[PATCH 5.10 09/54] io_uring: fix __io_uring_files_cancel() with TASK_UNINTERRUPTIBLE

Greg Kroah-Hartman
2021-02-11T15:44:02Z

From: Pavel Begunkov <asml.silence@gmail.com>

[ Upstream commit a1bb3cd58913338e1b627ea6b8c03c2ae82d293f ]

If the tctx inflight number haven't changed because of cancellation,
__io_uring_task_cancel() will continue leaving the task in
TASK_UNINTERRUPTIBLE state, that's not expected by
__io_uring_files_cancel(). Ensure we always call finish_wait() before
retrying.

Cc: stable@vger.kernel.org # 5.9+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/io_uring.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8829,15 +8829,15 @@ void __io_uring_task_cancel(void)
prepare_to_wait(&tctx->wait, &wait, TASK_UNINTERRUPTIBLE);

/*
- * If we've seen completions, retry. This avoids a race where
- * a completion comes in before we did prepare_to_wait().
+ * If we've seen completions, retry without waiting. This
+ * avoids a race where a completion comes in before we did
+ * prepare_to_wait().
*/
- if (inflight != tctx_inflight(tctx))
- continue;
- schedule();
+ if (inflight == tctx_inflight(tctx))
+ schedule();
+ finish_wait(&tctx->wait, &wait);
} while (1);

- finish_wait(&tctx->wait, &wait);
atomic_dec(&tctx->in_idle);

io_uring_remove_task_files(tctx);