linux-kernel - [PATCH] Subject: io_uring: Fix bug in io_fallback_req

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Date:   Fri, 12 May 2023 17:56:55 +0800
From:   luhongfei <luhongfei@...o.com>
To:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        io-uring@...r.kernel.org (open list:IO_URING),
        linux-kernel@...r.kernel.org (open list)
Cc:     opensource.kernel@...o.com, luhongfei <luhongfei@...o.com>
Subject: [PATCH] Subject: io_uring: Fix bug in io_fallback_req_func that can cause deadlock

There was a bug in io_fallback_req_func that can cause deadlocks
because uring_lock was not released when return.
This patch releases the uring_lock before return.

Signed-off-by: luhongfei <luhongfei@...o.com>
---
 io_uring/io_uring.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
 mode change 100644 => 100755 io_uring/io_uring.c

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 3bca7a79efda..1af793c7b3da
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -252,8 +252,10 @@ static __cold void io_fallback_req_func(struct work_struct *work)
 	mutex_lock(&ctx->uring_lock);
 	llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
 		req->io_task_work.func(req, &ts);
-	if (WARN_ON_ONCE(!ts.locked))
+	if (WARN_ON_ONCE(!ts.locked)) {
+		mutex_unlock(&ctx->uring_lock);
 		return;
+	}
 	io_submit_flush_completions(ctx);
 	mutex_unlock(&ctx->uring_lock);
 }
-- 
2.39.0