Received-SPF: pass (google.com: domain of linux-kernel+bounces-7782-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Date: Thu, 21 Dec 2023 04:09:10 +0100
From: 
	Ahelenia =?utf-8?Q?Ziemia=C5=84ska?= <nabijaczleweli@nabijaczleweli.xyz>
Cc: Jens Axboe <axboe@kernel.dk>, Christian Brauner <brauner@kernel.org>, 
	Alexander Viro <viro@zeniv.linux.org.uk>, linux-fsdevel@vger.kernel.org, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jirislaby@kernel.org>, linux-kernel@vger.kernel.org, 
	linux-serial@vger.kernel.org
Subject: [PATCH v2 08/11] tty: splice_read: disable
Message-ID: <4dec932dcd027aa5836d70a6d6bedd55914c84c2.1703126594.git.nabijaczleweli@nabijaczleweli.xyz>
References: <cover.1703126594.git.nabijaczleweli@nabijaczleweli.xyz>
Precedence: bulk
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="xhoon5hag52ewyt5"
Content-Disposition: inline
In-Reply-To: <cover.1703126594.git.nabijaczleweli@nabijaczleweli.xyz>
User-Agent: NeoMutt/20231103-116-3b855e-dirty


--xhoon5hag52ewyt5
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

We request non-blocking I/O in the generic copy_splice_read, but
"the tty layer doesn't actually honor the IOCB_NOWAIT flag for
various historical reasons.". This means that a tty->pipe splice
will happily sleep with the pipe locked forever, and any process
trying to take it (due to an open/read/write/&c.) will enter
uninterruptible sleep.

This also masks inconsistent wake-ups (usually every second line)
when splicing from ttys in icanon mode.

Link: https://lore.kernel.org/linux-fsdevel/CAHk-=3DwimmqG_wvSRtMiKPeGGDL81=
6n65u=3DMq2+H3-=3DuM2U6FmA@mail.gmail.com/
Signed-off-by: Ahelenia Ziemia=C5=84ska <nabijaczleweli@nabijaczleweli.xyz>
---
 drivers/tty/tty_io.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 06414e43e0b5..50c2957a9c7f 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -465,7 +465,6 @@ static const struct file_operations tty_fops =3D {
 	.llseek		=3D no_llseek,
 	.read_iter	=3D tty_read,
 	.write_iter	=3D tty_write,
-	.splice_read	=3D copy_splice_read,
 	.splice_write	=3D iter_file_splice_write,
 	.poll		=3D tty_poll,
 	.unlocked_ioctl	=3D tty_ioctl,
@@ -480,7 +479,6 @@ static const struct file_operations console_fops =3D {
 	.llseek		=3D no_llseek,
 	.read_iter	=3D tty_read,
 	.write_iter	=3D redirected_tty_write,
-	.splice_read	=3D copy_splice_read,
 	.splice_write	=3D iter_file_splice_write,
 	.poll		=3D tty_poll,
 	.unlocked_ioctl	=3D tty_ioctl,
--=20
2.39.2

--xhoon5hag52ewyt5
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=e2Gy
-----END PGP SIGNATURE-----

--xhoon5hag52ewyt5--