[RFC][PATCH 04/13] sched/{rt,deadline}: Fix set_next_task vs pick_next_task

[Peter Zijlstra]

Because pick_next_task() implies set_curr_task() and some of the
details haven't matter 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) <pet...@infradead.org>
---
 kernel/sched/deadline.c |   23 ++++++++++++-----------
 kernel/sched/rt.c       |   27 ++++++++++++++-------------
 2 files changed, 26 insertions(+), 24 deletions(-)

--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1694,12 +1694,21 @@ static void start_hrtick_dl(struct rq *r
 }
 #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);
+
+       if (rq->curr != p)
+               deadline_queue_push_tasks(rq);
 }
 
 static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq,
@@ -1758,15 +1767,7 @@ pick_next_task_dl(struct rq *rq, struct
 
        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;
 }
@@ -1813,7 +1814,7 @@ static void task_fork_dl(struct task_str
 
 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
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1498,12 +1498,23 @@ static void check_preempt_curr_rt(struct
 #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);
+
+       if (rq->curr != p)
+               rt_queue_push_tasks(rq);
 }
 
 static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
@@ -1577,17 +1588,7 @@ pick_next_task_rt(struct rq *rq, struct
 
        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 +2357,7 @@ static void task_tick_rt(struct rq *rq,
 
 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)