From: Thierry Reding <thierry.reding@gmail.com>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci*
Date: Mon, 14 Dec 2015 08:24:25 +0000 [thread overview]
Message-ID: <20151214082425.GA3766@ulmo.nvidia.com> (raw)
In-Reply-To: <CAMuHMdXr=ErCO3R2LB+wBJh3JSiFkH5q3-FLSTOwdGT87fXz3A@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2553 bytes --]
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@windriver.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.
Thierry
[-- Attachment #2: signature.asc --]
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WARNING: multiple messages have this Message-ID (diff)
From: Thierry Reding <thierry.reding@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Paul Gortmaker" <paul.gortmaker@windriver.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Linux-sh list" <linux-sh@vger.kernel.org>,
linux-pci <linux-pci@vger.kernel.org>,
"Alexandre Courbot" <gnurou@gmail.com>,
"Pratyush Anand" <pratyush.anand@gmail.com>,
"Michal Simek" <michal.simek@xilinx.com>,
"Kishon Vijay Abraham I" <kishon@ti.com>,
"Murali Karicheri" <m-karicheri2@ti.com>,
"Sören Brinkmann" <soren.brinkmann@xilinx.com>,
"Jason Cooper" <jason@lakedaemon.net>,
"Stephen Warren" <swarren@wwwdotorg.org>,
"Simon Horman" <horms@verge.net.au>,
linux-tegra@vger.kernel.org,
"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"Thomas Petazzoni" <thomas.petazzoni@free-electrons.com>,
"Richard Zhu" <Richard.Zhu@freescale.com>,
rfi@lists.rocketboards.org
Subject: Re: [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci*
Date: Mon, 14 Dec 2015 09:24:25 +0100 [thread overview]
Message-ID: <20151214082425.GA3766@ulmo.nvidia.com> (raw)
In-Reply-To: <CAMuHMdXr=ErCO3R2LB+wBJh3JSiFkH5q3-FLSTOwdGT87fXz3A@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2553 bytes --]
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@windriver.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.
Thierry
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Thierry Reding <thierry.reding@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Paul Gortmaker" <paul.gortmaker@windriver.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Linux-sh list" <linux-sh@vger.kernel.org>,
linux-pci <linux-pci@vger.kernel.org>,
"Alexandre Courbot" <gnurou@gmail.com>,
"Pratyush Anand" <pratyush.anand@gmail.com>,
"Michal Simek" <michal.simek@xilinx.com>,
"Kishon Vijay Abraham I" <kishon@ti.com>,
"Murali Karicheri" <m-karicheri2@ti.com>,
"Sören Brinkmann" <soren.brinkmann@xilinx.com>,
"Jason Cooper" <jason@lakedaemon.net>,
"Stephen Warren" <swarren@wwwdotorg.org>,
"Simon Horman" <horms@verge.net.au>,
linux-tegra@vger.kernel.org,
"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"Thomas Petazzoni" <thomas.petazzoni@free-electrons.com>,
"Richard Zhu" <Richard.Zhu@freescale.com>,
rfi@lists.rocketboards.org, "Ley Foon Tan" <lftan@altera.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Lucas Stach" <l.stach@pengutronix.de>
Subject: Re: [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci*
Date: Mon, 14 Dec 2015 09:24:25 +0100 [thread overview]
Message-ID: <20151214082425.GA3766@ulmo.nvidia.com> (raw)
In-Reply-To: <CAMuHMdXr=ErCO3R2LB+wBJh3JSiFkH5q3-FLSTOwdGT87fXz3A@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2553 bytes --]
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@windriver.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.
Thierry
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: thierry.reding@gmail.com (Thierry Reding)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci*
Date: Mon, 14 Dec 2015 09:24:25 +0100 [thread overview]
Message-ID: <20151214082425.GA3766@ulmo.nvidia.com> (raw)
In-Reply-To: <CAMuHMdXr=ErCO3R2LB+wBJh3JSiFkH5q3-FLSTOwdGT87fXz3A@mail.gmail.com>
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@windriver.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.
