Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752811AbbLNIYe (ORCPT ); Mon, 14 Dec 2015 03:24:34 -0500 Received: from mail-pf0-f173.google.com ([209.85.192.173]:35257 "EHLO mail-pf0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751014AbbLNIY3 (ORCPT ); Mon, 14 Dec 2015 03:24:29 -0500 Date: Mon, 14 Dec 2015 09:24:25 +0100 From: Thierry Reding To: Geert Uytterhoeven Cc: Paul Gortmaker , "linux-kernel@vger.kernel.org" , Linux-sh list , linux-pci , Alexandre Courbot , Pratyush Anand , Michal Simek , Kishon Vijay Abraham I , Murali Karicheri , =?utf-8?B?U8O2cmVu?= Brinkmann , Jason Cooper , Stephen Warren , Simon Horman , linux-tegra@vger.kernel.org, "linux-omap@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Thomas Petazzoni , Richard Zhu , rfi@lists.rocketboards.org, Ley Foon Tan , Bjorn Helgaas , Lucas Stach Subject: Re: [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci* Message-ID: <20151214082425.GA3766@ulmo.nvidia.com> References: <1449970917-12633-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="3MwIy2ne0vdjdPXF" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23+102 (2ca89bed6448) (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3820 Lines: 87 --3MwIy2ne0vdjdPXF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Dec 14, 2015 at 09:19:30AM +0100, Geert Uytterhoeven wrote: > Hi Paul, >=20 > On Sun, Dec 13, 2015 at 2:41 AM, Paul Gortmaker > wrote: > > This series of commits is a slice of a larger project to ensure > > people don't have dead code for module removal in non-modular > > drivers. Overall there was roughly 5k lines of dead code in the > > kernel due to this. So far we've fixed several areas, like tty, > > x86, net, etc. and we continue to work on other areas. > > > > There are several reasons to not use module_init for code that can > > never be built as a module, but the big ones are: > > > > (1) it is easy to accidentally code up unused module_exit and remove c= ode > > (2) it can be misleading when reading the source, thinking it can be > > modular when the Makefile and/or Kconfig prohibit it > > (3) it requires the include of the module.h header file which in turn > > includes nearly everything else. > > > > Here we convert some module_init() calls into device_initcall() and del= ete > > any module_exit and remove code that gets orphaned in the process, for > > an overall net code reduction, which is always welcome. > > > > The use of device_initcall ensures that the init function ordering > > remains unchanged, but one could argue that PCI host code might be more > > appropriate to be handled under subsys_initcall. Fortunately we can > > revisit making this extra change at a later date if desired; it does > > not need to happen now, and we reduce the risk of introducing > > regressions at this point in time by separating the two changes. > > > > Over half of the drivers changed here already explicitly disallowed any > > unbind operations. For the rest we make them the same, since there is > > not really any sensible use case to unbind any built-in bus support that > > I can think of. >=20 > Personally, I think all of these should become tristate, so distro kernels > don't have to build in PCI(e) support for all SoCs. multi_v7_defconfig ke= rnels > are becoming too big. >=20 > That does not preclude making these modules un-unloadable, though. Most of these can't be made tristate as-is, because they use symbols that aren't exported. Many of those symbols can easily be exported, so its just a matter of getting the respective patches merged. I disagree with making the modules non-unloadable, though. I have a local branch with changes necessary to unload the host controller driver and it works just fine. 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