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Commit adac1665 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[PATCH] rcu_torture_lock deadlock fix 



rcu_torture_lock is used in a softirq-unsafe manner, but it is also
taken by rcu_torture_cb(), which may execute in softirq-context,
resulting in potential deadlocks.

The fix is to acquire rcu_torture_lock in a softirq-safe manner.  With
this fix applied, the rcu-torture code passes validation.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarPaul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f6bc2666

kernel/rcutorture.c

+5 −5
Original line number Diff line number Diff line
@@ -114,16 +114,16 @@ rcu_torture_alloc(void) 
{

	struct list_head *p;



	spin_lock(&rcu_torture_lock);

	spin_lock_bh(&rcu_torture_lock);

	if (list_empty(&rcu_torture_freelist)) {

		atomic_inc(&n_rcu_torture_alloc_fail);

		spin_unlock(&rcu_torture_lock);

		spin_unlock_bh(&rcu_torture_lock);

		return NULL;

	}

	atomic_inc(&n_rcu_torture_alloc);

	p = rcu_torture_freelist.next;

	list_del_init(p);

	spin_unlock(&rcu_torture_lock);

	spin_unlock_bh(&rcu_torture_lock);

	return container_of(p, struct rcu_torture, rtort_free);

}
@@ -134,9 +134,9 @@ static void 
rcu_torture_free(struct rcu_torture *p)

{

	atomic_inc(&n_rcu_torture_free);

	spin_lock(&rcu_torture_lock);

	spin_lock_bh(&rcu_torture_lock);

	list_add_tail(&p->rtort_free, &rcu_torture_freelist);

	spin_unlock(&rcu_torture_lock);

	spin_unlock_bh(&rcu_torture_lock);

}



static void