Subject: sched: Have migrate_disable ignore bounded threads
Date: Tue, 27 Sep 2011 08:40:25 -0400
From: Peter Zijlstra <a.p.zijlstra@chello.nl>

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Clark Williams <williams@redhat.com>
Link: http://lkml.kernel.org/r/20110927124423.567944215@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 kernel/sched/core.c |   23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

Index: linux-stable/kernel/sched/core.c
===================================================================
--- linux-stable.orig/kernel/sched/core.c
+++ linux-stable/kernel/sched/core.c
@@ -3410,7 +3410,7 @@ void migrate_disable(void)
 {
 	struct task_struct *p = current;
 
-	if (in_atomic()) {
+	if (in_atomic() || p->flags & PF_THREAD_BOUND) {
 #ifdef CONFIG_SCHED_DEBUG
 		p->migrate_disable_atomic++;
 #endif
@@ -3441,7 +3441,7 @@ void migrate_enable(void)
 	unsigned long flags;
 	struct rq *rq;
 
-	if (in_atomic()) {
+	if (in_atomic() || p->flags & PF_THREAD_BOUND) {
 #ifdef CONFIG_SCHED_DEBUG
 		p->migrate_disable_atomic--;
 #endif
@@ -3462,26 +3462,21 @@ void migrate_enable(void)
 
 	if (unlikely(migrate_disabled_updated(p))) {
 		/*
-		 * See comment in update_migrate_disable() about locking.
+		 * Undo whatever update_migrate_disable() did, also see there
+		 * about locking.
 		 */
 		rq = this_rq();
 		raw_spin_lock_irqsave(&rq->lock, flags);
-		mask = tsk_cpus_allowed(p);
+
 		/*
 		 * Clearing migrate_disable causes tsk_cpus_allowed to
 		 * show the tasks original cpu affinity.
 		 */
 		p->migrate_disable = 0;
-
-		WARN_ON(!cpumask_test_cpu(smp_processor_id(), mask));
-
-		if (unlikely(!cpumask_equal(&p->cpus_allowed, mask))) {
-			/* Get the mask now that migration is enabled */
-			mask = tsk_cpus_allowed(p);
-			if (p->sched_class->set_cpus_allowed)
-				p->sched_class->set_cpus_allowed(p, mask);
-			p->nr_cpus_allowed = cpumask_weight(mask);
-		}
+		mask = tsk_cpus_allowed(p);
+		if (p->sched_class->set_cpus_allowed)
+			p->sched_class->set_cpus_allowed(p, mask);
+		p->nr_cpus_allowed = cpumask_weight(mask);
 		raw_spin_unlock_irqrestore(&rq->lock, flags);
 	} else
 		p->migrate_disable = 0;