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Message-Id: <20210712061049.765644537@linuxfoundation.org>
Date: Mon, 12 Jul 2021 08:12:57 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Birk Hirdman <lonjil@...il.com>,
Pavel Begunkov <asml.silence@...il.com>,
Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.12 694/700] io_uring: fix blocking inline submission
From: Pavel Begunkov <asml.silence@...il.com>
commit 976517f162a05f4315b2373fd11585c395506259 upstream.
There is a complaint against sys_io_uring_enter() blocking if it submits
stdin reads. The problem is in __io_file_supports_async(), which
sees that it's a cdev and allows it to be processed inline.
Punt char devices using generic rules of io_file_supports_async(),
including checking for presence of *_iter() versions of rw callbacks.
Apparently, it will affect most of cdevs with some exceptions like
null and zero devices.
Cc: stable@...r.kernel.org
Reported-by: Birk Hirdman <lonjil@...il.com>
Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
Link: https://lore.kernel.org/r/d60270856b8a4560a639ef5f76e55eb563633599.1623236455.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
fs/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2683,7 +2683,7 @@ static bool io_file_supports_async(struc
return true;
return false;
}
- if (S_ISCHR(mode) || S_ISSOCK(mode))
+ if (S_ISSOCK(mode))
return true;
if (S_ISREG(mode)) {
if (IS_ENABLED(CONFIG_BLOCK) &&
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