[RFC PATCH v6 18/25] sched/rt: Update task's RT runqueue when switching scheduling class

[Yuri Andriaccio <yurand2000@gmail.com>]

Signed-off-by: Yuri Andriaccio <yurand2000@gmail.com>
---
 kernel/sched/rt.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index a32b1f68e645..fc7af6bda3f8 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1897,6 +1897,25 @@ void __init init_sched_rt_class(void)
 	}
 }

+#ifdef CONFIG_RT_GROUP_SCHED
+static void switching_to_rt(struct rq *rq, struct task_struct *p)
+{
+	struct task_group *tg = p->sched_task_group;
+	int cpu = rq->cpu;
+
+	if (tg == &root_task_group)
+		return;
+
+	guard(raw_spinlock_irqsave)(dl_bw_lock_of_tg(tg));
+	if (!rt_group_sched_enabled())
+		tg = &root_task_group;
+
+	p->rt.rt_rq = dl_bandwidth_read(tg)->active_context->rt_rq[cpu];
+}
+#else
+static void switching_to_rt(struct rq *rq, struct task_struct *p) {}
+#endif
+
 /*
  * When switching a task to RT, we may overload the runqueue
  * with RT tasks. In this case we try to push them off to
@@ -2095,6 +2114,7 @@ DEFINE_SCHED_CLASS(rt) = {

 	.get_rr_interval	= get_rr_interval_rt,

+	.switching_to		= switching_to_rt,
 	.switched_to		= switched_to_rt,
 	.prio_changed		= prio_changed_rt,

--
2.54.0