From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758920Ab0JHQLm (ORCPT ); Fri, 8 Oct 2010 12:11:42 -0400 Received: from mail-pw0-f46.google.com ([209.85.160.46]:59900 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758787Ab0JHQLk (ORCPT ); Fri, 8 Oct 2010 12:11:40 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:content-transfer-encoding :in-reply-to:user-agent; b=q01zeDfG/jVL8YdRyzbCPONZmqAgj/9OOX3UZt+qWwVTaxSP4wEv5UhEB+EVRlr4iU e3gCjEq6lW5QyC0AMoa+8g9VoFrifvkYPrDzZ4HXcBp0Zt08NgDykqumzDlbMTC/kGPz st2KAA/MoXsbWbrrVYMU8dQlY9GEz4qVZ2mok= Date: Sat, 9 Oct 2010 00:13:44 +0800 From: =?utf-8?Q?Am=C3=A9rico?= Wang 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 , ebiederm@xmission.com Subject: Re: [PATCH] sysctl: fix min/max handling in __do_proc_doulongvec_minmax() Message-ID: <20101008161344.GG4088@hack> References: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1286445081.2912.15.camel@edumazet-laptop> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 07, 2010 at 11:51:21AM +0200, Eric Dumazet wrote: >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. Well, my patch makes that horrible code a little better. :) > >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. > Yes, actually I talked with Eric W. about this before sending the patch. I also checked the users of proc_doulongvec_minmax(), none of them are using more than one limit, so it is safe to remove that. -- Live like a child, think like the god.