From: "H. Peter Anvin" <hpa@zytor.com>
To: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Pavel Emelyanov <xemul@parallels.com>,
Jiri Slaby <jslaby@suse.cz>
Subject: Re: [RFC] tty: Add get- ioctls to fetch tty status
Date: Thu, 27 Sep 2012 07:17:49 -0700 [thread overview]
Message-ID: <5064600D.1090506@zytor.com> (raw)
In-Reply-To: <20120927141425.GG6618@moon>
On 09/27/2012 07:14 AM, Cyrill Gorcunov wrote:
> On Thu, Sep 27, 2012 at 03:14:47PM +0100, Alan Cox wrote:
>>> Alan, Greg, what's opinion? This flags fetching is the same as say fetching
>>> of termios settings, once fetched they can be changed immediately, and it's
>>> up to caller what to do with termios settings. No?
>>
>> I think you need to explain what you expect to be doing with it, and why
>> it is safe in that application.
>
> OK, it seems it was unclear from changelog. We need to know this parameters
> to be able to restore tty connection after checkpoint.
>
> While we easily can fetch termios settings and such, there are few bits which
> are missed to expord. So this patch provides them to user-space.
>
What bothers me (and the same applies to termios) is that you have NO
idea if your particular process is the "owner" of that tty. tty users
use out-of-band protocols, often implicit, to determine which process
"owns" the tty state.
If you can't guarantee that ALL those processes are stopped and
checkpointed/restarted, you have a huge problem.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-09-27 14:18 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-13 9:56 [RFC] tty: Add get- ioctls to fetch tty status Cyrill Gorcunov
2012-09-13 11:46 ` Jiri Slaby
2012-09-13 11:51 ` Cyrill Gorcunov
2012-09-13 12:51 ` Alan Cox
2012-09-13 12:54 ` Cyrill Gorcunov
2012-09-13 16:25 ` Alan Cox
2012-09-13 16:41 ` Cyrill Gorcunov
2012-09-22 18:06 ` Cyrill Gorcunov
2012-09-22 20:07 ` Greg Kroah-Hartman
2012-09-22 20:11 ` Cyrill Gorcunov
2012-09-22 21:52 ` Cyrill Gorcunov
2012-09-23 1:09 ` Greg Kroah-Hartman
2012-09-23 6:40 ` Cyrill Gorcunov
2012-09-23 14:46 ` H. Peter Anvin
2012-09-23 15:21 ` Cyrill Gorcunov
2012-09-24 14:14 ` Cyrill Gorcunov
2012-09-27 14:05 ` Cyrill Gorcunov
2012-09-27 14:14 ` Alan Cox
2012-09-27 14:14 ` Cyrill Gorcunov
2012-09-27 14:17 ` H. Peter Anvin [this message]
2012-09-27 14:21 ` Cyrill Gorcunov
2012-09-27 14:43 ` H. Peter Anvin
2012-09-27 14:48 ` Cyrill Gorcunov
2012-09-27 15:05 ` H. Peter Anvin
2012-09-27 15:13 ` Alan Cox
2012-09-27 15:23 ` Cyrill Gorcunov
2012-09-27 16:00 ` Alan Cox
2012-09-27 16:06 ` Cyrill Gorcunov
2012-09-27 15:47 ` Cyrill Gorcunov
2012-09-22 23:15 ` Alan Cox
2012-09-23 1:43 ` Eric W. Biederman
2012-09-23 6:40 ` Cyrill Gorcunov
2012-09-23 14:44 ` H. Peter Anvin
2012-09-23 15:22 ` Cyrill Gorcunov
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