Import list_first_entry_or_null() macro from Linux that would be used by Cadence USB driver
Signed-off-by: Vignesh Raghavendra vigneshr@ti.com --- include/linux/list.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/include/linux/list.h b/include/linux/list.h index 5b8d1df5dfee..f62afa092c63 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -348,6 +348,20 @@ static inline void list_splice_tail_init(struct list_head *list, #define list_last_entry(ptr, type, member) \ list_entry((ptr)->prev, type, member)
+/** + * list_first_entry_or_null - 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_head within the struct. + * + * Note that if the list is empty, it returns NULL. + */ +#define list_first_entry_or_null(ptr, type, member) ({ \ + struct list_head *head__ = (ptr); \ + struct list_head *pos__ = READ_ONCE(head__->next); \ + pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ +}) + /** * list_for_each - iterate over a list * @pos: the &struct list_head to use as a loop cursor.