From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755670Ab3DLVQk (ORCPT ); Fri, 12 Apr 2013 17:16:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:23419 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753808Ab3DLVQj (ORCPT ); Fri, 12 Apr 2013 17:16:39 -0400 Date: Fri, 12 Apr 2013 17:16:27 -0400 From: Don Zickus To: Guenter Roeck Cc: Dave Young , linux-watchdog@vger.kernel.org, kexec@lists.infradead.org, wim@iguana.be, LKML , vgoyal@redhat.com Subject: Re: [RFC PATCH] watchdog: Add hook for kicking in kdump path Message-ID: <20130412211627.GM79013@redhat.com> References: <20130408124858.GC79013@redhat.com> <20130408151509.GA20919@roeck-us.net> <20130409144431.GL79013@redhat.com> <20130409145228.GA1111@roeck-us.net> <20130409151423.GM79013@redhat.com> <20130409160757.GA27050@roeck-us.net> <20130410134039.GV79013@redhat.com> <20130410135123.GB15456@roeck-us.net> <20130410142055.GW79013@redhat.com> <20130410151041.GA6670@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130410151041.GA6670@roeck-us.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 10, 2013 at 08:10:41AM -0700, Guenter Roeck wrote: > > have no idea how to even find out if multiple watchdogs are open on the > > system. Is there a list I could walk? And with regard to 'watchdog is > > /* the dev_t structure to store the dynamically allocated watchdog devices */ > static dev_t watchdog_devt; > > One way to look up the allocated watchdogs might be to loop through all kobj > instances for the major device using kobj_lookup. Don't know if there is a > better way. Hmm, I got around to poking at this today and I am not sure kobj_lookup will work. Besides being surrounded with another mutex, I don't have access to the character device domain to pass to kobj_lookup. Perhaps I am not reading the code right, but I can't find a good way forward. The only other hack I can think of, is to embed a list object in the watchdog structure and list_add each new register'd watchdog. Then it would be trivial to walk the watchdog list. Thoughts? Cheers, Don > > > running', I thought 'watchdog_active' would do that. But again, I could > > be misreading the code. > > > You are right. Missed that part, sorry. > > Guenter