Thierry
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next prev parent reply other threads:[~2015-12-14 8:24 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-13 1:41 [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci* Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 1:41 ` [PATCH 01/10] drivers/pci: make host/pci-imx6.c driver explicitly non-modular Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-14 8:52 ` Arnd Bergmann
2015-12-14 8:52 ` Arnd Bergmann
2015-12-13 1:41 ` [PATCH 02/10] drivers/pci: make host/pcie-spear13xx.c " Paul Gortmaker
2015-12-13 1:41 ` [PATCH 03/10] drivers/pci: make host/pci-mvebu.c " Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 10:33 ` Thomas Petazzoni
2015-12-13 10:33 ` Thomas Petazzoni
2015-12-14 8:54 ` Arnd Bergmann
2015-12-14 8:54 ` Arnd Bergmann
2015-12-13 1:41 ` [PATCH 04/10] drivers/pci: make host/pci-dra7xx.c " Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 1:41 ` [PATCH 05/10] drivers/pci: make host/pci-rcar-gen2.c " Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 10:59 ` Geert Uytterhoeven
2015-12-13 10:59 ` Geert Uytterhoeven
2015-12-13 18:15 ` Paul Gortmaker
2015-12-13 18:15 ` Paul Gortmaker
2015-12-13 20:37 ` Joe Perches
2015-12-13 20:37 ` Joe Perches
2015-12-14 5:19 ` Simon Horman
2015-12-14 5:19 ` Simon Horman
2015-12-13 1:41 ` [PATCH 06/10] drivers/pci: make host/pci-tegra.c " Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-14 8:15 ` Thierry Reding
2015-12-13 1:41 ` [PATCH 07/10] drivers/pci: make host/pcie-rcar.c " Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 10:58 ` Geert Uytterhoeven
2015-12-13 10:58 ` Geert Uytterhoeven
2015-12-13 18:20 ` Paul Gortmaker
2015-12-13 18:20 ` Paul Gortmaker
2015-12-17 11:32 ` Phil Edworthy
2015-12-17 11:32 ` Phil Edworthy
2015-12-17 11:32 ` Phil Edworthy
2015-12-17 16:06 ` Paul Gortmaker
2015-12-17 16:06 ` Paul Gortmaker
2015-12-14 5:19 ` Simon Horman
2015-12-14 5:19 ` Simon Horman
2015-12-13 1:41 ` [PATCH 08/10] drivers/pci: make host/pcie-xilinx.c " Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-14 7:25 ` Michal Simek
2015-12-14 7:25 ` Michal Simek
2015-12-13 1:41 ` [PATCH 09/10] drivers/pci: make host/pci-keystone.c " Paul Gortmaker
2015-12-13 1:41 ` Paul Gortmaker
2015-12-13 1:41 ` [PATCH 10/10] drivers/pci: make host/pcie-altera.c " Paul Gortmaker
2015-12-14 8:19 ` [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci* Geert Uytterhoeven
2015-12-14 8:19 ` Geert Uytterhoeven
2015-12-14 8:19 ` Geert Uytterhoeven
2015-12-14 8:19 ` Geert Uytterhoeven
2015-12-14 8:24 ` Thierry Reding [this message]
2015-12-14 8:24 ` Thierry Reding
2015-12-14 8:24 ` Thierry Reding
2015-12-14 8:24 ` Thierry Reding
2015-12-14 8:26 ` Michal Simek
2015-12-14 8:26 ` Michal Simek
2015-12-14 8:26 ` Michal Simek
2015-12-14 8:26 ` Michal Simek
2015-12-14 8:33 ` Ley Foon Tan
2015-12-14 8:33 ` Ley Foon Tan
2015-12-14 8:33 ` Ley Foon Tan
2015-12-14 8:33 ` Ley Foon Tan
2015-12-14 9:19 ` Thierry Reding
2015-12-14 9:19 ` Thierry Reding
2015-12-14 9:19 ` Thierry Reding
2015-12-14 9:19 ` Thierry Reding
2015-12-14 10:27 ` Arnd Bergmann
2015-12-14 10:27 ` Arnd Bergmann
2015-12-14 10:27 ` Arnd Bergmann
2015-12-14 10:27 ` Arnd Bergmann
2015-12-15 15:16 ` Paul Gortmaker
2015-12-15 15:16 ` Paul Gortmaker
2015-12-15 15:16 ` Paul Gortmaker
2015-12-15 15:16 ` Paul Gortmaker
2016-01-08 20:31 ` Bjorn Helgaas
2016-01-08 20:31 ` Bjorn Helgaas
2016-01-08 20:31 ` Bjorn Helgaas
2016-01-08 20:31 ` Bjorn Helgaas
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