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authorHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>2007-09-19 23:34:46 +0200
committerIngo Molnar <mingo@elte.hu>2007-09-19 23:34:46 +0200
commit9c95e7319ba98585ebb6d304eca2d56f401ed70c (patch)
treeb650a409da9c1e1feb289cfb16ce2fa05c602216
parent1799e35d5baab6e06168b46cc78b968e728ea3d1 (diff)
downloadlinux-stericsson-9c95e7319ba98585ebb6d304eca2d56f401ed70c.tar.gz
sched: fix invalid sched_class use
When using rt_mutex, a NULL pointer dereference is occurred at enqueue_task_rt. Here is a scenario; 1) there are two threads, the thread A is fair_sched_class and thread B is rt_sched_class. 2) Thread A is boosted up to rt_sched_class, because the thread A has a rt_mutex lock and the thread B is waiting the lock. 3) At this time, when thread A create a new thread C, the thread C has a rt_sched_class. 4) When doing wake_up_new_task() for the thread C, the priority of the thread C is out of the RT priority range, because the normal priority of thread A is not the RT priority. It makes data corruption by overflowing the rt_prio_array. The new thread C should be fair_sched_class. The new thread should be valid scheduler class before queuing. This patch fixes to set the suitable scheduler class. Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
-rw-r--r--kernel/sched.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 63e0971c8fbb..6107a0cd6325 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1682,6 +1682,11 @@ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
p->prio = effective_prio(p);
+ if (rt_prio(p->prio))
+ p->sched_class = &rt_sched_class;
+ else
+ p->sched_class = &fair_sched_class;
+
if (!p->sched_class->task_new || !sysctl_sched_child_runs_first ||
(clone_flags & CLONE_VM) || task_cpu(p) != this_cpu ||
!current->se.on_rq) {