[tip: locking/core] io_uring: use __xchg if possible

[tip-bot2 for Andrzej Hajda]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     bd1e2670ebd10ad727b92ddd424cca270314f5ee
Gitweb:        https://git.kernel.org/tip/bd1e2670ebd10ad727b92ddd424cca270314f5ee
Author:        Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
AuthorDate:    Wed, 18 Jan 2023 16:44:48 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Sat, 11 Mar 2023 14:03:59 +01:00

io_uring: use __xchg if possible

Recently introduced helper simplifies the code.

Signed-off-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230118154450.73842-5-andrzej.hajda@xxxxxxxxx
---
 io_uring/io_uring.c | 7 ++-----
 io_uring/slist.h    | 6 ++----
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index fd1cc35..0cd89a3 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -54,6 +54,7 @@
 #include <linux/fdtable.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
+#include <linux/non-atomic/xchg.h>
 #include <linux/percpu.h>
 #include <linux/slab.h>
 #include <linux/bvec.h>
@@ -1131,8 +1132,6 @@ static void __io_req_find_next_prep(struct io_kiocb *req)
 
 static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
 {
-	struct io_kiocb *nxt;
-
 	/*
 	 * If LINK is set, we have dependent requests in this chain. If we
 	 * didn't fail this request, queue the first one up, moving any other
@@ -1141,9 +1140,7 @@ static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
 	 */
 	if (unlikely(req->flags & IO_DISARM_MASK))
 		__io_req_find_next_prep(req);
-	nxt = req->link;
-	req->link = NULL;
-	return nxt;
+	return __xchg(&req->link, NULL);
 }
 
 static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked)
diff --git a/io_uring/slist.h b/io_uring/slist.h
index 7c198a4..051e577 100644
--- a/io_uring/slist.h
+++ b/io_uring/slist.h
@@ -2,6 +2,7 @@
 #define INTERNAL_IO_SLIST_H
 
 #include <linux/io_uring_types.h>
+#include <linux/non-atomic/xchg.h>
 
 #define wq_list_for_each(pos, prv, head)			\
 	for (pos = (head)->first, prv = NULL; pos; prv = pos, pos = (pos)->next)
@@ -99,10 +100,7 @@ static inline void wq_list_del(struct io_wq_work_list *list,
 static inline
 struct io_wq_work_node *wq_stack_extract(struct io_wq_work_node *stack)
 {
-	struct io_wq_work_node *node = stack->next;
-
-	stack->next = node->next;
-	return node;
+	return __xchg(&stack->next, stack->next->next);
 }
 
 static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)