From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keiichi KII Subject: Re: [RFC][PATCH -mm take2 3/5] add interface for netconsole using sysfs Date: Wed, 10 Jan 2007 19:33:41 +0900 Message-ID: <45A4C105.3000509@bx.jp.nec.com> References: <4590AE00.5040102@bx.jp.nec.com> <4590B365.8010707@bx.jp.nec.com> <4595F630.70705@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Cc: mpm@selenic.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: Received: from TYO201.gate.nec.co.jp ([202.32.8.193]:50053 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964833AbXAJKeE (ORCPT ); Wed, 10 Jan 2007 05:34:04 -0500 To: Stephen Hemminger In-Reply-To: <4595F630.70705@osdl.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org >> create a sysfs entry for netconsole in /sys/class/misc. >> This entry has elements related to netconsole as follows. >> You can change configuration of netconsole(writable attributes such as IP >> address, port number and so on) and check current configuration of netconsole. >> >> -+- /sys/class/misc/ >> |-+- netconsole/ >> |-+- port1/ >> | |--- id [r--r--r--] unique port id >> | |--- remove [-w-------] if you write something to "remove", >> | | this port is removed. >> > IMHO this kind of "magic side effect" is a misuse of sysfs. and would > make proper locking > impossible. How do you deal with the dangling reference to the > netconsole object? I manage the reference by using a list. If you write something to "remove", firstly the port entry is removed from sysfs and then the reference is removed from the list and a resource of the port is freed. > f= open (... netconsole/port1/remove") > write(f, "", 1) > sleep(2) > write(f, "", 1) .... this probably would crash... > > > Maybe having a state variable/sysfs file so you could setup the port and > turn it on/off with write. You are right. When I tested above program, my machine crashed. I'm going to rethink the interface for netconsole. Thanks for your comments. -- Keiichi KII NEC Corporation OSS Promotion Center E-mail: k-keiichi@bx.jp.nec.com