[PATCH] sched/deadline: fix rq->dl.pushable_tasks bug in push_dl_task()

From: Wanpeng Li
Date: Thu Nov 06 2014 - 02:23:04 EST


Do not call dequeue_pushable_dl_task() when failing to push an eligible
task, as it remains pushable, merely not at this particular moment.
Actually the patch is the same behavior as commit 311e800e16f6 ("sched,
rt: Fix rq->rt.pushable_tasks bug in push_rt_task()" in -rt side.

Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxxxxxx>
---
kernel/sched/deadline.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index f3d7776..00324af 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1331,6 +1331,7 @@ static int push_dl_task(struct rq *rq)
{
struct task_struct *next_task;
struct rq *later_rq;
+ int ret = 0;

if (!rq->dl.overloaded)
return 0;
@@ -1376,7 +1377,6 @@ retry:
* The task is still there. We don't try
* again, some other cpu will pull it when ready.
*/
- dequeue_pushable_dl_task(rq, next_task);
goto out;
}

@@ -1392,6 +1392,7 @@ retry:
deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, later_rq->cpu);
activate_task(later_rq, next_task, 0);
+ ret = 1;

resched_curr(later_rq);

@@ -1400,7 +1401,7 @@ retry:
out:
put_task_struct(next_task);

- return 1;
+ return ret;
}

static void push_dl_tasks(struct rq *rq)
--
1.9.1

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