From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Richard Weinberger <richard@nod.at>, Jiri Slaby <jslaby@suse.cz>,
linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org,
Jiri Slaby <jirislaby@gmail.com>
Subject: Re: TTY: tty_port questions
Date: Sun, 25 Mar 2012 22:09:07 +0100 [thread overview]
Message-ID: <20120325220907.0591f517@ultron> (raw)
In-Reply-To: <20120325172018.GL6589@ZenIV.linux.org.uk>
On Sun, 25 Mar 2012 18:20:18 +0100
Al Viro <viro@ZenIV.linux.org.uk> wrote:
> On Sun, Mar 25, 2012 at 05:14:37PM +0200, Richard Weinberger wrote:
> > >> FWIW, uml console in default config is basically "start xterm for each VC".
> > >> What do you suggest to do on vhangup() on one of those?
> > >
> > > What posix says must happen. Which is that the running processes get a
> > > hangup. So a vhangup() would ensure there were no old apps on the UML
> > > guess talking to the xterm (eg stealing login credentials, or abusing
> > > TIOCSTI etc).
>
> IIRC, vhangup(2) is Linux-specific, so I would be surprised if POSIX had
> anything on it...
vhangup causes a carrier drop event equivalent. The rest of the behavior
is POSIX/SUSv3.
> login(1) from util-linux does vhangup(); login(1) from shadow doesn't.
Shadow assumes the getty cleans the channel I believe.
> The thing is, we don't want to do that when port is in use. And we definitely
> don't want somebody to open the damn thing when it's halfway through getting
> set up. I don't see any natural way to do that exclusion with tty_port -
> port->{count,block_open} is protected only by a spinlock and port setup
> we need to do is blocking...
How does this differ from a hardware hotplug ?
Alan
next prev parent reply other threads:[~2012-03-25 21:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-10 22:26 TTY: tty_port questions Richard Weinberger
2012-03-10 22:51 ` Jiri Slaby
2012-03-10 23:21 ` Richard Weinberger
2012-03-11 11:01 ` Richard Weinberger
2012-03-12 10:26 ` Richard Weinberger
2012-03-12 10:53 ` Alan Cox
2012-03-12 11:15 ` Richard Weinberger
2012-03-12 11:48 ` Alan Cox
2012-03-24 23:20 ` Al Viro
2012-03-25 14:51 ` Alan Cox
2012-03-25 15:14 ` Richard Weinberger
2012-03-25 17:20 ` Al Viro
2012-03-25 21:09 ` Alan Cox [this message]
2012-03-25 18:31 ` Al Viro
2012-03-25 21:06 ` Alan Cox
2012-03-25 22:33 ` Al Viro
2012-03-28 11:06 ` Alan Cox
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