sched/core: Create task_has_idle_policy() helper

We already have task_has_rt_policy() and task_has_dl_policy() helpers,
create task_has_idle_policy() as well and update sched core to start
using it.

While at it, use task_has_dl_policy() at one more place.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/ce3915d5b490fc81af926a3b6bfb775e7188e005.1541416894.git.viresh.kumar@linaro.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -697,7 +697,7 @@ static void set_load_weight(struct task_struct *p, bool update_load)
 	/*
 	 * SCHED_IDLE tasks get minimal weight:
 	 */
-	if (idle_policy(p->policy)) {
+	if (task_has_idle_policy(p)) {
 		load->weight = scale_load(WEIGHT_IDLEPRIO);
 		load->inv_weight = WMULT_IDLEPRIO;
 		p->se.runnable_weight = load->weight;
@@ -4199,7 +4199,7 @@ static int __sched_setscheduler(struct task_struct *p,
 		 * Treat SCHED_IDLE as nice 20. Only allow a switch to
 		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
 		 */
-		if (idle_policy(p->policy) && !idle_policy(policy)) {
+		if (task_has_idle_policy(p) && !idle_policy(policy)) {
 			if (!can_nice(p, task_nice(p)))
 				return -EPERM;
 		}

kernel/sched/debug.c

@@ -974,7 +974,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
 #endif
 	P(policy);
 	P(prio);
-	if (p->policy == SCHED_DEADLINE) {
+	if (task_has_dl_policy(p)) {
 		P(dl.runtime);
 		P(dl.deadline);
 	}

kernel/sched/fair.c

@@ -6529,7 +6529,7 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
 
 static void set_last_buddy(struct sched_entity *se)
 {
-	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+	if (entity_is_task(se) && unlikely(task_has_idle_policy(task_of(se))))
 		return;
 
 	for_each_sched_entity(se) {
@@ -6541,7 +6541,7 @@ static void set_last_buddy(struct sched_entity *se)
 
 static void set_next_buddy(struct sched_entity *se)
 {
-	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+	if (entity_is_task(se) && unlikely(task_has_idle_policy(task_of(se))))
 		return;
 
 	for_each_sched_entity(se) {
@@ -6599,8 +6599,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
 		return;
 
 	/* Idle tasks are by definition preempted by non-idle tasks. */
-	if (unlikely(curr->policy == SCHED_IDLE) &&
-	    likely(p->policy != SCHED_IDLE))
+	if (unlikely(task_has_idle_policy(curr)) &&
+	    likely(!task_has_idle_policy(p)))
 		goto preempt;
 
 	/*
@@ -7021,7 +7021,7 @@ static int task_hot(struct task_struct *p, struct lb_env *env)
 	if (p->sched_class != &fair_sched_class)
 		return 0;
 
-	if (unlikely(p->policy == SCHED_IDLE))
+	if (unlikely(task_has_idle_policy(p)))
 		return 0;
 
 	/*

kernel/sched/sched.h

@@ -176,6 +176,11 @@ static inline bool valid_policy(int policy)
 		rt_policy(policy) || dl_policy(policy);
 }
 
+static inline int task_has_idle_policy(struct task_struct *p)
+{
+	return idle_policy(p->policy);
+}
+
 static inline int task_has_rt_policy(struct task_struct *p)
 {
 	return rt_policy(p->policy);