aboutsummaryrefslogtreecommitdiffstats
path: root/include
diff options
context:
space:
mode:
Diffstat (limited to 'include')
-rw-r--r--include/linux/rculist.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index e3beb31..c30ffd8 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -242,6 +242,23 @@ static inline void list_splice_init_rcu(struct list_head *list,
list_entry_rcu((ptr)->next, type, member)
/**
+ * list_first_or_null_rcu - get the first element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_struct within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
+ */
+#define list_first_or_null_rcu(ptr, type, member) \
+ ({struct list_head *__ptr = (ptr); \
+ struct list_head __rcu *__next = list_next_rcu(__ptr); \
+ likely(__ptr != __next) ? container_of(__next, type, member) : NULL; \
+ })
+
+/**
* list_for_each_entry_rcu - iterate over rcu list of given type
* @pos: the type * to use as a loop cursor.
* @head: the head for your list.