From: Pavel Begunkov <asml.silence@gmail.com>
Date: Fri, 1 May 2020 14:09:37 +0000 (+0300)
Subject: io_uring: check non-sync defer_list carefully
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=4ee3631451c9a62e6b6bc7ee51fb9a5b34e33509;p=linux.git

io_uring: check non-sync defer_list carefully

io_req_defer() do double-checked locking. Use proper helpers for that,
i.e. list_empty_careful().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 7f10af02c3d14..91ddc27b5173c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5031,7 +5031,7 @@ static int io_req_defer(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	int ret;
 
 	/* Still need defer if there is pending req in defer list. */
-	if (!req_need_defer(req) && list_empty(&ctx->defer_list))
+	if (!req_need_defer(req) && list_empty_careful(&ctx->defer_list))
 		return 0;
 
 	if (!req->io && io_alloc_async_ctx(req))