From a1bb3cd58913338e1b627ea6b8c03c2ae82d293f Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Tue, 26 Jan 2021 15:28:26 +0000
Subject: [PATCH] io_uring: fix __io_uring_files_cancel() with
 TASK_UNINTERRUPTIBLE

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>
---
 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 2166c469789d5..09aada153a71b 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);
-- 
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