From eeb2476985465ff49c411fdf1f621aa853eb0e72 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 29 May 2019 20:36:40 +0000
Subject: [PATCH] sched/{rt,deadline}: Fix set_next_task vs pick_next_task

References: bnc#1155798 (CPU scheduler functional and performance backports)
Patch-mainline: v5.4-rc1
Git-commit: f95d4eaee6d0207bff2dc93371133d31227d4cfb

Because pick_next_task() implies set_curr_task() and some of the
details haven't mattered too much, some of what _should_ be in
set_curr_task() ended up in pick_next_task, correct this.

This prepares the way for a pick_next_task() variant that does not
affect the current state; allowing remote picking.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aaron Lu <aaron.lwe@gmail.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: mingo@kernel.org
Cc: Phil Auld <pauld@redhat.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Link: https://lkml.kernel.org/r/38c61d5240553e043c27c5e00b9dd0d184dd6081.1559129225.git.vpillai@digitalocean.com
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/sched/deadline.c | 22 +++++++++++-----------
 kernel/sched/rt.c       | 26 +++++++++++++-------------
 2 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 6dafaabde1d6..baa0754e81c0 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1727,12 +1727,20 @@ static void start_hrtick_dl(struct rq *rq, struct task_struct *p)
 }
 #endif
 
-static inline void set_next_task(struct rq *rq, struct task_struct *p)
+static void set_next_task_dl(struct rq *rq, struct task_struct *p)
 {
 	p->se.exec_start = rq_clock_task(rq);
 
 	/* You can't push away the running task */
 	dequeue_pushable_dl_task(rq, p);
+
+	if (hrtick_enabled(rq))
+		start_hrtick_dl(rq, p);
+
+	if (rq->curr->sched_class != &dl_sched_class)
+		update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+
+	deadline_queue_push_tasks(rq);
 }
 
 static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
@@ -1791,15 +1799,7 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 
 	p = dl_task_of(dl_se);
 
-	set_next_task(rq, p);
-
-	if (hrtick_enabled(rq))
-		start_hrtick_dl(rq, p);
-
-	deadline_queue_push_tasks(rq);
-
-	if (rq->curr->sched_class != &dl_sched_class)
-		update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+	set_next_task_dl(rq, p);
 
 	return p;
 }
@@ -1846,7 +1846,7 @@ static void task_fork_dl(struct task_struct *p)
 
 static void set_curr_task_dl(struct rq *rq)
 {
-	set_next_task(rq, rq->curr);
+	set_next_task_dl(rq, rq->curr);
 }
 
 #ifdef CONFIG_SMP
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index a532558a5176..40bb71004325 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1498,12 +1498,22 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flag
 #endif
 }
 
-static inline void set_next_task(struct rq *rq, struct task_struct *p)
+static inline void set_next_task_rt(struct rq *rq, struct task_struct *p)
 {
 	p->se.exec_start = rq_clock_task(rq);
 
 	/* The running task is never eligible for pushing */
 	dequeue_pushable_task(rq, p);
+
+	/*
+	 * If prev task was rt, put_prev_task() has already updated the
+	 * utilization. We only care of the case where we start to schedule a
+	 * rt task
+	 */
+	if (rq->curr->sched_class != &rt_sched_class)
+		update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+
+	rt_queue_push_tasks(rq);
 }
 
 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
@@ -1577,17 +1587,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 
 	p = _pick_next_task_rt(rq);
 
-	set_next_task(rq, p);
-
-	rt_queue_push_tasks(rq);
-
-	/*
-	 * If prev task was rt, put_prev_task() has already updated the
-	 * utilization. We only care of the case where we start to schedule a
-	 * rt task
-	 */
-	if (rq->curr->sched_class != &rt_sched_class)
-		update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
+	set_next_task_rt(rq, p);
 
 	return p;
 }
@@ -2356,7 +2356,7 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
 
 static void set_curr_task_rt(struct rq *rq)
 {
-	set_next_task(rq, rq->curr);
+	set_next_task_rt(rq, rq->curr);
 }
 
 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)