callbacks(struct rcu_state *rsp)
 
 	WARN_ON_ONCE(rdp->beenonline == 0);
 
-	/* Handle the end of a grace period that some other CPU ended.  */
-	note_gp_changes(rsp, rdp);
-
 	/* Update RCU state based on any recent quiescent states. */
 	rcu_check_quiescent_state(rsp, rdp);