X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=block%2Fblk-cgroup.c;h=d0b770391ad400ad0312049c84a2b522bf985bf1;hb=f5f165418cabf2218eb466c0e94693b8b1aee88b;hp=cafcd743118969daec377f52f09e41594d188347;hpb=068a565afad3ae818cc0d5495479c4abccc7762c;p=pandora-kernel.git

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index cafcd7431189..d0b770391ad4 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -285,6 +285,13 @@ static void blkg_destroy_all(struct request_queue *q)
 		blkg_destroy(blkg);
 		spin_unlock(&blkcg->lock);
 	}
+
+	/*
+	 * root blkg is destroyed.  Just clear the pointer since
+	 * root_rl does not take reference on root blkg.
+	 */
+	q->root_blkg = NULL;
+	q->root_rl.blkg = NULL;
 }
 
 static void blkg_rcu_free(struct rcu_head *rcu_head)
@@ -326,6 +333,9 @@ struct request_list *__blk_queue_next_rl(struct request_list *rl,
 	 */
 	if (rl == &q->root_rl) {
 		ent = &q->blkg_list;
+		/* There are no more block groups, hence no request lists */
+		if (list_empty(ent))
+			return NULL;
 	} else {
 		blkg = container_of(rl, struct blkcg_gq, rl);
 		ent = &blkg->q_node;