cfq-iosched: fix locking around ioc->ioc_data assignment
[linux-2.6.git] / block / cfq-iosched.c
index a2fb14b..000719c 100644 (file)
@@ -2767,8 +2767,11 @@ static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
        smp_wmb();
        cic->key = cfqd_dead_key(cfqd);
 
-       if (ioc->ioc_data == cic)
+       if (rcu_dereference(ioc->ioc_data) == cic) {
+               spin_lock(&ioc->lock);
                rcu_assign_pointer(ioc->ioc_data, NULL);
+               spin_unlock(&ioc->lock);
+       }
 
        if (cic->cfqq[BLK_RW_ASYNC]) {
                cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);