rcu: Remove "cpu" argument to rcu_cleanup_after_idle()

The "cpu" argument to rcu_cleanup_after_idle() is always the current
CPU, so drop it.  This moves the smp_processor_id() from the caller to
rcu_cleanup_after_idle(), saving argument-passing overhead.  Again,
the anticipated cross-CPU uses of these functions has been replaced
by NO_HZ_FULL.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>

kernel/rcu/tree.c

@@ -661,7 +661,7 @@ static void rcu_eqs_exit_common(long long oldval, int user)
 	/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
 	smp_mb__after_atomic();  /* See above. */
 	WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
-	rcu_cleanup_after_idle(smp_processor_id());
+	rcu_cleanup_after_idle();
 	trace_rcu_dyntick(TPS("End"), oldval, rdtp->dynticks_nesting);
 	if (!user && !is_idle_task(current)) {
 		struct task_struct *idle __maybe_unused =

kernel/rcu/tree.h

@@ -579,7 +579,7 @@ static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
 #endif /* #ifdef CONFIG_RCU_BOOST */
 static void __init rcu_spawn_boost_kthreads(void);
 static void rcu_prepare_kthreads(int cpu);
-static void rcu_cleanup_after_idle(int cpu);
+static void rcu_cleanup_after_idle(void);
 static void rcu_prepare_for_idle(void);
 static void rcu_idle_count_callbacks_posted(void);
 static void print_cpu_stall_info_begin(void);

kernel/rcu/tree_plugin.h

@@ -1523,7 +1523,7 @@ int rcu_needs_cpu(unsigned long *delta_jiffies)
  * Because we do not have RCU_FAST_NO_HZ, don't bother cleaning up
  * after it.
  */
-static void rcu_cleanup_after_idle(int cpu)
+static void rcu_cleanup_after_idle(void)
 {
 }
 
@@ -1731,10 +1731,10 @@ static void rcu_prepare_for_idle(void)
  * any grace periods that elapsed while the CPU was idle, and if any
  * callbacks are now ready to invoke, initiate invocation.
  */
-static void rcu_cleanup_after_idle(int cpu)
+static void rcu_cleanup_after_idle(void)
 {
 #ifndef CONFIG_RCU_NOCB_CPU_ALL
-	if (rcu_is_nocb_cpu(cpu))
+	if (rcu_is_nocb_cpu(smp_processor_id()))
 		return;
 	if (rcu_try_advance_all_cbs())
 		invoke_rcu_core();