cfq-iosched: fix use-after-free of cfqq

[~andy/linux] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 163263ddd3814e3f087eb1a7e1461242fabbd702..ee55019066a19500c6df54addf90d91d2ace60fa 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3117,18 +3117,17 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
  */
 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-       struct cfq_queue *old_cfqq = cfqd->active_queue;
-
        cfq_log_cfqq(cfqd, cfqq, "preempt");
-       cfq_slice_expired(cfqd, 1);
 
        /*
         * workload type is changed, don't save slice, otherwise preempt
         * doesn't happen
         */
-       if (cfqq_type(old_cfqq) != cfqq_type(cfqq))
+       if (cfqq_type(cfqd->active_queue) != cfqq_type(cfqq))
                cfqq->cfqg->saved_workload_slice = 0;
 
+       cfq_slice_expired(cfqd, 1);
+
        /*
         * Put the new queue at the front of the of the current list,
         * so we know that it will be selected next.