3 files changed, 21 insertions, 7 deletions

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index f025fd1e22e6..76c61318fda5 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -499,22 +499,33 @@ static inline void blkg_get(struct blkcg_gq *blkg)
  */
 static inline bool blkg_tryget(struct blkcg_gq *blkg)
 {
-        return percpu_ref_tryget(&blkg->refcnt);
+        return blkg && percpu_ref_tryget(&blkg->refcnt);
 }
 
 /**
  * blkg_tryget_closest - try and get a blkg ref on the closet blkg
  * @blkg: blkg to get
  *
- * This walks up the blkg tree to find the closest non-dying blkg and returns
- * the blkg that it did association with as it may not be the passed in blkg.
+ * This needs to be called rcu protected.  As the failure mode here is to walk
+ * up the blkg tree, this ensure that the blkg->parent pointers are always
+ * valid.  This returns the blkg that it ended up taking a reference on or %NULL
+ * if no reference was taken.
  */
 static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
 {
-        while (blkg && !percpu_ref_tryget(&blkg->refcnt))
+        struct blkcg_gq *ret_blkg = NULL;
+
+        WARN_ON_ONCE(!rcu_read_lock_held());
+
+        while (blkg) {
+                if (blkg_tryget(blkg)) {
+                        ret_blkg = blkg;
+                        break;
+                }
                 blkg = blkg->parent;
+        }
 
-        return blkg;
+        return ret_blkg;
 }
 
 /**
diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 2d0259327721..a19d98367f08 100644
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -51,7 +51,7 @@
 #endif
 
 extern const char *drbd_buildtag(void);
-#define REL_VERSION "8.4.10"
+#define REL_VERSION "8.4.11"
 #define API_VERSION 1
 #define PRO_VERSION_MIN 86
 #define PRO_VERSION_MAX 101
diff --git a/include/linux/genl_magic_struct.h b/include/linux/genl_magic_struct.h
index 5972e4969197..eeae59d3ceb7 100644
--- a/include/linux/genl_magic_struct.h
+++ b/include/linux/genl_magic_struct.h
@@ -191,6 +191,7 @@ static inline void ct_assert_unique_operations(void)
 {
         switch (0) {
 #include GENL_MAGIC_INCLUDE_FILE
+        case 0:
                 ;
         }
 }
@@ -209,6 +210,7 @@ static inline void ct_assert_unique_top_level_attributes(void)
 {
         switch (0) {
 #include GENL_MAGIC_INCLUDE_FILE
+        case 0:
                 ;
         }
 }
@@ -218,7 +220,8 @@ static inline void ct_assert_unique_top_level_attributes(void)
 static inline void ct_assert_unique_ ## s_name ## _attributes(void)     \
 {                                                                       \
         switch (0) {                                                    \
-                s_fields                                                \
+        s_fields                                                        \
+        case 0:                                                         \
                         ;                                               \
         }                                                               \
 }