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sched: Make sure task has correct sched_class after policy change

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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>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1257880321.4108.457.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-11-10 20:12:01 +01:00 • committed by Ingo Molnar
commit ffd44db5f0
1 changed files with 4 additions and 12 deletions
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16
kernel/sched.c
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@ -6159,22 +6159,14 @@ __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);
}