From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751651AbdH3Mw1 (ORCPT <rfc822;w@1wt.eu>);
        Wed, 30 Aug 2017 08:52:27 -0400
Received: from mx2.suse.de ([195.135.220.15]:50250 "EHLO mx1.suse.de"
        rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP
        id S1751359AbdH3MvS (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 30 Aug 2017 08:51:18 -0400
Date: Wed, 30 Aug 2017 14:51:16 +0200 (CEST)
From: Miroslav Benes <mbenes@suse.cz>
To: Josh Poimboeuf <jpoimboe@redhat.com>
cc: Petr Mladek <pmladek@suse.com>, jeyu@kernel.org, jikos@kernel.org,
        lpechacek@suse.cz, live-patching@vger.kernel.org,
        linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Michael Ellerman <mpe@ellerman.id.au>, Oleg Nesterov <oleg@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 0/3] livepatch: Introduce force sysfs attribute
In-Reply-To: <20170816152610.4liqwmwa4hcn4rnb@treble>
Message-ID: <alpine.LSU.2.21.1708301449270.6379@san.suse.cz>
References: <20170810104815.14727-1-mbenes@suse.cz> <20170811211131.n7mo4xsucteba7hz@treble> <20170816145007.GD601@pathway.suse.cz> <20170816152610.4liqwmwa4hcn4rnb@treble>
User-Agent: Alpine 2.21 (LSU 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, 16 Aug 2017, Josh Poimboeuf wrote:

> On Wed, Aug 16, 2017 at 04:50:07PM +0200, Petr Mladek wrote:
> > On Fri 2017-08-11 16:11:31, Josh Poimboeuf wrote:
> > > On Thu, Aug 10, 2017 at 12:48:12PM +0200, Miroslav Benes wrote:
> > > > Now there is a sysfs attribute called "force", which provides two
> > > > functionalities, "signal" and "force" (previously "unmark"). I haven't
> > > > managed to come up with better names. Proposals are welcome. On the
> > > > other hand I do not mind it much.
> > > 
> > > Now "force" has two meanings, which is a little confusing.  What do you
> > > think about just having two separate write-only sysfs flags?
> > > 
> > >   echo 1 > /sys/kernel/livepatch/signal
> > >   echo 1 > /sys/kernel/livepatch/force
> > 
> > I like the simplicity but I wonder if there might be more actions
> > that need to be forced in the future. Then this might cause
> > confusion.
> > 
> > For example, we have force_module_load attribute in kGraft.
> > It allows to load a module even when it is refused by a livepatch.
> > It is handy when there is a harmless bug in the patch.

We can add force_module_load attribute too in that case. But I see your 
point, I just don't think it would be that serious as far as confusion is 
concerned.

> What if we put the flags in the per-patch dir?
> 
>   /sys/kernel/livepatch/<patch>/signal
>   /sys/kernel/livepatch/<patch>/force
> 
> That seems pretty unambiguous.  The "force" is specific to the patch, it
> clearly means we are forcing the patch.

Petr, would this solve your worries?

Thanks,
Miroslav