From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932395AbeB1S6z (ORCPT ); Wed, 28 Feb 2018 13:58:55 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:34548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932176AbeB1S6y (ORCPT ); Wed, 28 Feb 2018 13:58:54 -0500 Subject: Re: [PATCH v2 2/5] sysctl: Add flags to support min/max range clamping To: "Luis R. Rodriguez" Cc: Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Al Viro 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> From: Waiman Long Organization: Red Hat Message-ID: Date: Wed, 28 Feb 2018 13:58:53 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20180228184325.GJ14069@wotan.suse.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cheers, Longman