[PATCH v2 net-next 01/13] rcu: Add list_next_or_null_rcu
flat view
STALE3123d
From: Tom Herbert <hidden>
Date: 2016-03-07 22:11:49
Subsystem:
read-copy update (rcu), the rest · Maintainers:
"Paul E. McKenney", Frederic Weisbecker, Neeraj Upadhyay, Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki, Linus Torvalds
Revision v2 of 3 in this series.
Revisions (3)
- rfc [diff vs current]
- v1 [diff vs current]
- v2 current
This is a convenience function that returns the next entry in an RCU list or NULL if at the end of the list. Signed-off-by: Tom Herbert <redacted> --- include/linux/rculist.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 14ec165..17d4f84 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h@@ -319,6 +319,27 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, }) /** + * list_next_or_null_rcu - get the first element from a list + * @head: the head for the list. + * @ptr: the list head to take the next 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 ptr is at the end of the list, NULL is returned. + * + * 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_next_or_null_rcu(head, ptr, type, member) \ +({ \ + struct list_head *__head = (head); \ + struct list_head *__ptr = (ptr); \ + struct list_head *__next = READ_ONCE(__ptr->next); \ + likely(__next != __head) ? 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.
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2.6.5