[PATCH v2 2/4] sched/fair: Fold cfs_rq_of(se) into for_each_sched_entity()

[Peter Zijlstra <peterz@infradead.org>]

Pretty much every for_each_sched_entity() loop does: cfs_rq = cfs_rq_of(se) as
the very first thing. Fold it into the for_each_sched_entity() macro.

This paves the way to have the macro track a backlink transparantly.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/sched/fair.c |   81 +++++++++++++++++++++++-----------------------------
 1 file changed, 37 insertions(+), 44 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -318,8 +318,8 @@ const struct sched_class fair_sched_clas
 #ifdef CONFIG_FAIR_GROUP_SCHED
 
 /* Walk up scheduling entities hierarchy */
-#define for_each_sched_entity(se) \
-		for (; se; se = se->parent)
+#define for_each_sched_entity(se, cfs_rq)				\
+	for (; (se) && ((cfs_rq) = cfs_rq_of(se)); (se) = (se)->parent)
 
 static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 {
@@ -453,8 +453,8 @@ static int se_is_idle(struct sched_entit
 
 #else /* !CONFIG_FAIR_GROUP_SCHED: */
 
-#define for_each_sched_entity(se) \
-		for (; se; se = NULL)
+#define for_each_sched_entity(se, cfs_rq) \
+	for (; (se) && ((cfs_rq) = cfs_rq_of(se)); (se) = NULL)
 
 static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 {
@@ -2277,9 +2277,10 @@ static void update_curr(struct cfs_rq *c
 static void update_curr_fair(struct rq *rq)
 {
 	struct sched_entity *se = &rq->donor->se;
+	struct cfs_rq *cfs_rq;
 
-	for_each_sched_entity(se)
-		update_curr(cfs_rq_of(se));
+	for_each_sched_entity(se, cfs_rq)
+		update_curr(cfs_rq);
 }
 
 static inline void
@@ -5011,18 +5012,19 @@ static void reweight_task_fair(struct rq
 {
 	struct sched_entity *se = &p->se;
 	unsigned long weight = NICE_0_LOAD;
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
 
 	if (se->on_rq)
 		update_curr_fair(rq);
 
-	reweight_entity(cfs_rq_of(se), se, lw->weight);
+	reweight_entity(cfs_rq, se, lw->weight);
 	se->load.inv_weight = lw->inv_weight;
 
 	if (!se->on_rq)
 		return;
 
-	for_each_sched_entity(se)
-		weight = __calc_prop_weight(cfs_rq_of(se), se, weight);
+	for_each_sched_entity(se, cfs_rq)
+		weight = __calc_prop_weight(cfs_rq, se, weight);
 
 	reweight_eevdf(&rq->cfs, &p->se, weight, p->se.on_rq);
 }
@@ -6593,6 +6595,8 @@ static __always_inline void return_cfs_r
 
 static void set_delayed(struct sched_entity *se)
 {
+	struct cfs_rq *cfs_rq;
+
 	/*
 	 * Delayed se of cfs_rq have no tasks queued on them.
 	 * Do not adjust h_nr_runnable since __dequeue_task()
@@ -6615,15 +6619,14 @@ static void set_delayed(struct sched_ent
 	pref_llc_running_dec(rq_of(cfs_rq_of(se)), task_of(se));
 	se->sched_delayed = 1;
 
-	for_each_sched_entity(se) {
-		struct cfs_rq *cfs_rq = cfs_rq_of(se);
-
+	for_each_sched_entity(se, cfs_rq)
 		cfs_rq->h_nr_runnable--;
-	}
 }
 
 static void clear_delayed(struct sched_entity *se)
 {
+	struct cfs_rq *cfs_rq;
+
 	se->sched_delayed = 0;
 
 	/*
@@ -6642,11 +6645,8 @@ static void clear_delayed(struct sched_e
 	 */
 	pref_llc_running_inc(rq_of(cfs_rq_of(se)), task_of(se));
 
-	for_each_sched_entity(se) {
-		struct cfs_rq *cfs_rq = cfs_rq_of(se);
-
+	for_each_sched_entity(se, cfs_rq)
 		cfs_rq->h_nr_runnable++;
-	}
 }
 
 static void
@@ -7308,14 +7308,16 @@ void unthrottle_cfs_rq(struct cfs_rq *cf
 	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
 
 	if (!cfs_rq->load.weight) {
+		struct cfs_rq *cfs_rq_se;
+
 		if (!cfs_rq->on_list)
 			return;
 		/*
 		 * Nothing to run but something to decay (on_list)?
 		 * Complete the branch.
 		 */
-		for_each_sched_entity(se) {
-			if (list_add_leaf_cfs_rq(cfs_rq_of(se)))
+		for_each_sched_entity(se, cfs_rq_se) {
+			if (list_add_leaf_cfs_rq(cfs_rq_se))
 				break;
 		}
 	}
@@ -8161,13 +8163,12 @@ static unsigned long enqueue_hierarchy(s
 	struct sched_entity *se = &p->se;
 	int h_nr_idle = task_has_idle_policy(p);
 	int h_nr_runnable = 1;
+	struct cfs_rq *cfs_rq;
 
 	if (task_new && se->sched_delayed)
 		h_nr_runnable = 0;
 
