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authorThomas Gleixner <tglx@linutronix.de>2010-02-17 09:05:48 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2010-03-15 09:07:14 -0700
commit371f1d177527b1f815b55a03284ccb2c6dc79c3a (patch)
parent51c80d13a1d86848e178a5a5ea31cb0edfeb3efe (diff)
sched: Don't use possibly stale sched_class
commit 83ab0aa0d5623d823444db82c3b3c34d7ec364ae upstream. setscheduler() saves task->sched_class outside of the rq->lock held region for a check after the setscheduler changes have become effective. That might result in checking a stale value. rtmutex_setprio() has the same problem, though it is protected by p->pi_lock against setscheduler(), but for correctness sake (and to avoid bad examples) it needs to be fixed as well. Retrieve task->sched_class inside of the rq->lock held region. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index e4b69fae2f33..00a59b090e6f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6065,7 +6065,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
unsigned long flags;
int oldprio, on_rq, running;
struct rq *rq;
- const struct sched_class *prev_class = p->sched_class;
+ const struct sched_class *prev_class;
BUG_ON(prio < 0 || prio > MAX_PRIO);
@@ -6073,6 +6073,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
oldprio = p->prio;
+ prev_class = p->sched_class;
on_rq = p->se.on_rq;
running = task_current(rq, p);
if (on_rq)
@@ -6292,7 +6293,7 @@ static int __sched_setscheduler(struct task_struct *p, int policy,
int retval, oldprio, oldpolicy = -1, on_rq, running;
unsigned long flags;
- const struct sched_class *prev_class = p->sched_class;
+ const struct sched_class *prev_class;
struct rq *rq;
int reset_on_fork;
@@ -6406,6 +6407,7 @@ recheck:
p->sched_reset_on_fork = reset_on_fork;
oldprio = p->prio;
+ prev_class = p->sched_class;
__setscheduler(rq, p, policy, param->sched_priority);
if (running)