[PATCH 4/4] io_uring: cancel requests enqueued as task_work's

From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org
Cc: stable@vger.kernel.org
Subject: [PATCH 4/4] io_uring: cancel requests enqueued as task_work's
Date: Wed, 30 Dec 2020 21:34:17 +0000	[thread overview]
Message-ID: <9d7a1c5ce3fe2a6054382760b9ef68f03c6e11ba.1609361865.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1609361865.git.asml.silence@gmail.com>

Currently request cancellations are happening before PF_EXITING is set,
so it's allowed to call task_work_run(). Even though it should work as
it's not it's safer to remove PF_EXITING checks.

Cc: stable@vger.kernel.org # 5.5+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 fs/io_uring.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ca46f314640b..8d4fa0031e0a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2361,12 +2361,8 @@ static inline unsigned int io_put_rw_kbuf(struct io_kiocb *req)
 
 static inline bool io_run_task_work(void)
 {
-	/*
-	 * Not safe to run on exiting task, and the task_work handling will
-	 * not add work to such a task.
-	 */
-	if (unlikely(current->flags & PF_EXITING))
-		return false;
+	WARN_ON_ONCE(current->flags & PF_EXITING);
+
 	if (current->task_works) {
 		__set_current_state(TASK_RUNNING);
 		task_work_run();
-- 
2.24.0

