From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932498AbeCLVAa (ORCPT ); Mon, 12 Mar 2018 17:00:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33628 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932302AbeCLVA3 (ORCPT ); Mon, 12 Mar 2018 17:00:29 -0400 Date: Mon, 12 Mar 2018 14:00:27 -0700 From: Andrew Morton To: Waiman Long Cc: "Luis R. Rodriguez" , Kees Cook , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Al Viro , Matthew Wilcox Subject: Re: [PATCH v4 3/6] sysctl: Warn when a clamped sysctl parameter is set out of range Message-Id: <20180312140027.97db31d5dfc5c5f52a7c19a3@linux-foundation.org> In-Reply-To: <1520885744-1546-4-git-send-email-longman@redhat.com> References: <1520885744-1546-1-git-send-email-longman@redhat.com> <1520885744-1546-4-git-send-email-longman@redhat.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 12 Mar 2018 16:15:41 -0400 Waiman Long wrote: > Even with clamped sysctl parameters, it is still not that straight > forward to figure out the exact range of those parameters. One may > try to write extreme parameter values to see if they get clamped. > To make it easier, a warning with the expected range will now be > printed into the kernel ring buffer when a clamped sysctl parameter > receives an out of range value. > > The pr_warn_ratelimited() macro is used to limit the number of warning > messages that can be printed within a given period of time. > > ... > > +#ifdef pr_fmt > +#undef pr_fmt > +#endif > +#define pr_fmt(fmt) "sysctl: " fmt Why is it necessary to undefine pr_fmt? That's a somewhat unusual thing to do.