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From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Cc: [email protected]
Subject: [PATCH 1/2] io_uring: fix __io_uring_files_cancel() with TASK_UNINTERRUPTIBLE
Date: Tue, 26 Jan 2021 15:28:26 +0000	[thread overview]
Message-ID: <565eaac3a631e81bce7094ad6fd5c7a884f53086.1611674535.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

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: [email protected] # 5.9+
Signed-off-by: Pavel Begunkov <[email protected]>
---
 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


  reply	other threads:[~2021-01-26 15:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-26 15:28 [PATCH 5.11 0/2] syzbot fixes Pavel Begunkov
2021-01-26 15:28 ` Pavel Begunkov [this message]
2021-01-26 15:28 ` [PATCH 2/2] io_uring: fix cancellation taking mutex while TASK_UNINTERRUPTIBLE Pavel Begunkov
2021-01-26 15:56   ` Pavel Begunkov
2021-01-26 16:01     ` Jens Axboe
2021-01-26 15:54 ` [PATCH 5.11 0/2] syzbot fixes Jens Axboe

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