diff options
| author | Vignesh Raghavendra <vigneshr@ti.com> | 2019-10-01 17:26:29 +0530 |
|---|---|---|
| committer | Marek Vasut <marek.vasut+renesas@gmail.com> | 2019-11-07 00:24:59 +0100 |
| commit | c37f594280aa3fc9d534420581f7db47ac843297 (patch) | |
| tree | 4f4c1afaed1af5a4e2d473e3296931c2bd61b869 /include/linux | |
| parent | 0f282c1876af26cc2c8c018ae6293a691561011e (diff) | |
list: import list_first_entry_or_null()
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>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/list.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/list.h b/include/linux/list.h index 5b8d1df5df..f62afa092c 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -349,6 +349,20 @@ static inline void list_splice_tail_init(struct list_head *list, 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. * @head: the head for your list. |