Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752623AbdHIVwR (ORCPT ); Wed, 9 Aug 2017 17:52:17 -0400 Received: from quartz.orcorp.ca ([184.70.90.242]:53010 "EHLO quartz.orcorp.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752457AbdHIVwO (ORCPT ); Wed, 9 Aug 2017 17:52:14 -0400 Date: Wed, 9 Aug 2017 15:52:02 -0600 From: Jason Gunthorpe To: Michal Suchanek Cc: Greg Kroah-Hartman , Peter Huewe , Marcel Selhorst , Jarkko Sakkinen , linux-kernel@vger.kernel.org, tpmdd-devel@lists.sourceforge.net Subject: Re: [PATCH] Do not disable driver and bus shutdown hook when class shutdown hook is set. Message-ID: <20170809215202.GA21867@obsidianresearch.com> References: <20170809213420.2391-1-msuchanek@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170809213420.2391-1-msuchanek@suse.de> User-Agent: Mutt/1.5.24 (2015-08-30) X-Broken-Reverse-DNS: no host name found for IP address 10.0.0.156 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 33 On Wed, Aug 09, 2017 at 11:34:20PM +0200, Michal Suchanek wrote: > Disabling the driver hook by setting class hook is totally sound design > not prone to error as evidenced by the single implementation of the > class hook. It was done this was for consistency, if you look at the full code: if (dev->class && dev->class->shutdown) { if (initcall_debug) dev_info(dev, "shutdown\n"); dev->class->shutdown(dev); } else if (dev->bus && dev->bus->shutdown) { if (initcall_debug) dev_info(dev, "shutdown\n"); dev->bus->shutdown(dev); } else if (dev->driver && dev->driver->shutdown) { if (initcall_debug) dev_info(dev, "shutdown\n"); dev->driver->shutdown(dev); } The bus disables the driver callback, on the expectation that the bus implementation will do it. Existing bus implementations do properly chain to driver shutdown (eg look at mmc_bus_shutdown) and it appears to have been written like this so that the bus can insert code before and after calling the driver shutdown. Making class act differently from bus seems very confusing, IHMO, which why the TPM patch was written to follow the existing pattern. Jason