From: "Oliver Giles" <ohw.giles@gmail.com>
To: <linux-kernel@vger.kernel.org>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Christoph Hellwig" <hch@lst.de>
Subject: Splicing to/from a tty
Date: Sat, 16 Jan 2021 20:35:41 +1300 [thread overview]
Message-ID: <C8KER7U60WXE.25UFD8RE6QZQK@oguc> (raw)
Commit 36e2c7421f02 (fs: don't allow splice read/write without explicit ops) broke my userspace application which talks to an SSL VPN by splice()ing between "openssl s_client" and "pppd". The latter operates over a pty, and since that commit there is no fallback for splice()ing between a pipe and a pty, or any tty for that matter.
The above commit mentions switching them to the iter ops and using generic_file_splice_read. IIUC, this would require implementing iter ops also on the line disciplines, which sounds pretty disruptive.
For my case, I attempted to instead implement splice_write and splice_read in tty_fops; I managed to get splice_write working calling ld->ops->write, but splice_read is not so simple because the tty_ldisc_ops read method expects a userspace buffer. So I cannot see how to implement this without either (a) using set_fs, or (b) implementing iter ops on all line disciplines.
Is splice()ing between a tty and a pipe worth supporting at all? Not a big deal for my use case at least, but it used to work.
next reply other threads:[~2021-01-16 8:05 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-16 7:35 Oliver Giles [this message]
2021-01-16 16:46 ` Splicing to/from a tty Johannes Berg
2021-01-17 6:12 ` Oliver Giles
2021-01-18 8:53 ` Christoph Hellwig
2021-01-18 8:58 ` Johannes Berg
2021-01-18 19:26 ` Linus Torvalds
2021-01-18 19:45 ` Al Viro
2021-01-18 19:49 ` Linus Torvalds
2021-01-18 19:56 ` Al Viro
2021-01-24 19:11 ` Linus Torvalds
2021-01-25 9:16 ` [PATCH] fs/pipe: allow sendfile() to pipe again Johannes Berg
2021-01-25 10:16 ` Christoph Hellwig
2021-01-25 20:34 ` Linus Torvalds
2021-01-26 6:07 ` Splicing to/from a tty Al Viro
2021-01-26 6:08 ` [PATCH 1/3] do_splice_to(): move the logics for limiting the read length in Al Viro
2021-01-26 6:09 ` [PATCH 2/3] take the guts of file-to-pipe splice into a helper function Al Viro
2021-01-26 6:09 ` [PATCH 3/3] teach sendfile(2) to handle send-to-pipe directly Al Viro
2021-01-26 18:57 ` Linus Torvalds
2021-01-26 19:33 ` Al Viro
2021-01-26 18:49 ` Splicing to/from a tty Linus Torvalds
2021-01-26 19:42 ` Al Viro
2021-01-18 19:34 ` Al Viro
2021-01-18 19:46 ` Linus Torvalds
2021-01-18 19:54 ` Al Viro
2021-01-20 16:26 ` Al Viro
2021-01-20 19:11 ` Al Viro
2021-01-20 19:27 ` Linus Torvalds
2021-01-20 22:25 ` David Laight
2021-01-20 23:02 ` Al Viro
2021-01-20 23:14 ` Al Viro
2021-01-20 23:40 ` Linus Torvalds
2021-01-21 0:38 ` Al Viro
2021-01-21 1:04 ` Linus Torvalds
2021-01-21 1:45 ` Al Viro
2021-01-21 3:38 ` Linus Torvalds
2021-01-21 6:05 ` Willy Tarreau
2021-01-21 8:04 ` Johannes Berg
2021-01-21 10:08 ` David Laight
2021-01-18 8:16 ` Christoph Hellwig
2021-01-18 19:36 ` Linus Torvalds
2021-01-18 20:24 ` Linus Torvalds
2021-01-18 21:35 ` Linus Torvalds
2021-01-18 21:54 ` Linus Torvalds
2021-01-18 22:03 ` Linus Torvalds
2021-01-18 22:20 ` Linus Torvalds
2021-01-19 1:38 ` Linus Torvalds
2021-01-19 11:53 ` Greg Kroah-Hartman
2021-01-19 16:56 ` Robert Karszniewicz
2021-01-19 17:10 ` Robert Karszniewicz
2021-01-19 22:09 ` Oliver Giles
2021-01-19 17:25 ` Linus Torvalds
2021-01-19 20:24 ` Linus Torvalds
2021-01-19 20:38 ` Christoph Hellwig
2021-01-20 1:25 ` Oliver Giles
2021-01-20 4:44 ` Linus Torvalds
2021-01-20 8:15 ` Oliver Giles
2021-01-21 1:18 ` tty splice branch (was "Re: Splicing to/from a tty") Linus Torvalds
2021-01-21 8:44 ` Greg Kroah-Hartman
2021-01-21 8:50 ` Jiri Slaby
2021-01-21 8:58 ` Jiri Slaby
2021-01-21 17:52 ` Linus Torvalds
2021-01-21 8:58 ` Greg Kroah-Hartman
2021-01-21 17:03 ` Splicing to/from a tty Robert Karszniewicz
2021-01-21 18:43 ` Linus Torvalds
2021-01-19 11:52 ` Greg Kroah-Hartman
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