linux-kernel - [PATCH 2/3] io_uring: check non-sync defer

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Message-Id: <c3224e56c1d1f97cf40e8dc1e03723b0dc4137cf.1588341674.git.asml.silence@gmail.com>
Date:   Fri,  1 May 2020 17:09:37 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] 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@...il.com>
---
 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