diff options
Diffstat (limited to 'include/linux/rculist.h')
| -rw-r--r-- | include/linux/rculist.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h index e3beb31..52d280b 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -242,6 +242,24 @@ 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 *__next = ACCESS_ONCE(__ptr->next); \ + likely(__ptr != __next) ? \ + list_entry_rcu(__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. |