-	for_each_sched_entity(se) {
-		struct cfs_rq *cfs_rq = cfs_rq_of(se);
-
+	for_each_sched_entity(se, cfs_rq) {
 		update_curr(cfs_rq);
 
 		if (!se->on_rq) {
@@ -8286,16 +8287,15 @@ static void dequeue_hierarchy(struct tas
 	bool task_sleep = flags & DEQUEUE_SLEEP;
 	bool task_delayed = flags & DEQUEUE_DELAYED;
 	bool task_throttled = flags & DEQUEUE_THROTTLE;
-	int h_nr_runnable = 0;
 	int h_nr_idle = task_has_idle_policy(p);
+	int h_nr_runnable = 0;
+	struct cfs_rq *cfs_rq;
 	bool dequeue = true;
 
 	if (task_sleep || task_delayed || !se->sched_delayed)
 		h_nr_runnable = 1;
 
-	for_each_sched_entity(se) {
-		struct cfs_rq *cfs_rq = cfs_rq_of(se);
-
+	for_each_sched_entity(se, cfs_rq) {
 		update_curr(cfs_rq);
 
 		if (dequeue) {
@@ -11557,8 +11557,7 @@ static void update_cfs_rq_h_load(struct
 		return;
 
 	WRITE_ONCE(cfs_rq->h_load_next, NULL);
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
+	for_each_sched_entity(se, cfs_rq) {
 		WRITE_ONCE(cfs_rq->h_load_next, se);
 		if (cfs_rq->last_h_load_update == now)
 			break;
@@ -15237,9 +15236,9 @@ static inline void task_tick_core(struct
 static void se_fi_update(const struct sched_entity *se, unsigned int fi_seq,
 			 bool forceidle)
 {
-	for_each_sched_entity(se) {
-		struct cfs_rq *cfs_rq = cfs_rq_of(se);
+	struct cfs_rq *cfs_rq;
 
+	for_each_sched_entity(se, cfs_rq) {
 		if (forceidle) {
 			if (cfs_rq->forceidle_seq == fi_seq)
 				break;
@@ -15317,10 +15316,8 @@ static void task_tick_fair(struct rq *rq
 		unsigned long weight = NICE_0_LOAD;
 		struct cfs_rq *cfs_rq;
 
-		for_each_sched_entity(se) {
-			cfs_rq = cfs_rq_of(se);
+		for_each_sched_entity(se, cfs_rq) {
 			entity_tick(cfs_rq, se, hrtick);
-
 			weight = __calc_prop_weight(cfs_rq, se, weight);
 		}
 
@@ -15402,9 +15399,7 @@ static void propagate_entity_cfs_rq(stru
 	/* Start to propagate at parent */
 	se = se->parent;
 
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-
+	for_each_sched_entity(se, cfs_rq) {
 		update_load_avg(cfs_rq, se, UPDATE_TG);
 
 		if (!cfs_rq_pelt_clock_throttled(cfs_rq))
@@ -15511,9 +15506,7 @@ static void set_next_task_fair(struct rq
 	if (on_rq)
 		__dequeue_entity(cfs_rq, se);
 
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-
+	for_each_sched_entity(se, cfs_rq) {
 		if (!IS_ENABLED(CONFIG_FAIR_GROUP_SCHED) ||
 		    !first || !cfs_rq->h_curr)
 			set_next_entity(cfs_rq, se);
@@ -15720,13 +15713,14 @@ static int __sched_group_set_shares(stru
 	for_each_possible_cpu(i) {
 		struct rq *rq = cpu_rq(i);
 		struct sched_entity *se = tg_se(tg, i);
+		struct cfs_rq *cfs_rq;
 		struct rq_flags rf;
 
 		/* Propagate contribution to hierarchy */
 		rq_lock_irqsave(rq, &rf);
 		update_rq_clock(rq);
-		for_each_sched_entity(se) {
-			update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
+		for_each_sched_entity(se, cfs_rq) {
+			update_load_avg(cfs_rq, se, UPDATE_TG);
 			update_cfs_group(se);
 		}
 		rq_unlock_irqrestore(rq, &rf);
@@ -15773,6 +15767,7 @@ int sched_group_set_idle(struct task_gro
 		struct sched_entity *se = tg_se(tg, i);
 		struct cfs_rq *grp_cfs_rq = tg_cfs_rq(tg, i);
 		bool was_idle = cfs_rq_is_idle(grp_cfs_rq);
+		struct cfs_rq *cfs_rq;
 		long idle_task_delta;
 		struct rq_flags rf;
 
@@ -15787,9 +15782,7 @@ int sched_group_set_idle(struct task_gro
 		if (!cfs_rq_is_idle(grp_cfs_rq))
 			idle_task_delta *= -1;
 
-		for_each_sched_entity(se) {
-			struct cfs_rq *cfs_rq = cfs_rq_of(se);
-
+		for_each_sched_entity(se, cfs_rq) {
 			if (!se->on_rq)
 				break;