sched/fair: Remove 'cpu_busy' parameter from update_next_balance()

The update_next_balance() function is only used by idle balancing, so its
'cpu_busy' parameter is always 0.

Open code it instead of passing it around.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1470378689-14892-1-git-send-email-leo.yan@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -7704,11 +7704,12 @@ get_sd_balance_interval(struct sched_domain *sd, int cpu_busy)
 }
 
 static inline void
-update_next_balance(struct sched_domain *sd, int cpu_busy, unsigned long *next_balance)
+update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
 {
 	unsigned long interval, next;
 
-	interval = get_sd_balance_interval(sd, cpu_busy);
+	/* used by idle balance, so cpu_busy = 0 */
+	interval = get_sd_balance_interval(sd, 0);
 	next = sd->last_balance + interval;
 
 	if (time_after(*next_balance, next))
@@ -7738,7 +7739,7 @@ static int idle_balance(struct rq *this_rq)
 		rcu_read_lock();
 		sd = rcu_dereference_check_sched_domain(this_rq->sd);
 		if (sd)
-			update_next_balance(sd, 0, &next_balance);
+			update_next_balance(sd, &next_balance);
 		rcu_read_unlock();
 
 		goto out;
@@ -7756,7 +7757,7 @@ static int idle_balance(struct rq *this_rq)
 			continue;
 
 		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
-			update_next_balance(sd, 0, &next_balance);
+			update_next_balance(sd, &next_balance);
 			break;
 		}
 
@@ -7774,7 +7775,7 @@ static int idle_balance(struct rq *this_rq)
 			curr_cost += domain_cost;
 		}
 
-		update_next_balance(sd, 0, &next_balance);
+		update_next_balance(sd, &next_balance);
 
 		/*
 		 * Stop searching for tasks to pull if there are