rcu: Clean up straggling rcu_preempt_needs_cpu() name

The recent updates to RCU_CPU_FAST_NO_HZ have an rcu_needs_cpu() that
does more than just check for callbacks, so get the name for
rcu_preempt_needs_cpu() consistent with that change, now calling it
rcu_preempt_cpu_has_callbacks().

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcutree.c

@@ -1958,7 +1958,7 @@ static int rcu_cpu_has_callbacks(int cpu)
 	/* RCU callbacks either ready or pending? */
 	return per_cpu(rcu_sched_data, cpu).nxtlist ||
 	       per_cpu(rcu_bh_data, cpu).nxtlist ||
-	       rcu_preempt_needs_cpu(cpu);
+	       rcu_preempt_cpu_has_callbacks(cpu);
 }
 
 static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL};

kernel/rcutree.h

@@ -449,7 +449,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
 			       bool wake);
 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
 static int rcu_preempt_pending(int cpu);
-static int rcu_preempt_needs_cpu(int cpu);
+static int rcu_preempt_cpu_has_callbacks(int cpu);
 static void __cpuinit rcu_preempt_init_percpu_data(int cpu);
 static void rcu_preempt_cleanup_dying_cpu(void);
 static void __init __rcu_init_preempt(void);

kernel/rcutree_plugin.h

@@ -887,9 +887,9 @@ static int rcu_preempt_pending(int cpu)
 }
 
 /*
- * Does preemptible RCU need the CPU to stay out of dynticks mode?
+ * Does preemptible RCU have callbacks on this CPU?
  */
-static int rcu_preempt_needs_cpu(int cpu)
+static int rcu_preempt_cpu_has_callbacks(int cpu)
 {
 	return !!per_cpu(rcu_preempt_data, cpu).nxtlist;
 }
@@ -1128,9 +1128,9 @@ static int rcu_preempt_pending(int cpu)
 }
 
 /*
- * Because preemptible RCU does not exist, it never needs any CPU.
+ * Because preemptible RCU does not exist, it never has callbacks
  */
-static int rcu_preempt_needs_cpu(int cpu)
+static int rcu_preempt_cpu_has_callbacks(int cpu)
 {
 	return 0;
 }