atom feed46 messages in org.kernel.vger.linux-kernelRe: tty: add 'active' sysfs attribute...
FromSent OnAttachments
Kay SieversNov 16, 2010 7:46 am 
Alan CoxNov 16, 2010 7:56 am 
Kay SieversNov 16, 2010 8:12 am 
Alan CoxNov 16, 2010 9:14 am 
Kay SieversNov 16, 2010 10:51 am 
Alan CoxNov 16, 2010 11:55 am 
Kay SieversNov 16, 2010 12:15 pm 
Alan CoxNov 16, 2010 12:48 pm 
Kay SieversNov 16, 2010 1:28 pm 
Lennart PoetteringNov 16, 2010 1:35 pm 
Lennart PoetteringNov 16, 2010 1:42 pm 
Alan CoxNov 16, 2010 2:51 pm 
Alan CoxNov 16, 2010 2:55 pm 
Lennart PoetteringNov 16, 2010 2:58 pm 
Alan CoxNov 16, 2010 3:04 pm 
Lennart PoetteringNov 16, 2010 3:10 pm 
Lennart PoetteringNov 16, 2010 3:18 pm 
Alan CoxNov 16, 2010 3:45 pm 
Etched PixelsNov 16, 2010 3:49 pm 
John StoffelNov 17, 2010 8:31 am 
Vald...@vt.eduNov 17, 2010 2:00 pm 
Kay SieversNov 17, 2010 3:39 pm 
Alan CoxNov 17, 2010 3:56 pm 
Greg KHNov 17, 2010 5:27 pm 
Lennart PoetteringNov 17, 2010 5:48 pm 
Greg KHNov 17, 2010 5:52 pm 
Lennart PoetteringNov 17, 2010 6:28 pm 
Alan CoxNov 18, 2010 2:14 am 
Dr. Werner FinkNov 18, 2010 2:59 am 
Alan CoxNov 18, 2010 3:23 am 
Kay SieversNov 18, 2010 3:54 am 
Kay SieversNov 18, 2010 4:03 am 
Dr. Werner FinkNov 18, 2010 4:12 am 
Alan CoxNov 18, 2010 4:57 am 
Alan CoxNov 18, 2010 5:00 am 
Dr. Werner FinkNov 18, 2010 5:13 am 
Alan CoxNov 18, 2010 6:41 am 
Dr. Werner FinkNov 19, 2010 5:21 am 
Alan CoxNov 19, 2010 7:46 am 
Dr. Werner FinkNov 19, 2010 9:06 am.tiocgdev
Greg KHNov 19, 2010 10:02 am 
Dr. Werner FinkNov 19, 2010 10:41 am 
Alan CoxNov 20, 2010 4:39 am 
Dr. Werner FinkDec 1, 2010 3:15 am 
Dr. Werner FinkDec 1, 2010 4:31 am.tiocgdev
Dr. Werner FinkDec 3, 2010 3:47 am.Other
Subject:Re: tty: add 'active' sysfs attribute to tty0 and console device
From:Kay Sievers (kay.@vrfy.org)
Date:Nov 16, 2010 1:28:48 pm
List:org.kernel.vger.linux-kernel

On Tue, Nov 16, 2010 at 21:49, Alan Cox <al@lxorguk.ukuu.org.uk> wrote:

Stuff never stops changing until the machine shuts down, its undefined.

Either you don't, or you just don't want to understand what all this is about. :)

At what point do you think the current tty stops changing ? The only cases I can think of are shutdown, and when your own processes locks vt changes.

Hmm, what do you mean? It's not the tty IO. It's only the VT switch, and this changes only when someone actually does the switch, like pressing Alt-F1,F2,...

Except that it doesn't address things like the permissions side of things.

NAK again

Specifics please.

/dev/tty* and sysfs nodes don't track permissions, owner with each other, so you are providing interfaces that either expose information they shouldn't (which screen is valuable info in some environments), or don't expose info they should.

sysfs also lacks vhangup so you can't fix it right now either.

You think exposing the currently active VC is security relevant? We don't expose anything from the VC itself. We have this information all over the place in userspace. What exactly you think is the problem here?

"We have an interface that doesn't quite work for our case and we think that is a bug" is not the reasoning behind writing a new random one with a totally disconnected permission model that doesn't work either.

Fix the one we have.

So how do you think you'll fix it? I better don't get into your ioctl() business.

Start by explaining why the current interface doesn't work for you, but in detail.

The sleeping ioctl() requires a dedicated thread in a service. Now we wake up and all the stuff that happens now is lost, so we have to check with another ioctl(), between this ioctl() and going to sleep again is a window we don't cover, we just go to sleep, even when something has happened. Poll() solves that by queuing the notification until it's retrieved.

Kay

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