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Subject[patch 2/2] sched: Protect sched_rr_get_param access to task->sched_class
sched_rr_get_param calls task->sched_class->get_rr_interval(task)
without protection against a concurrent sched_setscheduler() call
which modifies task->sched_class.

Serialize the access with task_rq_lock(task);

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/sched.c | 4 ++++
1 file changed, 4 insertions(+)
Index: linux-2.6-tip/kernel/sched.c
===================================================================
--- linux-2.6-tip.orig/kernel/sched.c
+++ linux-2.6-tip/kernel/sched.c
@@ -6887,6 +6887,8 @@ SYSCALL_DEFINE2(sched_rr_get_interval, p
{
struct task_struct *p;
unsigned int time_slice;
+ unsigned long flags;
+ struct rq *rq;
int retval;
struct timespec t;

@@ -6903,7 +6905,9 @@ SYSCALL_DEFINE2(sched_rr_get_interval, p
if (retval)
goto out_unlock;

+ rq = task_rq_lock(p, &flags);
time_slice = p->sched_class->get_rr_interval(p);
+ task_rq_unlock(rq, &flags);

read_unlock(&tasklist_lock);
jiffies_to_timespec(time_slice, &t);



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