cfq-iosched: fix a kernel OOPs when usb key is inserted
[linux-2.6.git] / block / cfq-iosched.c
index f65c6f0..9eba291 100644 (file)
@@ -1019,10 +1019,20 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
         */
        atomic_set(&cfqg->ref, 1);
 
-       /* Add group onto cgroup list */
-       sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
-       cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
+       /*
+        * Add group onto cgroup list. It might happen that bdi->dev is
+        * not initiliazed yet. Initialize this new group without major
+        * and minor info and this info will be filled in once a new thread
+        * comes for IO. See code above.
+        */
+       if (bdi->dev) {
+               sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+               cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
                                        MKDEV(major, minor));
+       } else
+               cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
+                                       0);
+
        cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
 
        /* Add group on cfqd list */