linux-kernel - Re: [PATCH 00/10] drivers/pci: avoid module

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <566E7D4E.8010406@xilinx.com>
Date:	Mon, 14 Dec 2015 09:26:54 +0100
From:	Michal Simek <michal.simek@...inx.com>
To:	Thierry Reding <thierry.reding@...il.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>
CC:	Paul Gortmaker <paul.gortmaker@...driver.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	linux-pci <linux-pci@...r.kernel.org>,
	"Alexandre Courbot" <gnurou@...il.com>,
	Pratyush Anand <pratyush.anand@...il.com>,
	"Michal Simek" <michal.simek@...inx.com>,
	Kishon Vijay Abraham I <kishon@...com>,
	Murali Karicheri <m-karicheri2@...com>,
	Sören Brinkmann <soren.brinkmann@...inx.com>,
	Jason Cooper <jason@...edaemon.net>,
	"Stephen Warren" <swarren@...dotorg.org>,
	Simon Horman <horms@...ge.net.au>,
	<linux-tegra@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Richard Zhu <Richard.Zhu@...escale.com>,
	<rfi@...ts.rocketboards.org>, Ley Foon Tan <lftan@...era.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lucas Stach <l.stach@...gutronix.de>
Subject: Re: [PATCH 00/10] drivers/pci: avoid module_init in non-modular
 host/pci*

On 14.12.2015 09:24, Thierry Reding wrote:
> On Mon, Dec 14, 2015 at 09:19:30AM +0100, Geert Uytterhoeven wrote:
>> Hi Paul,
>>
>> On Sun, Dec 13, 2015 at 2:41 AM, Paul Gortmaker
>> <paul.gortmaker@...driver.com> 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 code
>>>  (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 delete
>>> 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.
>>
>> 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 kernels
>> are becoming too big.
>>
>> 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.

Great.

Send them out.

Thanks,
Michal

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/