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authorThomas Gleixner <tglx@linutronix.de>2009-12-09 09:32:03 +0100
committerIngo Molnar <mingo@elte.hu>2009-12-09 10:01:07 +0100
commitdba091b9e3522b9d32fc9975e48d3b69633b45f0 (patch)
tree91549e3921971b6d0074fd34c29223b593381c8a
parent3160568371da441b7f2fb57f2f1225404207e8f2 (diff)
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) and hand the rq pointer into get_rr_interval() as it's needed at least in the sched_fair implementation. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <alpine.LFD.2.00.0912090930120.3089@localhost.localdomain> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/sched.h3
-rw-r--r--kernel/sched.c6
-rw-r--r--kernel/sched_fair.c6
-rw-r--r--kernel/sched_idletask.c2
-rw-r--r--kernel/sched_rt.c2
5 files changed, 10 insertions, 9 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 89115ec7d43..9b240272508 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1111,7 +1111,8 @@ struct sched_class {
void (*prio_changed) (struct rq *this_rq, struct task_struct *task,
int oldprio, int running);
- unsigned int (*get_rr_interval) (struct task_struct *task);
+ unsigned int (*get_rr_interval) (struct rq *rq,
+ struct task_struct *task);
#ifdef CONFIG_FAIR_GROUP_SCHED
void (*moved_group) (struct task_struct *p);
diff --git a/kernel/sched.c b/kernel/sched.c
index c4635f74540..68db5a2e654 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6887,6 +6887,8 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
{
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, pid_t, pid,
if (retval)
goto out_unlock;
- time_slice = p->sched_class->get_rr_interval(p);
+ rq = task_rq_lock(p, &flags);
+ time_slice = p->sched_class->get_rr_interval(rq, p);
+ task_rq_unlock(rq, &flags);
read_unlock(&tasklist_lock);
jiffies_to_timespec(time_slice, &t);
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index f61837ad336..613c1c74967 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -2014,21 +2014,17 @@ static void moved_group_fair(struct task_struct *p)
}
#endif
-unsigned int get_rr_interval_fair(struct task_struct *task)
+unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
{
struct sched_entity *se = &task->se;
- unsigned long flags;
- struct rq *rq;
unsigned int rr_interval = 0;
/*
* Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
* idle runqueue:
*/
- rq = task_rq_lock(task, &flags);
if (rq->cfs.load.weight)
rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
- task_rq_unlock(rq, &flags);
return rr_interval;
}
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index b133a28fcde..33d5384a73a 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -97,7 +97,7 @@ static void prio_changed_idle(struct rq *rq, struct task_struct *p,
check_preempt_curr(rq, p, 0);
}
-unsigned int get_rr_interval_idle(struct task_struct *task)
+unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
{
return 0;
}
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 5c5fef37841..aecbd9c6b20 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1721,7 +1721,7 @@ static void set_curr_task_rt(struct rq *rq)
dequeue_pushable_task(rq, p);
}
-unsigned int get_rr_interval_rt(struct task_struct *task)
+unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
{
/*
* Time slice is 0 for SCHED_FIFO tasks