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>
This commit is contained in:
Pavel Begunkov 2020-05-01 17:09:37 +03:00 committed by Jens Axboe
parent 7759a0bfad
commit 4ee3631451

View file

@ -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))