linux-kernel - [PATCH] sched/deadline: dome some cleanup for push_dl

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Date:   Tue, 7 Jul 2020 00:04:42 +0800
From:   Peng Liu <iwtbavbm@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de
Subject: [PATCH] sched/deadline: dome some cleanup for push_dl_task()

'commit 840d719604b0 ("sched/deadline: Update rq_clock of later_rq when pushing a task")'
introduced the update_rq_clock() to fix the "used-before-update" bug.

'commit f4904815f97a ("sched/deadline: Fix double accounting of rq/running bw in push & pull")'
took away the bug source(add_running_bw()).

We no longer need to update rq_clock in advance, let activate_task()
worry about that.

Signed-off-by: Peng Liu <iwtbavbm@...il.com>
---
 kernel/sched/deadline.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 504d2f51b0d6..c3fa11f84d93 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2104,13 +2104,7 @@ static int push_dl_task(struct rq *rq)
 
 	deactivate_task(rq, next_task, 0);
 	set_task_cpu(next_task, later_rq->cpu);
-
-	/*
-	 * Update the later_rq clock here, because the clock is used
-	 * by the cpufreq_update_util() inside __add_running_bw().
-	 */
-	update_rq_clock(later_rq);
-	activate_task(later_rq, next_task, ENQUEUE_NOCLOCK);
+	activate_task(later_rq, next_task, 0);
 	ret = 1;
 
 	resched_curr(later_rq);
-- 
2.20.1