[PATCH 1/2] io_uring: fix __io_uring_files_cancel() with TASK_UNINTERRUPTIBLE

Pavel Begunkov
2021-01-26T15:33:15Z

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>
---
fs/io_uring.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2166c469789d..09aada153a71 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9124,16 +9124,15 @@ 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);
--
2.24.0