[PATCH v2 3/5] sched: Remove double_rq_lock() from __migrate_task()

From: Kirill Tkhai
Date: Sat Jul 26 2014 - 10:59:39 EST


Let's use ONRQ_MIGRATING instead.

Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
---
kernel/sched/core.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 772f791..9bfc4a9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4693,20 +4693,20 @@ EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
*/
static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
{
- struct rq *rq_dest, *rq_src;
+ struct rq *rq;
int ret = 0;

if (unlikely(!cpu_active(dest_cpu)))
return ret;

- rq_src = cpu_rq(src_cpu);
- rq_dest = cpu_rq(dest_cpu);
+ rq = cpu_rq(src_cpu);

raw_spin_lock(&p->pi_lock);
- double_rq_lock(rq_src, rq_dest);
+ raw_spin_lock(&rq->lock);
/* Already moved. */
if (task_cpu(p) != src_cpu)
goto done;
+
/* Affinity changed (again). */
if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
goto fail;
@@ -4716,15 +4716,22 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
* placed properly.
*/
if (task_queued(p)) {
- dequeue_task(rq_src, p, 0);
+ dequeue_task(rq, p, 0);
+ p->on_rq = ONRQ_MIGRATING;
set_task_cpu(p, dest_cpu);
- enqueue_task(rq_dest, p, 0);
- check_preempt_curr(rq_dest, p, 0);
+ raw_spin_unlock(&rq->lock);
+
+ rq = cpu_rq(dest_cpu);
+ raw_spin_lock(&rq->lock);
+ BUG_ON(task_rq(p) != rq);
+ p->on_rq = ONRQ_QUEUED;
+ enqueue_task(rq, p, 0);
+ check_preempt_curr(rq, p, 0);
}
done:
ret = 1;
fail:
- double_rq_unlock(rq_src, rq_dest);
+ raw_spin_unlock(&rq->lock);
raw_spin_unlock(&p->pi_lock);
return ret;
}

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/