From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Baryshkov Subject: Re: [PATCH 0/0] Power domain and clock domain patches for omap Date: Wed, 20 Aug 2008 08:20:55 +0000 (UTC) Message-ID: References: <1216221555-18958-1-git-send-email-tony@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: Received: from main.gmane.org ([80.91.229.2]:39779 "EHLO ciao.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751464AbYHTIVJ (ORCPT ); Wed, 20 Aug 2008 04:21:09 -0400 Received: from list by ciao.gmane.org with local (Exim 4.43) id 1KViwC-0007J6-4A for linux-omap@vger.kernel.org; Wed, 20 Aug 2008 08:21:04 +0000 Received: from ppp89-110-23-172.pppoe.avangarddsl.ru ([89.110.23.172]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 20 Aug 2008 08:21:04 +0000 Received: from dbaryshkov by ppp89-110-23-172.pppoe.avangarddsl.ru with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 20 Aug 2008 08:21:04 +0000 Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: linux-omap@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.arm.linux.org.uk Paul Walmsley wrote: > Hello Dmitry, > > On Tue, 19 Aug 2008, Dmitry Baryshkov wrote: > >> There is one major flaw IMO in this code. Please correct me if I'm >> wrong: Driver A: powerdomain_register() >> Driver B: powerdomain_get() >> Driver A: powerdomain_unregister() >> >> Then Driver B has a reference to unregistered domain. And as >> powerdomains lack any type of refcounting this can lead to any type of >> memory access bugs if Driver A is unloaded from the kernel. > > At this point, only OMAP kernel init code registers powerdomains in > arch/arm/mach-omap2/io.c. It's not intended that driver code will > manipulate or even know about these. Anyway, this type of powerdomain_unregister() is asking for problems. Either unregistering should be disallowed, or proper reference counting should be implemented IMO. -- With best wishes Dmitry