From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752981Ab0I2Lmg (ORCPT ); Wed, 29 Sep 2010 07:42:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16217 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751046Ab0I2Lmf (ORCPT ); Wed, 29 Sep 2010 07:42:35 -0400 Message-ID: <4CA32626.8040700@redhat.com> Date: Wed, 29 Sep 2010 13:42:30 +0200 From: Jerome Marchand User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Pavel Emelyanov CC: Matthew Wilcox , Linux Kernel Mailing List Subject: Re: [PATCH] procfs: fix numbering in /proc/locks References: <4CA0B4A5.1090701@redhat.com> <4CA0B743.2050801@parallels.com> In-Reply-To: <4CA0B743.2050801@parallels.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/27/2010 05:24 PM, Pavel Emelyanov wrote: > On 09/27/2010 07:13 PM, Jerome Marchand wrote: >> >> The lock number in /proc/locks (first field) is implemented by a counter >> (private field of struct seq_file) which is incremented at each call of >> locks_show(). Currently it is reset each time locks_start() is called, >> that is each time we call the read() syscall on /proc/locks. Because of >> that, the numbering erratically restarts at 1 several times when reading >> a long /proc/locks file. >> We want the counter to be initialized at opening time and then never >> reset until we close the file. Fortunately, seq_open() memzeros the >> seq_file structure, so we can just drop the reset in locks_start() and >> move the increment the counter before actually printing the line so the >> numbering still starts at 1. > > IMHO the implementation is wrong. If you want the proper sequence number > while file is open you should increase on in the ->next callback of the > seq_ops, not in show. Good point. My implementation is definitely wrong. But I'm afraid that moving the increment in locks_next() won't help either. It will fail when a program do something more than just read the file sequentially (use of lseek() for instance). We need a better way to keep track of the current position in the list. Thanks, Jerome