[PATCH 2/2] io_uring: replace cmpxchg in fallback with xchg

[Pavel Begunkov <asml.silence@xxxxxxxxx>]

io_run_ctx_fallback() can use xchg() instead of cmpxchg(). It's faster
and faster.

Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
---
 fs/io_uring.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 365e75b53a78..42b675939582 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8489,15 +8489,11 @@ static int io_remove_personalities(int id, void *p, void *data)
 
 static bool io_run_ctx_fallback(struct io_ring_ctx *ctx)
 {
-	struct callback_head *work, *head, *next;
+	struct callback_head *work, *next;
 	bool executed = false;
 
 	do {
-		do {
-			head = NULL;
-			work = READ_ONCE(ctx->exit_task_work);
-		} while (cmpxchg(&ctx->exit_task_work, work, head) != work);
-
+		work = xchg(&ctx->exit_task_work, NULL);
 		if (!work)
 			break;
 
-- 
2.24.0