From: Ingo Molnar <mingo@elte.hu>
Rusty noticed that we update the parent ->avg_sleep without holding the
runqueue lock. Also the code needed cleanups.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/kernel/sched.c | 24 +++++++++++++++---------
1 files changed, 15 insertions(+), 9 deletions(-)
diff -puN kernel/sched.c~sched-new-task-fix kernel/sched.c
--- 25/kernel/sched.c~sched-new-task-fix Tue Aug 17 15:03:25 2004
+++ 25-akpm/kernel/sched.c Tue Aug 17 15:03:25 2004
@@ -1342,7 +1342,7 @@ void fastcall wake_up_new_task(task_t *
{
unsigned long flags;
int this_cpu, cpu;
- runqueue_t *rq;
+ runqueue_t *rq, *this_rq;
rq = task_rq_lock(p, &flags);
cpu = task_cpu(p);
@@ -1384,8 +1384,15 @@ void fastcall wake_up_new_task(task_t *
} else
/* Run child last */
__activate_task(p, rq);
+ /*
+ * We skip the following code due to cpu == this_cpu
+ *
+ * task_rq_unlock(rq, &flags);
+ * this_rq = task_rq_lock(current, &flags);
+ */
+ this_rq = rq;
} else {
- runqueue_t *this_rq = cpu_rq(this_cpu);
+ this_rq = cpu_rq(this_cpu);
/*
* Not the local CPU - must adjust timestamp. This should
@@ -1397,18 +1404,17 @@ void fastcall wake_up_new_task(task_t *
if (TASK_PREEMPTS_CURR(p, rq))
resched_task(rq->curr);
- current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
- PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
schedstat_inc(rq, wunt_moved);
- }
-
- if (unlikely(cpu != this_cpu)) {
+ /*
+ * Parent and child are on different CPUs, now get the
+ * parent runqueue to update the parent's ->sleep_avg:
+ */
task_rq_unlock(rq, &flags);
- rq = task_rq_lock(current, &flags);
+ this_rq = task_rq_lock(current, &flags);
}
current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) *
PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
- task_rq_unlock(rq, &flags);
+ task_rq_unlock(this_rq, &flags);
}
/*
_