From owner-freebsd-hackers  Fri Jan 23 03:25:26 1998
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Received: (from majordom@localhost)
          by hub.freebsd.org (8.8.8/8.8.8) id DAA21854
          for hackers-outgoing; Fri, 23 Jan 1998 03:25:26 -0800 (PST)
          (envelope-from owner-freebsd-hackers@FreeBSD.ORG)
Received: from db2server.voga.com.br (db2server.voga.com.br [200.239.39.7])
          by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id DAA21849
          for <hackers@freebsd.org>; Fri, 23 Jan 1998 03:25:22 -0800 (PST)
          (envelope-from daniel_sobral@voga.com.br)
From: daniel_sobral@voga.com.br
Received: from papagaio.voga.com.br (papagaio.voga.com.br [200.239.39.2])
	by db2server.voga.com.br (8.8.3+2.6Wbeta9/8.8.7) with SMTP id JAA16828;
	Fri, 23 Jan 1998 09:25:52 -0200
Received: by papagaio.voga.com.br(Lotus SMTP MTA v1.06 (346.7 3-18-1997))  id 03256595.00444867 ; Fri, 23 Jan 1998 09:25:49 -0300
X-Lotus-FromDomain: VOGA
To: luigi@labinfo.iet.unipi.it
cc: hackers@FreeBSD.ORG
Message-ID: <83256595.0043B804.00@papagaio.voga.com.br>
Date: Fri, 23 Jan 1998 09:25:43 -0300
Subject: Re: uiomove()
Mime-Version: 1.0
Content-type: text/plain; charset=us-ascii
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk


> I don't get your point about races. Once you are in the kernel you
> cannot have preemption unless you get an interrupt.

Yeah (well, kind of yeah), but... What about SMP? What about a process in
one processor calling read() while a process in another processor calls
write()?

> If you want to avoid this, protect the critical section of code between

Yup. The kind of interruption I may get is from timeout(9). But I can't do
s = spl0(), because spl0() "returns" void.

--
Daniel C. Sobral                      (8-DCS)
Daniel_Sobral@voga.com.br


Tagline:
   * FreeBSD. Earth.