Introduce helpers to atomically switch llist.
Will later move this into common code
Signed-off-by: Dylan Yudaken <dylany@xxxxxx>
---
io_uring/io_uring.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 985b46dfebb6..eb29e3f7da5c 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1009,6 +1009,36 @@ static void handle_tw_list(struct llist_node *node,
} while (node);
}
+/**
+ * io_llist_xchg - swap all entries in a lock-less list
+ * @head: the head of lock-less list to delete all entries
+ * @new: new entry as the head of the list
+ *
+ * If list is empty, return NULL, otherwise, return the pointer to the first entry.
+ * The order of entries returned is from the newest to the oldest added one.
+ */
+static inline struct llist_node *io_llist_xchg(struct llist_head *head,
+ struct llist_node *node)
+{
+ return xchg(&head->first, node);
+}
+
+/**
+ * io_llist_xchg - possibly swap all entries in a lock-less list
+ * @head: the head of lock-less list to delete all entries
+ * @old: expected old value of the first entry of the list
+ * @new: new entry as the head of the list
+ *
+ * perform a cmpxchg on the first entry of the list.
+ */
+
+static inline struct llist_node *io_llist_cmpxchg(struct llist_head *head,
+ struct llist_node *old,
+ struct llist_node *new)
+{
+ return cmpxchg(&head->first, old, new);
+}
+
void tctx_task_work(struct callback_head *cb)
{
bool uring_locked = false;
--
2.30.2
