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sched: for_each_domain() vs RCU 

for_each_domain() uses RCU to serialize the sched_domains, except
it doesn't actually use rcu_read_lock() and instead relies on
disabling preemption -> FAIL.

XXX: audit other sched_domain code.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-09-10 18:18:47 +02:00 committed by Ingo Molnar
parent ae154be1f3
commit 83f54960c1
1 changed files with 7 additions and 2 deletions
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9
kernel/sched_fair.c
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@ -1331,6 +1331,7 @@ static int select_task_rq_fair(struct task_struct *p, int flag, int sync)
new_cpu = prev_cpu;
}
rcu_read_lock();
for_each_domain(cpu, tmp) {
/*
* If power savings logic is enabled for a domain, see if we
@ -1369,8 +1370,10 @@ static int select_task_rq_fair(struct task_struct *p, int flag, int sync)
if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
if (wake_affine(tmp, p, sync))
return cpu;
if (wake_affine(tmp, p, sync)) {
new_cpu = cpu;
goto out;
}
want_affine = 0;
}
@ -1416,6 +1419,8 @@ static int select_task_rq_fair(struct task_struct *p, int flag, int sync)
/* while loop will break here if sd == NULL */
}
out:
rcu_read_unlock();
return new_cpu;
}
#endif /* CONFIG_SMP */