From: Peter Zijlstra (Intel) <[email protected]>

In preparation of further separating pick_next_task() and
set_curr_task() we have to pass the actual task into it, while there,
rename the thing to better pair with put_prev_task().

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
---
 kernel/sched/core.c      | 12 ++++++------
 kernel/sched/deadline.c  |  7 +------
 kernel/sched/fair.c      | 17 ++++++++++++++---
 kernel/sched/idle.c      | 27 +++++++++++++++------------
 kernel/sched/rt.c        |  7 +------
 kernel/sched/sched.h     |  8 +++++---
 kernel/sched/stop_task.c | 17 +++++++----------
 7 files changed, 49 insertions(+), 46 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6f4861ae85dc..32ea79fb8d29 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1081,7 +1081,7 @@ void do_set_cpus_allowed(struct task_struct *p, const 
struct cpumask *new_mask)
        if (queued)
                enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
        if (running)
-               set_curr_task(rq, p);
+               set_next_task(rq, p);
 }
 
 /*
@@ -3890,7 +3890,7 @@ void rt_mutex_setprio(struct task_struct *p, struct 
task_struct *pi_task)
        if (queued)
                enqueue_task(rq, p, queue_flag);
        if (running)
-               set_curr_task(rq, p);
+               set_next_task(rq, p);
 
        check_class_changed(rq, p, prev_class, oldprio);
 out_unlock:
@@ -3957,7 +3957,7 @@ void set_user_nice(struct task_struct *p, long nice)
                        resched_curr(rq);
        }
        if (running)
-               set_curr_task(rq, p);
+               set_next_task(rq, p);
 out_unlock:
        task_rq_unlock(rq, p, &rf);
 }
@@ -4382,7 +4382,7 @@ static int __sched_setscheduler(struct task_struct *p,
                enqueue_task(rq, p, queue_flags);
        }
        if (running)
-               set_curr_task(rq, p);
+               set_next_task(rq, p);
 
        check_class_changed(rq, p, prev_class, oldprio);
 
@@ -5555,7 +5555,7 @@ void sched_setnuma(struct task_struct *p, int nid)
        if (queued)
                enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
        if (running)
-               set_curr_task(rq, p);
+               set_next_task(rq, p);
        task_rq_unlock(rq, p, &rf);
 }
 #endif /* CONFIG_NUMA_BALANCING */
@@ -6438,7 +6438,7 @@ void sched_move_task(struct task_struct *tsk)
        if (queued)
                enqueue_task(rq, tsk, queue_flags);
        if (running)
-               set_curr_task(rq, tsk);
+               set_next_task(rq, tsk);
 
        task_rq_unlock(rq, tsk, &rf);
 }
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index b8e15c7aa889..fadfbfe7d573 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1813,11 +1813,6 @@ static void task_fork_dl(struct task_struct *p)
         */
 }
 
-static void set_curr_task_dl(struct rq *rq)
-{
-       set_next_task_dl(rq, rq->curr);
-}
-
 #ifdef CONFIG_SMP
 
 /* Only try algorithms three times */
@@ -2405,6 +2400,7 @@ const struct sched_class dl_sched_class = {
 
        .pick_next_task         = pick_next_task_dl,
        .put_prev_task          = put_prev_task_dl,
+       .set_next_task          = set_next_task_dl,
 
 #ifdef CONFIG_SMP
        .select_task_rq         = select_task_rq_dl,
@@ -2415,7 +2411,6 @@ const struct sched_class dl_sched_class = {
        .task_woken             = task_woken_dl,
 #endif
 
-       .set_curr_task          = set_curr_task_dl,
        .task_tick              = task_tick_dl,
        .task_fork              = task_fork_dl,
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1ccab35ccf21..ebad19a033eb 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10359,9 +10359,19 @@ static void switched_to_fair(struct rq *rq, struct 
task_struct *p)
  * This routine is mostly called to set cfs_rq->curr field when a task
  * migrates between groups/classes.
  */
-static void set_curr_task_fair(struct rq *rq)
+static void set_next_task_fair(struct rq *rq, struct task_struct *p)
 {
-       struct sched_entity *se = &rq->curr->se;
+       struct sched_entity *se = &p->se;
+
+#ifdef CONFIG_SMP
+       if (task_on_rq_queued(p)) {
+               /*
+                * Move the next running task to the front of the list, so our
+                * cfs_tasks list becomes MRU one.
+                */
+               list_move(&se->group_node, &rq->cfs_tasks);
+       }
+#endif
 
        for_each_sched_entity(se) {
                struct cfs_rq *cfs_rq = cfs_rq_of(se);
@@ -10632,7 +10642,9 @@ const struct sched_class fair_sched_class = {
        .check_preempt_curr     = check_preempt_wakeup,
 
        .pick_next_task         = pick_next_task_fair,
+
        .put_prev_task          = put_prev_task_fair,
+       .set_next_task          = set_next_task_fair,
 
 #ifdef CONFIG_SMP
        .select_task_rq         = select_task_rq_fair,
@@ -10645,7 +10657,6 @@ const struct sched_class fair_sched_class = {
        .set_cpus_allowed       = set_cpus_allowed_common,
 #endif
 
-       .set_curr_task          = set_curr_task_fair,
        .task_tick              = task_tick_fair,
        .task_fork              = task_fork_fair,
 
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 39788d3a40ec..dd64be34881d 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -373,14 +373,25 @@ static void check_preempt_curr_idle(struct rq *rq, struct 
task_struct *p, int fl
        resched_curr(rq);
 }
 
