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Subject[PATCH v2] sched/core: Remove unnecessary check for next_task in push_{rt,dl}_task()
Date
In push_{rt,dl}_task(), we call pick_next_pushable{_dl}_task() to
pick next_task before the check. If next_task and rq->curr are equal,
which will trigger BUG_ON() in pick_next_pushable{_dl}_task(). See
the following code in pick_next_pushable{_dl}_task().

static struct task_struct *pick_next_pushable{_dl}_task(struct rq *rq)
{
BUG_ON(task_current(rq, p));
}

The task_current() will check if task p and rq->curr are equal.
So, we can remove the unnecessary check in push_{rt,dl}_task().

Signed-off-by: Muchun Song <smuchun@gmail.com>
---
Changes in v2:
-also remove unnecessary check in deadline.c
-update commit message
---
kernel/sched/deadline.c | 5 -----
kernel/sched/rt.c | 5 -----
2 files changed, 10 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 470ba6b464fe..4b0189627318 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2042,11 +2042,6 @@ static int push_dl_task(struct rq *rq)
return 0;

retry:
- if (unlikely(next_task == rq->curr)) {
- WARN_ON(1);
- return 0;
- }
-
/*
* If next_task preempts rq->curr, and rq->curr
* can move away, it makes sense to just reschedule
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 481bb7aa25c5..ec097edea9ca 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1813,11 +1813,6 @@ static int push_rt_task(struct rq *rq)
return 0;

retry:
- if (unlikely(next_task == rq->curr)) {
- WARN_ON(1);
- return 0;
- }
-
/*
* It's possible that the next_task slipped in of
* higher priority than current. If that's the case
--
2.17.1
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