[PATCH 2/3] io_uring: check non-sync defer_list carefully

From: Pavel Begunkov
Date: Fri May 01 2020 - 10:10:58 EST


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

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

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e7d7e83e3d56..e5d560f2ce12 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5028,7 +5028,7 @@ 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))
--
2.24.0