diff options
Diffstat (limited to 'include/linux/list.h')
| -rw-r--r-- | include/linux/list.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/list.h b/include/linux/list.h index 00ea8e5fb88b..09d979976b3b 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -191,6 +191,29 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head) __list_add(new, head->prev, head); } +/** + * list_add_tail_release - add a new entry with release barrier + * @new: new entry to be added + * @head: list head to add it before + * + * Insert a new entry before the specified head, using a release barrier to set + * the ->next pointer that points to it. This is useful for implementing + * queues, in particular one that the elements will be walked through forwards + * locklessly. + */ +static inline void list_add_tail_release(struct list_head *new, + struct list_head *head) +{ + struct list_head *prev = head->prev; + + if (__list_add_valid(new, prev, head)) { + new->next = head; + new->prev = prev; + head->prev = new; + smp_store_release(&prev->next, new); + } +} + /* * Delete a list entry by making the prev/next entries * point to each other. @@ -645,6 +668,20 @@ static inline void list_splice_tail_init(struct list_head *list, }) /** + * list_first_entry_or_null_acquire - get the first element from a list with barrier + * @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_head within the struct. + * + * Note that if the list is empty, it returns NULL. + */ +#define list_first_entry_or_null_acquire(ptr, type, member) ({ \ + struct list_head *head__ = (ptr); \ + struct list_head *pos__ = smp_load_acquire(&head__->next); \ + pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ +}) + +/** * list_last_entry_or_null - get the last element from a list * @ptr: the list head to take the element from. * @type: the type of the struct this is embedded in. |