[tip:sched/urgent] sched: Make sure task has correct sched_class after policy change

[tip-bot for Peter Zijlstra <a.p.zijlstra@chello.nl>]

Commit-ID:  67d08dfed042855431dc99c9e0e6f6f7e85737ef
Gitweb:     http://git.kernel.org/tip/67d08dfed042855431dc99c9e0e6f6f7e85737ef
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Mon, 12 Oct 2009 17:20:54 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 14 Oct 2009 15:02:35 +0200

sched: Make sure task has correct sched_class after policy change

>From the code in rt_mutex_setprio(), it is evident that the
intention is that task's with a RT 'prio' value as a consequence of
receiving a PI boost also have their 'sched_class' field set to
'&rt_sched_class'.

However, Peter noticed that the code in __setscheduler() could
result in this intention being frustrated. Fix it.

Reported-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1253687579.7695.89.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/sched.c |   17 ++++-------------
 1 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 789001d..2d7a002 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6145,23 +6145,14 @@ __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
 {
 	BUG_ON(p->se.on_rq);
 
-	p->policy = policy;
-	switch (p->policy) {
-	case SCHED_NORMAL:
-	case SCHED_BATCH:
-	case SCHED_IDLE:
-		p->sched_class = &fair_sched_class;
-		break;
-	case SCHED_FIFO:
-	case SCHED_RR:
-		p->sched_class = &rt_sched_class;
-		break;
-	}
-
 	p->rt_priority = prio;
 	p->normal_prio = normal_prio(p);
 	/* we are holding p->pi_lock already */
 	p->prio = rt_mutex_getprio(p);
+	if (rt_prio(p->prio))
+		p->sched_class = &rt_sched_class;
+	else
+		p->sched_class = &fair_sched_class;
 	set_load_weight(p);
 }