commit 466af29bf4270e84261712428a1304c28e3743fa
author Oleg Nesterov <oleg@redhat.com> Fri Jun 06 18:52:06 2014 +0200
committer Ingo Molnar <mingo@kernel.org> Wed Jul 16 13:38:18 2014 +0200
tree e622633f08aa2fe2bda549cb5686d61451839cf1
parent b728ca06029d085a1585c1926610f26de93b9146

sched/deadline: Kill task_struct->pi_top_task

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

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daeseok Youn <daeseok.youn@gmail.com>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Dempsky <mdempsky@chromium.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20140606165206.GB29465@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 306f4f0..c9c9ff7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1440,8 +1440,6 @@
 	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

kernel/fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index d2799d1..6ff87f442 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1095,7 +1095,6 @@
 	p->pi_waiters = RB_ROOT;
 	p->pi_waiters_leftmost = NULL;
 	p->pi_blocked_on = NULL;
-	p->pi_top_task = NULL;
 #endif
 }
 

kernel/sched/core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2dbc63d..cf7695a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2980,7 +2980,6 @@
 	}
 
 	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;
@@ -3000,8 +2999,9 @@
 	 *          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;