cfq-iosched: fix RCU race in the cfq io_context destructor handling

[linux-2.6-omap-h63xx.git] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index f4e1006c253d3ade81cc9b39ce80da6612b277a6..7f909d2f4886d36aaea83836a07a9d255d3e7de5 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1142,6 +1142,17 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
        kmem_cache_free(cfq_pool, cfqq);
 }
 
+static void
+__call_for_each_cic(struct io_context *ioc,
+                   void (*func)(struct io_context *, struct cfq_io_context *))
+{
+       struct cfq_io_context *cic;
+       struct hlist_node *n;
+
+       hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
+               func(ioc, cic);
+}
+
 /*
  * Call func for each cic attached to this ioc.
  */
@@ -1149,12 +1160,8 @@ static void
 call_for_each_cic(struct io_context *ioc,
                  void (*func)(struct io_context *, struct cfq_io_context *))
 {
-       struct cfq_io_context *cic;
-       struct hlist_node *n;
-
        rcu_read_lock();
-       hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
-               func(ioc, cic);
+       __call_for_each_cic(ioc, func);
        rcu_read_unlock();
 }
 
@@ -1198,7 +1205,7 @@ static void cfq_free_io_context(struct io_context *ioc)
         * should be ok to iterate over the known list, we will see all cic's
         * since no new ones are added.
         */
-       call_for_each_cic(ioc, cic_free_func);
+       __call_for_each_cic(ioc, cic_free_func);
 }
 
 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)