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From: Dylan Yudaken <[email protected]>
To: <[email protected]>, <[email protected]>, <[email protected]>
Cc: <[email protected]>, Dylan Yudaken <[email protected]>
Subject: [PATCH RFC for-next 4/8] io_uring: introduce llist helpers
Date: Mon, 20 Jun 2022 09:18:57 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

Introduce helpers to atomically switch llist.

Will later move this into common code

Signed-off-by: Dylan Yudaken <[email protected]>
---
 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


  parent reply	other threads:[~2022-06-20 16:19 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-20 16:18 [PATCH RFC for-next 0/8] io_uring: tw contention improvments Dylan Yudaken
2022-06-20 16:18 ` [PATCH RFC for-next 1/8] io_uring: remove priority tw list optimisation Dylan Yudaken
2022-06-20 16:18 ` [PATCH RFC for-next 2/8] io_uring: remove __io_req_task_work_add Dylan Yudaken
2022-06-20 16:18 ` [PATCH RFC for-next 3/8] io_uring: lockless task list Dylan Yudaken
2022-06-20 16:18 ` Dylan Yudaken [this message]
2022-06-20 16:18 ` [PATCH RFC for-next 5/8] io_uring: batch task_work Dylan Yudaken
2022-06-20 16:18 ` [PATCH RFC for-next 6/8] io_uring: move io_uring_get_opcode out of TP_printk Dylan Yudaken
2022-06-20 16:19 ` [PATCH RFC for-next 7/8] io_uring: add trace event for running task work Dylan Yudaken
2022-06-20 16:19 ` [PATCH RFC for-next 8/8] io_uring: trace task_work_run Dylan Yudaken
2022-06-21  5:10 ` [PATCH RFC for-next 0/8] io_uring: tw contention improvments Hao Xu
2022-06-21  7:03   ` Dylan Yudaken
2022-06-21  7:34     ` Hao Xu
2022-06-22  9:31       ` Dylan Yudaken
2022-06-22 11:16         ` Hao Xu
2022-06-22 11:24           ` Hao Xu
2022-06-22 11:51             ` Dylan Yudaken
2022-06-22 12:28               ` Hao Xu
2022-06-22 12:29                 ` Hao Xu
2022-06-22 11:52             ` Hao Xu
2022-06-21  7:38     ` Hao Xu

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