[PATCH v11 4/7] sched: Add move_queued_task_locked helper

[John Stultz]

From: Connor O'Brien <connoro@xxxxxxxxxx>

Switch logic that deactivates, sets the task cpu,
and reactivates a task on a different rq to use a
helper that will be later extended to push entire
blocked task chains.

This patch was broken out from a larger chain migration
patch originally by Connor O'Brien.

Cc: Joel Fernandes <joelaf@xxxxxxxxxx>
Cc: Qais Yousef <qyousef@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Zimuzo Ezeozue <zezeozue@xxxxxxxxxx>
Cc: Youssef Esmat <youssefesmat@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Metin Kaya <Metin.Kaya@xxxxxxx>
Cc: Xuewen Yan <xuewen.yan94@xxxxxxxxx>
Cc: K Prateek Nayak <kprateek.nayak@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: kernel-team@xxxxxxxxxxx
Signed-off-by: Connor O'Brien <connoro@xxxxxxxxxx>
[jstultz: split out from larger chain migration patch]
Signed-off-by: John Stultz <jstultz@xxxxxxxxxx>
Tested-by: K Prateek Nayak <kprateek.nayak@xxxxxxx>
Tested-by: Metin Kaya <metin.kaya@xxxxxxx>
Reviewed-by: Metin Kaya <metin.kaya@xxxxxxx>
Reviewed-by: Valentin Schneider <vschneid@xxxxxxxxxx>
Reviewed-by: Qais Yousef <qyousef@xxxxxxxxxxx>
---
v8:
* Renamed from push_task_chain to do_push_task so it makes
  more sense without proxy-execution
v10:
* Changed name to move_queued_task_locked as suggested by Valentin
v11:
* Also use new helper in __migrate_swap_task() and
  try_steal_cookie() as suggested by Qais Yousef
* Nit cleanups suggested by Metin
---
 kernel/sched/core.c     | 13 +++----------
 kernel/sched/deadline.c |  8 ++------
 kernel/sched/rt.c       |  8 ++------
 kernel/sched/sched.h    | 12 ++++++++++++
 4 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bcf2c4cc0522..5e63dbcbc1f0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2712,9 +2712,7 @@ int push_cpu_stop(void *arg)
 
 	// XXX validate p is still the highest prio task
 	if (task_rq(p) == rq) {
-		deactivate_task(rq, p, 0);
-		set_task_cpu(p, lowest_rq->cpu);
-		activate_task(lowest_rq, p, 0);
+		move_queued_task_locked(rq, lowest_rq, p);
 		resched_curr(lowest_rq);
 	}
 
@@ -3414,9 +3412,7 @@ static void __migrate_swap_task(struct task_struct *p, int cpu)
 		rq_pin_lock(src_rq, &srf);
 		rq_pin_lock(dst_rq, &drf);
 
-		deactivate_task(src_rq, p, 0);
-		set_task_cpu(p, cpu);
-		activate_task(dst_rq, p, 0);
+		move_queued_task_locked(src_rq, dst_rq, p);
 		wakeup_preempt(dst_rq, p, 0);
 
 		rq_unpin_lock(dst_rq, &drf);
@@ -6369,10 +6365,7 @@ static bool try_steal_cookie(int this, int that)
 		if (sched_task_is_throttled(p, this))
 			goto next;
 
-		deactivate_task(src, p, 0);
-		set_task_cpu(p, this);
-		activate_task(dst, p, 0);
-
+		move_queued_task_locked(src, dst, p);
 		resched_curr(dst);
 
 		success = true;
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index c75d1307d86d..3e05e239f5f6 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2442,9 +2442,7 @@ static int push_dl_task(struct rq *rq)
 		goto retry;
 	}
 
-	deactivate_task(rq, next_task, 0);
-	set_task_cpu(next_task, later_rq->cpu);
-	activate_task(later_rq, next_task, 0);
+	move_queued_task_locked(rq, later_rq, next_task);
 	ret = 1;
 
 	resched_curr(later_rq);
@@ -2530,9 +2528,7 @@ static void pull_dl_task(struct rq *this_rq)
 			if (is_migration_disabled(p)) {
 				push_task = get_push_task(src_rq);
 			} else {
-				deactivate_task(src_rq, p, 0);
-				set_task_cpu(p, this_cpu);
-				activate_task(this_rq, p, 0);
+				move_queued_task_locked(src_rq, this_rq, p);
 				dmin = p->dl.deadline;
 				resched = true;
 			}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index aa4c1c874fa4..55bb33f367ad 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2105,9 +2105,7 @@ static int push_rt_task(struct rq *rq, bool pull)
 		goto retry;
 	}
 
-	deactivate_task(rq, next_task, 0);
-	set_task_cpu(next_task, lowest_rq->cpu);
-	activate_task(lowest_rq, next_task, 0);
+	move_queued_task_locked(rq, lowest_rq, next_task);
 	resched_curr(lowest_rq);
 	ret = 1;
 
@@ -2378,9 +2376,7 @@ static void pull_rt_task(struct rq *this_rq)
 			if (is_migration_disabled(p)) {
 				push_task = get_push_task(src_rq);
 			} else {
-				deactivate_task(src_rq, p, 0);
-				set_task_cpu(p, this_cpu);
-				activate_task(this_rq, p, 0);
+				move_queued_task_locked(src_rq, this_rq, p);
 				resched = true;
 			}
 			/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index a831af102070..a24286059a6a 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3479,5 +3479,17 @@ static inline void init_sched_mm_cid(struct task_struct *t) { }
 
 extern u64 avg_vruntime(struct cfs_rq *cfs_rq);
 extern int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se);
+#ifdef CONFIG_SMP
+static inline
+void move_queued_task_locked(struct rq *src_rq, struct rq *dst_rq, struct task_struct *task)
+{
+	lockdep_assert_rq_held(src_rq);
+	lockdep_assert_rq_held(dst_rq);
+
+	deactivate_task(src_rq, task, 0);
+	set_task_cpu(task, dst_rq->cpu);
+	activate_task(dst_rq, task, 0);
+}
+#endif
 
 #endif /* _KERNEL_SCHED_SCHED_H */
-- 
2.45.2.993.g49e7a77208-goog