From owner-freebsd-arch@FreeBSD.ORG  Mon Apr 14 07:55:11 2008
Return-Path: <owner-freebsd-arch@FreeBSD.ORG>
Delivered-To: arch@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id B06DC106566B
	for <arch@freebsd.org>; Mon, 14 Apr 2008 07:55:11 +0000 (UTC)
	(envelope-from phk@critter.freebsd.dk)
Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222])
	by mx1.freebsd.org (Postfix) with ESMTP id 771598FC18
	for <arch@freebsd.org>; Mon, 14 Apr 2008 07:55:06 +0000 (UTC)
	(envelope-from phk@critter.freebsd.dk)
Received: from critter.freebsd.dk (unknown [192.168.61.3])
	by phk.freebsd.dk (Postfix) with ESMTP id EF62A17104;
	Mon, 14 Apr 2008 07:55:04 +0000 (UTC)
Received: from critter.freebsd.dk (localhost [127.0.0.1])
	by critter.freebsd.dk (8.14.2/8.14.2) with ESMTP id m3E7t4ie005288;
	Mon, 14 Apr 2008 07:55:04 GMT (envelope-from phk@critter.freebsd.dk)
To: Ed Schouten <ed@80386.nl>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Mon, 14 Apr 2008 09:47:10 +0200."
	<20080414074710.GI5934@hoeg.nl> 
Date: Mon, 14 Apr 2008 07:55:04 +0000
Message-ID: <5287.1208159704@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: arch@freebsd.org
Subject: Re: f_offset 
X-BeenThere: freebsd-arch@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussion related to FreeBSD architecture <freebsd-arch.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-arch>
List-Post: <mailto:freebsd-arch@freebsd.org>
List-Help: <mailto:freebsd-arch-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 14 Apr 2008 07:55:11 -0000

In message <20080414074710.GI5934@hoeg.nl>, Ed Schouten writes:

>I'm experiencing similar problems with implementing read() and write()
>inside my mpsafetty branch for TTY's. Just like the current TTY
>implementation, my implementation will do strange things when two
>threads call read() or write() at the same time. Data could end up mixed
>together.

The write side of this will break quite a lot of stuff, starting
with syslogd(8), write(1), wall(1) and similar, all which expect
to be able to spam terminals coherently.

The read side will probably mostly cause trouble for programs that
try to take input from /dev/tty, usually passwords.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.