From owner-freebsd-hackers@FreeBSD.ORG Sun Nov 25 14:09:02 2012 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id D2C222EE; Sun, 25 Nov 2012 14:09:02 +0000 (UTC) (envelope-from asmrookie@gmail.com) Received: from mail-lb0-f182.google.com (mail-lb0-f182.google.com [209.85.217.182]) by mx1.freebsd.org (Postfix) with ESMTP id A45478FC08; Sun, 25 Nov 2012 14:09:01 +0000 (UTC) Received: by mail-lb0-f182.google.com with SMTP id go10so7260452lbb.13 for ; Sun, 25 Nov 2012 06:09:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:reply-to:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=qZykcAZoW0RKyTdsvWkmXfPC1+4mvsyvaDFlNLBCB4k=; b=ixSSh9UNyvjl/RKLnTltCE+Ci5V7LczsCeFF6wEPt6YksJ8iE0dFOc4cZykoVj1meu TNBVkTwS7EGmnSeLBWBO1kr36e2Q5lPneE6KqZyFQnOuOoMpZf361xe6HhBSbbp4a96r t18i00lxJRSpjGhOIOAx1sKBosZ3n8+kFK+zd6WMpSt546pRpE0LBI+U3I3G8GofQnoT gQmhYiptEaOP84zHI3zZiHOZjqqM6qXVffro/VtmRlGa+DpOt/3pZaeoPQnOJem1WMfx F0DA2LLU1304HdbwsUDDHgR3aPWFfZv8AAslygYnz8AHKy6Ou/ZrC9E8IG003yCTgmfY qvAg== MIME-Version: 1.0 Received: by 10.152.132.3 with SMTP id oq3mr8189422lab.18.1353852540239; Sun, 25 Nov 2012 06:09:00 -0800 (PST) Sender: asmrookie@gmail.com Received: by 10.112.134.5 with HTTP; Sun, 25 Nov 2012 06:09:00 -0800 (PST) In-Reply-To: <20121125140620.GL1460@garage.freebsd.pl> References: <20121125123920.GI1460@garage.freebsd.pl> <20121125131252.GJ1460@garage.freebsd.pl> <20121125134743.GK1460@garage.freebsd.pl> <20121125140620.GL1460@garage.freebsd.pl> Date: Sun, 25 Nov 2012 14:09:00 +0000 X-Google-Sender-Auth: NgLPQcbFg0D9VZQzanBEbdILWZA Message-ID: Subject: Re: [RFQ] make witness panic an option From: Attilio Rao To: Pawel Jakub Dawidek Content-Type: text/plain; charset=UTF-8 Cc: "freebsd-hackers@freebsd.org" , Adrian Chadd , Giovanni Trematerra , freebsd-arch@freebsd.org X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: attilio@FreeBSD.org List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Nov 2012 14:09:03 -0000 On Sun, Nov 25, 2012 at 2:06 PM, Pawel Jakub Dawidek wrote: > On Sun, Nov 25, 2012 at 01:48:23PM +0000, Attilio Rao wrote: >> On Sun, Nov 25, 2012 at 1:47 PM, Pawel Jakub Dawidek wrote: >> > On Sun, Nov 25, 2012 at 01:37:19PM +0000, Attilio Rao wrote: >> >> On Sun, Nov 25, 2012 at 1:12 PM, Pawel Jakub Dawidek wrote: >> >> > On Sun, Nov 25, 2012 at 12:42:16PM +0000, Attilio Rao wrote: >> >> >> On Sun, Nov 25, 2012 at 12:39 PM, Pawel Jakub Dawidek wrote: >> >> >> > WITNESS is a development tool. We don't ship production kernels with >> >> >> > WITNESS even compiled in. What is more efficient use of developer time: >> >> >> > going through full reboot cycle every time or reading the warning from >> >> >> > console, unloading a module, fixing the bug and loading it again? >> >> >> > >> >> >> > And if this option is turned off by default what is the problem? >> >> >> >> >> >> Yes, so, why do you write here? >> >> > >> >> > I'm trying to understand why do you object. Until now the only concern >> >> > you have that I found is that you are afraid of it being abused. I don't >> >> > see how this can be abused if it is turned off by default. If someone >> >> > will commit a change that will turn it on by default, believe me, I'll >> >> > unleash hell personally. >> >> >> >> So I don't understand what are you proposing. >> >> You are not proposing to switch BLESSING on and you are not proposing >> >> to import Adrian's patches in, if I get it correctly. I don't >> >> understand then. >> > >> > I propose to get Adrian's patches in, just leave current behaviour as >> > the default. >> >> So if I tell that I'm afraid this mechanism will be abused (and >> believe me, I really wanted to trimm out BLESSING stuff also for the >> same reason) and you say "you can't see how" there is not much we can >> discuss. > > This is not what I said. I would see it as abuse if someone will > suddenly decided to turn off locking assertions by default in FreeBSD > base. > > If he will turn that off on his private machine be it to speed up his > development (a good thing) or to shut up important lock assertion (a bad > thing) this is entirely his decision. He can already do that having all > the source code, its just more complex. Make tools, not policies. > > BLESSING is totally different subject. You were afraid that people will > start to silence LORs they don't understand by committing blessed pairs > to FreeBSD base. And this situation is abuse and I fully agree, but I > also still think BLESSING is useful, although I recognize it might be > hard to prevent mentioned abuse. > > In case of Adrian's patch nothing will change in how we enforce locking > assertions in FreeBSD base. > >> You know how I think, there is no need to wait for me to reconsider, >> because I don't believe this will happen with arguments like "I don't >> think", "I don't agree", etc. > > I provide valid arguments with I hope proper explanation, you choose not > to address them or ignore them and I hope this will change:) I'm not ignoring them, I'm saying that your arguments are not enough convincing to me. And really, giving the possibility to turn off assertions in witness is already a dangerous tool I want to avoid (not only related to BLESSING). If there are some cases that deserve a panic, we might just get it, not matter how sysctls are setup. However it seems to me I'm just saying the same thing since 20 e-mails, please drop me from CC in your next follow up. As I said, you can commit all the changes you want (assuming they are technically correct) even if I would appreciate my disagreement is expressed in the commit message. Attilio -- Peace can only be achieved by understanding - A. Einstein