From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:42213 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932365AbeB1TGE (ORCPT ); Wed, 28 Feb 2018 14:06:04 -0500 Date: Wed, 28 Feb 2018 19:06:01 +0000 From: "Luis R. Rodriguez" To: Waiman Long Cc: "Luis R. Rodriguez" , Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Al Viro Subject: Re: [PATCH v2 2/5] sysctl: Add flags to support min/max range clamping Message-ID: <20180228190601.GM14069@wotan.suse.de> References: <1519764591-27456-1-git-send-email-longman@redhat.com> <1519764591-27456-3-git-send-email-longman@redhat.com> <20180228004753.GY14069@wotan.suse.de> <23264b8f-e84d-48cf-0da0-eb328916b2aa@redhat.com> <20180228184325.GJ14069@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Feb 28, 2018 at 01:58:53PM -0500, Waiman Long wrote: > On 02/28/2018 01:43 PM, Luis R. Rodriguez wrote: > > On Wed, Feb 28, 2018 at 12:53:40PM -0500, Waiman Long wrote: > >> On 02/27/2018 07:47 PM, Luis R. Rodriguez wrote: > >>> On Tue, Feb 27, 2018 at 03:49:48PM -0500, Waiman Long wrote: > >>>> When minimum/maximum values are specified for a sysctl parameter in > >>>> the ctl_table structure with proc_dointvec_minmax() handler, > >>> an > >>> > >>>> update > >>>> to that parameter will fail with error if the given value is outside > >>>> of the required range. > >>>> > >>>> There are use cases where it may be better to clamp the value of > >>>> the sysctl parameter to the given range without failing the update, > >>>> especially if the users are not aware of the actual range limits. > >>> Makes me wonder if we should add something which does let one query > >>> for the ranges. Then scripts can fetch that as well. > >> That will actually be better than printing out the range in the dmesg > >> log. However, I haven't figured out an easy way of doing that. If you > >> have any suggestion, please let me know about it. > > I think a macro that also adds yet another proc read-only entry with a postfix > > "_range" with an internal handler which prints the range may suffice. > > > > Luis > > I think that is a possible solution. Instead of adding a macro, I will > add one more flag which does the magic when the ctl_table entry is being > processed. I think that will be simpler from the user point of view. Agreed, flag should work nicely too. And likely easier to read / review and maintain. Luis