2 files changed, 9 insertions, 15 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 069bc202ffe3..1463ca6b7aae 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -80,7 +80,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
         blkg->q = q;
         INIT_LIST_HEAD(&blkg->q_node);
         blkg->blkcg = blkcg;
-        blkg->refcnt = 1;
+        atomic_set(&blkg->refcnt, 1);
 
         /* root blkg uses @q->root_rl, init rl only for !root blkgs */
         if (blkcg != &blkcg_root) {
@@ -399,11 +399,8 @@ void __blkg_release_rcu(struct rcu_head *rcu_head)
 
         /* release the blkcg and parent blkg refs this blkg has been holding */
         css_put(&blkg->blkcg->css);
-        if (blkg->parent) {
-                spin_lock_irq(blkg->q->queue_lock);
+        if (blkg->parent)
                 blkg_put(blkg->parent);
-                spin_unlock_irq(blkg->q->queue_lock);
-        }
 
         blkg_free(blkg);
 }
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index cbb7f943f78a..1c401b057151 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -18,6 +18,7 @@
 #include <linux/seq_file.h>
 #include <linux/radix-tree.h>
 #include <linux/blkdev.h>
+#include <linux/atomic.h>
 
 /* Max limits for throttle policy */
 #define THROTL_IOPS_MAX         UINT_MAX
@@ -104,7 +105,7 @@ struct blkcg_gq {
         struct request_list             rl;
 
         /* reference count */
-        int                             refcnt;
+        atomic_t                        refcnt;
 
         /* is this blkg online? protected by both blkcg and q locks */
         bool                            online;
@@ -257,13 +258,12 @@ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
  * blkg_get - get a blkg reference
  * @blkg: blkg to get
  *
- * The caller should be holding queue_lock and an existing reference.
+ * The caller should be holding an existing reference.
  */
 static inline void blkg_get(struct blkcg_gq *blkg)
 {
-        lockdep_assert_held(blkg->q->queue_lock);
-        WARN_ON_ONCE(!blkg->refcnt);
-        blkg->refcnt++;
+        WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
+        atomic_inc(&blkg->refcnt);
 }
 
 void __blkg_release_rcu(struct rcu_head *rcu);
@@ -271,14 +271,11 @@ void __blkg_release_rcu(struct rcu_head *rcu);
 /**
  * blkg_put - put a blkg reference
  * @blkg: blkg to put
- *
- * The caller should be holding queue_lock.
  */
 static inline void blkg_put(struct blkcg_gq *blkg)
 {
-        lockdep_assert_held(blkg->q->queue_lock);
-        WARN_ON_ONCE(blkg->refcnt <= 0);
-        if (!--blkg->refcnt)
+        WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
+        if (atomic_dec_and_test(&blkg->refcnt))
                 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 }