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Commit 83f54960 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ae154be1

kernel/sched_fair.c

+7 −2
Original line number Diff line number Diff line
@@ -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 */