From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753950Ab0JGQhy convert rfc822-to-quoted-printable (ORCPT ); Thu, 7 Oct 2010 12:37:54 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:56492 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752370Ab0JGQhv convert rfc822-to-8bit (ORCPT ); Thu, 7 Oct 2010 12:37:51 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Eric Dumazet Cc: =?utf-8?Q?Am=C3=A9rico?= Wang , Robin Holt , Andrew Morton , linux-kernel , Willy Tarreau , "David S. Miller" , netdev@vger.kernel.org, James Morris , "Pekka Savola \(ipv6\)" , Patrick McHardy , Alexey Kuznetsov References: <1286025469.2582.1806.camel@edumazet-laptop> <20101004085913.GR14068@sgi.com> <1286183058.18293.26.camel@edumazet-laptop> <20101004093439.GG5189@cr0.nay.redhat.com> <1286187030.18293.33.camel@edumazet-laptop> <20101004103545.GJ5189@cr0.nay.redhat.com> <1286188701.18293.57.camel@edumazet-laptop> <20101005130117.GK5170@cr0.nay.redhat.com> <20101007071859.GD5471@cr0.nay.redhat.com> <20101007092538.GE5471@cr0.nay.redhat.com> <1286445081.2912.15.camel@edumazet-laptop> Date: Thu, 07 Oct 2010 09:37:32 -0700 In-Reply-To: <1286445081.2912.15.camel@edumazet-laptop> (Eric Dumazet's message of "Thu, 07 Oct 2010 11:51:21 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.157.188;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 98.207.157.188 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 0.4 FVGT_m_MULTI_ODD Contains multiple odd letter combinations * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 T_TooManySym_03 6+ unique symbols in subject * 0.0 T_TooManySym_02 5+ unique symbols in subject * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Eric Dumazet X-Spam-Relay-Country: Subject: Re: [PATCH] sysctl: fix min/max handling in __do_proc_doulongvec_minmax() X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from QUOTED-PRINTABLE to 8bit by mail.home.local id o97GcXxQ031189 Eric Dumazet writes: > Le jeudi 07 octobre 2010 à 17:25 +0800, Américo Wang a écrit : >> >> >> > >> >Here is the final one. >> >> Oops, that one is not correct. Hopefully this one >> is correct. >> >> ---------------> >> >> Eric D. noticed that we may trigger an OOPS if we leave ->extra{1,2} >> to NULL when we use proc_doulongvec_minmax(). >> >> Actually, we don't need to store min/max values in a vector, >> because all the elements in the vector should share the same min/max >> value, like what proc_dointvec_minmax() does. >> > > If we assert same min/max limits are to be applied to all elements, > a much simpler fix than yours would be : > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > index f88552c..8e45451 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -2485,7 +2485,7 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int > kbuf[left] = 0; > } > > - for (; left && vleft--; i++, min++, max++, first=0) { > + for (; left && vleft--; i++, first=0) { > unsigned long val; > > if (write) { > > > Please dont send huge patches like this to 'fix' a bug, > especially on slow path. > > First we fix the bug, _then_ we can try to make code more > efficient or more pretty or shorter. > > So the _real_ question is : > > Should the min/max limits should be a single pair, > shared by all elements, or a vector of limits. The difference between long handling and int handling is a usability issue. I don't expect we will be exporting new vectors via sysctl, so the conversion of a handful of vectors from int to long is where this is most likely to be used. I skimmed through all of what I presume are the current users aka linux-2.6.36-rcX and there don't appear to be any users of proc_dounlongvec_minmax that use it's vector properties there. Which doubly tells me that incrementing the min and max pointers is not what we want to do. Eric