[PATCH 1/1] sched/deadline: Kill task_struct->pi_top_task

[Oleg Nesterov]

Remove task_struct->pi_top_task. The only user, rt_mutex_setprio(),
can use a local.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
 include/linux/sched.h |    2 --
 kernel/fork.c         |    1 -
 kernel/sched/core.c   |    6 +++---
 3 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 82fe3da..2b426ee 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1386,8 +1386,6 @@ struct task_struct {
 	struct rb_node *pi_waiters_leftmost;
 	/* Deadlock detection and priority inheritance handling */
 	struct rt_mutex_waiter *pi_blocked_on;
-	/* Top pi_waiters task */
-	struct task_struct *pi_top_task;
 #endif
 
 #ifdef CONFIG_DEBUG_MUTEXES
diff --git a/kernel/fork.c b/kernel/fork.c
index 65736ca..cafea61 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1094,7 +1094,6 @@ static void rt_mutex_init_task(struct task_struct *p)
 	p->pi_waiters = RB_ROOT;
 	p->pi_waiters_leftmost = NULL;
 	p->pi_blocked_on = NULL;
-	p->pi_top_task = NULL;
 #endif
 }
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 268a45e..9dc8517 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2888,7 +2888,6 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 	}
 
 	trace_sched_pi_setprio(p, prio);
-	p->pi_top_task = rt_mutex_get_top_task(p);
 	oldprio = p->prio;
 	prev_class = p->sched_class;
 	on_rq = p->on_rq;
@@ -2908,8 +2907,9 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 	 *          running task
 	 */
 	if (dl_prio(prio)) {
-		if (!dl_prio(p->normal_prio) || (p->pi_top_task &&
-			dl_entity_preempt(&p->pi_top_task->dl, &p->dl))) {
+		struct task_struct *pi_task = rt_mutex_get_top_task(p);
+		if (!dl_prio(p->normal_prio) ||
+		    (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
 			p->dl.dl_boosted = 1;
 			p->dl.dl_throttled = 0;
 			enqueue_flag = ENQUEUE_REPLENISH;
-- 
1.5.5.1


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