+static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
+{
+}
+
+static void set_next_task_idle(struct rq *rq, struct task_struct *next)
+{
+       update_idle_core(rq);
+       schedstat_inc(rq->sched_goidle);
+}
+
 static struct task_struct *
 pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags 
*rf)
 {
+       struct task_struct *next = rq->idle;
+
        put_prev_task(rq, prev);
-       update_idle_core(rq);
-       schedstat_inc(rq->sched_goidle);
+       set_next_task_idle(rq, next);
 
-       return rq->idle;
+       return next;
 }
 
 /*
@@ -396,10 +407,6 @@ dequeue_task_idle(struct rq *rq, struct task_struct *p, 
int flags)
        raw_spin_lock_irq(rq_lockp(rq));
 }
 
-static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
-{
-}
-
 /*
  * scheduler tick hitting a task of our scheduling class.
  *
@@ -412,10 +419,6 @@ static void task_tick_idle(struct rq *rq, struct 
task_struct *curr, int queued)
 {
 }
 
-static void set_curr_task_idle(struct rq *rq)
-{
-}
-
 static void switched_to_idle(struct rq *rq, struct task_struct *p)
 {
        BUG();
@@ -450,13 +453,13 @@ const struct sched_class idle_sched_class = {
 
        .pick_next_task         = pick_next_task_idle,
        .put_prev_task          = put_prev_task_idle,
+       .set_next_task          = set_next_task_idle,
 
 #ifdef CONFIG_SMP
        .select_task_rq         = select_task_rq_idle,
        .set_cpus_allowed       = set_cpus_allowed_common,
 #endif
 
-       .set_curr_task          = set_curr_task_idle,
        .task_tick              = task_tick_idle,
 
        .get_rr_interval        = get_rr_interval_idle,
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 353ad960691b..adec98a94f2b 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2355,11 +2355,6 @@ 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_rt(rq, rq->curr);
-}
-
 static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
 {
        /*
@@ -2381,6 +2376,7 @@ const struct sched_class rt_sched_class = {
 
        .pick_next_task         = pick_next_task_rt,
        .put_prev_task          = put_prev_task_rt,
+       .set_next_task          = set_next_task_rt,
 
 #ifdef CONFIG_SMP
        .select_task_rq         = select_task_rq_rt,
@@ -2392,7 +2388,6 @@ const struct sched_class rt_sched_class = {
        .switched_from          = switched_from_rt,
 #endif
 
-       .set_curr_task          = set_curr_task_rt,
        .task_tick              = task_tick_rt,
 
        .get_rr_interval        = get_rr_interval_rt,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c4cd252dba29..fb01c77c16ff 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1672,6 +1672,7 @@ struct sched_class {
                                               struct task_struct *prev,
                                               struct rq_flags *rf);
        void (*put_prev_task)(struct rq *rq, struct task_struct *p);
+       void (*set_next_task)(struct rq *rq, struct task_struct *p);
 
 #ifdef CONFIG_SMP
        int  (*select_task_rq)(struct task_struct *p, int task_cpu, int 
sd_flag, int flags);
@@ -1686,7 +1687,6 @@ struct sched_class {
        void (*rq_offline)(struct rq *rq);
 #endif
 
-       void (*set_curr_task)(struct rq *rq);
        void (*task_tick)(struct rq *rq, struct task_struct *p, int queued);
        void (*task_fork)(struct task_struct *p);
        void (*task_dead)(struct task_struct *p);
@@ -1716,12 +1716,14 @@ struct sched_class {
 
 static inline void put_prev_task(struct rq *rq, struct task_struct *prev)
 {
+       WARN_ON_ONCE(rq->curr != prev);
        prev->sched_class->put_prev_task(rq, prev);
 }
 
-static inline void set_curr_task(struct rq *rq, struct task_struct *curr)
+static inline void set_next_task(struct rq *rq, struct task_struct *next)
 {
-       curr->sched_class->set_curr_task(rq);
+       WARN_ON_ONCE(rq->curr != next);
+       next->sched_class->set_next_task(rq, next);
 }
 
 #ifdef CONFIG_SMP
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index c183b790ca54..47a3d2a18a9a 100644
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -23,6 +23,11 @@ check_preempt_curr_stop(struct rq *rq, struct task_struct 
*p, int flags)
        /* we're never preempted */
 }
 
+static void set_next_task_stop(struct rq *rq, struct task_struct *stop)
+{
+       stop->se.exec_start = rq_clock_task(rq);
+}
+
 static struct task_struct *
 pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags 
*rf)
 {
@@ -32,8 +37,7 @@ pick_next_task_stop(struct rq *rq, struct task_struct *prev, 
struct rq_flags *rf
                return NULL;
 
        put_prev_task(rq, prev);
-
-       stop->se.exec_start = rq_clock_task(rq);
+       set_next_task_stop(rq, stop);
 
        return stop;
 }
@@ -86,13 +90,6 @@ static void task_tick_stop(struct rq *rq, struct task_struct 
*curr, int queued)
 {
 }
 
-static void set_curr_task_stop(struct rq *rq)
-{
-       struct task_struct *stop = rq->stop;
-
-       stop->se.exec_start = rq_clock_task(rq);
-}
-
 static void switched_to_stop(struct rq *rq, struct task_struct *p)
 {
        BUG(); /* its impossible to change to this class */
@@ -128,13 +125,13 @@ const struct sched_class stop_sched_class = {
 
        .pick_next_task         = pick_next_task_stop,
        .put_prev_task          = put_prev_task_stop,
+       .set_next_task          = set_next_task_stop,
 
 #ifdef CONFIG_SMP
        .select_task_rq         = select_task_rq_stop,
        .set_cpus_allowed       = set_cpus_allowed_common,
 #endif
 
-       .set_curr_task          = set_curr_task_stop,
        .task_tick              = task_tick_stop,
 
        .get_rr_interval        = get_rr_interval_stop,
-- 
2.17.1

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