From 8232cd93d321d773fbd6dff634f4dcf888a3e962 Mon Sep 17 00:00:00 2001
From: Johnlay Park <jonglae.park@samsung.com>
Date: Tue, 27 Feb 2018 21:53:22 +0900
Subject: [PATCH] [COMMON] sched/rt: fix !CONFIG_64BIT last_update_time update

Special care must be given to last_update_time on 32BIT
configurations. Add such special treatment as in FAIR.

CAUTIONS: not actually tested on !CONFIG_64BIT

refer the I5728e02a00670ad20f93b4fe9b2d0ea697a66b87

Change-Id: I490c62b207e452f881b8acd07252aa4408b2fa83
Signed-off-by: Johnlay Park <jonglae.park@samsung.com>
---
 kernel/sched/fair.c  |  5 +++++
 kernel/sched/rt.c    | 51 ++++++++++++++++++++++++++++++++++++++++++++
 kernel/sched/sched.h | 13 +++++++++++
 3 files changed, 69 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0f71c8ef6385..e2a849be4c34 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3417,6 +3417,11 @@ int update_rt_rq_load_avg(u64 now, int cpu, struct rt_rq *rt_rq, int running)
 	 */
 	ret = ___update_load_avg(now, cpu, sa, 0, running, NULL, rt_rq);
 
+#ifndef CONFIG_64BIT
+	smp_wmb();
+	rt_rq->load_last_update_time_copy = sa->last_update_time;
+#endif
+
 	return ret;
 }
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index cc07931eb4a1..bd0217c2e983 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1573,6 +1573,57 @@ out:
 	return cpu;
 }
 
+#ifdef CONFIG_RT_GROUP_SCHED
+/*
+ * Called within set_task_rq() right before setting a task's cpu. The
+ * caller only guarantees p->pi_lock is held; no other assumptions,
+ * including the state of rq->lock, should be made.
+ */
+void set_task_rq_rt(struct sched_rt_entity *rt_se,
+				    struct rt_rq *prev, struct rt_rq *next)
+{
+	u64 p_last_update_time;
+	u64 n_last_update_time;
+
+	if (!sched_feat(ATTACH_AGE_LOAD))
+		return;
+	/*
+	 * We are supposed to update the task to "current" time, then its up to
+	 * date and ready to go to new CPU/rt_rq. But we have difficulty in
+	 * getting what current time is, so simply throw away the out-of-date
+	 * time. This will result in the wakee task is less decayed, but giving
+	 * the wakee more load sounds not bad.
+	 */
+	if (!(rt_se->avg.last_update_time && prev))
+		return;
+#ifndef CONFIG_64BIT
+	{
+		u64 p_last_update_time_copy;
+		u64 n_last_update_time_copy;
+
+		do {
+			p_last_update_time_copy = prev->load_last_update_time_copy;
+			n_last_update_time_copy = next->load_last_update_time_copy;
+
+			smp_rmb();
+
+			p_last_update_time = prev->avg.last_update_time;
+			n_last_update_time = next->avg.last_update_time;
+
+		} while (p_last_update_time != p_last_update_time_copy ||
+			 n_last_update_time != n_last_update_time_copy);
+	}
+#else
+	p_last_update_time = prev->avg.last_update_time;
+	n_last_update_time = next->avg.last_update_time;
+#endif
+	__update_load_avg(p_last_update_time, cpu_of(rq_of_rt_rq(prev)),
+		&rt_se->avg, 0, 0, NULL);
+
+	rt_se->avg.last_update_time = n_last_update_time;
+}
+#endif /* CONFIG_RT_GROUP_SCHED */
+
 #ifndef CONFIG_64BIT
 static inline u64 rt_rq_last_update_time(struct rt_rq *rt_rq)
 {
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 447abeba7f29..6e88be5d98be 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -438,6 +438,16 @@ extern void sched_move_task(struct task_struct *tsk);
 #ifdef CONFIG_FAIR_GROUP_SCHED
 extern int sched_group_set_shares(struct task_group *tg, unsigned long shares);
 
+#ifdef CONFIG_RT_GROUP_SCHED
+#ifdef CONFIG_SMP
+extern void set_task_rq_rt(struct sched_rt_entity *rt_se,
+			    struct rt_rq *prev, struct rt_rq *next);
+#else /* !CONFIG_SMP */
+static inline void set_task_rq_rt(struct sched_rt_entity *rt_se,
+				struct rt_rq *prev, struct rt_rq *next) { }
+#endif /* CONFIG_SMP */
+#endif /* CONFIG_RT_GROUP_SCHED */
+
 #ifdef CONFIG_SMP
 extern void set_task_rq_fair(struct sched_entity *se,
 			     struct cfs_rq *prev, struct cfs_rq *next);
@@ -583,6 +593,9 @@ struct rt_rq {
 
 	struct rq *rq;
 	struct task_group *tg;
+#ifndef CONFIG_64BIT
+		u64 load_last_update_time_copy;
+#endif
 #endif
 };
 
-- 
2.20.1