[PATCH 0/3] soc: avoid module usage in non-modular code

[PATCH 0/3] soc: avoid module usage in non-modular code

[Paul Gortmaker]

This series of commits is a part of a larger project to ensure
people don't reference modular support functions in non-modular
code.  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, gpio ... and we continue to work on other areas.

There are several reasons to not use module support 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.

Two of the changes are essentially source only -- the resuting module
will be binary equivalent.  Only the FSL driver has unused code in
addition to the use of modular macros that get converted.

Note the FSL SOC driver just appeared in linux-next and so this series
won't apply on Linus' master branch.  These commits were applied to
linux-next and build tested there.

Paul.
---

Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Scott Wood <oss@buserror.net>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Yangbo Lu <yangbo.lu@nxp.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-tegra@vger.kernel.org

Paul Gortmaker (3):
  soc: sunxi: make sunxi_sram explicitly non-modular
  soc: tegra: make fuse-tegra explicitly non-modular
  soc: fsl: make guts driver explicitly non-modular

 drivers/soc/fsl/guts.c              | 17 ++---------------
 drivers/soc/sunxi/sunxi_sram.c      |  9 ++-------
 drivers/soc/tegra/fuse/fuse-tegra.c |  4 ++--
 3 files changed, 6 insertions(+), 24 deletions(-)

-- 
2.10.1

[PATCH 1/3] soc: sunxi: make sunxi_sram explicitly non-modular

[Paul Gortmaker]

The Kconfig currently controlling compilation of this code is:

drivers/soc/sunxi/Kconfig:config SUNXI_SRAM
drivers/soc/sunxi/Kconfig:      bool

...meaning that it currently is not being built as a module by anyone.

Lets remove the modular code that is essentially orphaned, so that
when reading the driver there is no doubt it is builtin-only.

Since module_platform_driver() uses the same init level priority as
builtin_platform_driver() the init ordering remains unchanged with
this commit.

Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.

We also delete the MODULE_LICENSE tag etc. since all that information
is already contained at the top of the file in the comments.

Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 drivers/soc/sunxi/sunxi_sram.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/soc/sunxi/sunxi_sram.c b/drivers/soc/sunxi/sunxi_sram.c
index 99e354c8f53f..5e10408a2aef 100644
--- a/drivers/soc/sunxi/sunxi_sram.c
+++ b/drivers/soc/sunxi/sunxi_sram.c
@@ -12,7 +12,7 @@
 
 #include <linux/debugfs.h>
 #include <linux/io.h>
-#include <linux/module.h>
+#include <linux/init.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
@@ -269,7 +269,6 @@ static const struct of_device_id sunxi_sram_dt_match[] = {
 	{ .compatible = "allwinner,sun4i-a10-sram-controller" },
 	{ },
 };
-MODULE_DEVICE_TABLE(of, sunxi_sram_dt_match);
 
 static struct platform_driver sunxi_sram_driver = {
 	.driver = {
@@ -278,8 +277,4 @@ static struct platform_driver sunxi_sram_driver = {
 	},
 	.probe	= sunxi_sram_probe,
 };
-module_platform_driver(sunxi_sram_driver);
-
-MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
-MODULE_DESCRIPTION("Allwinner sunXi SRAM Controller Driver");
-MODULE_LICENSE("GPL");
+builtin_platform_driver(sunxi_sram_driver);
-- 
2.10.1

Re: [PATCH 1/3] soc: sunxi: make sunxi_sram explicitly non-modular

[Maxime Ripard]

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On Sun, Nov 13, 2016 at 02:03:00PM -0500, Paul Gortmaker wrote:
> The Kconfig currently controlling compilation of this code is:
> 
> drivers/soc/sunxi/Kconfig:config SUNXI_SRAM
> drivers/soc/sunxi/Kconfig:      bool
> 
> ...meaning that it currently is not being built as a module by anyone.
> 
> Lets remove the modular code that is essentially orphaned, so that
> when reading the driver there is no doubt it is builtin-only.
> 
> Since module_platform_driver() uses the same init level priority as
> builtin_platform_driver() the init ordering remains unchanged with
> this commit.
> 
> Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
> 
> We also delete the MODULE_LICENSE tag etc. since all that information
> is already contained at the top of the file in the comments.
> 
> Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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[PATCH 2/3] soc: tegra: make fuse-tegra explicitly non-modular

[Paul Gortmaker]

The Makefiles currently controlling compilation of this code is:

drivers/soc/tegra/Makefile:obj-y += fuse/
drivers/soc/tegra/fuse/Makefile:obj-y += fuse-tegra.o

...meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modularity so that when reading the
driver there is no doubt it is builtin-only.

Since module_platform_driver() uses the same init level priority as
builtin_platform_driver() the init ordering remains unchanged with
this commit.

Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: linux-tegra@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 drivers/soc/tegra/fuse/fuse-tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/tegra/fuse/fuse-tegra.c b/drivers/soc/tegra/fuse/fuse-tegra.c
index de2c1bfe28b5..7413f60fa855 100644
--- a/drivers/soc/tegra/fuse/fuse-tegra.c
+++ b/drivers/soc/tegra/fuse/fuse-tegra.c
@@ -18,7 +18,7 @@
 #include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/kobject.h>
-#include <linux/module.h>
+#include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
@@ -168,7 +168,7 @@ static struct platform_driver tegra_fuse_driver = {
 	},
 	.probe = tegra_fuse_probe,
 };
-module_platform_driver(tegra_fuse_driver);
+builtin_platform_driver(tegra_fuse_driver);
 
 bool __init tegra_fuse_read_spare(unsigned int spare)
 {
-- 
2.10.1

Re: [PATCH 2/3] soc: tegra: make fuse-tegra explicitly non-modular

[Thierry Reding]

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On Sun, Nov 13, 2016 at 02:03:01PM -0500, Paul Gortmaker wrote:
> The Makefiles currently controlling compilation of this code is:
> 
> drivers/soc/tegra/Makefile:obj-y += fuse/
> drivers/soc/tegra/fuse/Makefile:obj-y += fuse-tegra.o
> 
> ...meaning that it currently is not being built as a module by anyone.
> 
> Lets remove the couple traces of modularity so that when reading the
> driver there is no doubt it is builtin-only.
> 
> Since module_platform_driver() uses the same init level priority as
> builtin_platform_driver() the init ordering remains unchanged with
> this commit.
> 
> Cc: Stephen Warren <swarren@wwwdotorg.org>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Alexandre Courbot <gnurou@gmail.com>
> Cc: linux-tegra@vger.kernel.org
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> ---
>  drivers/soc/tegra/fuse/fuse-tegra.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied to for-4.12/soc, thanks.

Thierry

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[PATCH 3/3] soc: fsl: make guts driver explicitly non-modular

[Paul Gortmaker]

The Kconfig currently controlling compilation of this code is:

drivers/soc/fsl/Kconfig:config FSL_GUTS
drivers/soc/fsl/Kconfig:        bool

...meaning that it currently is not being built as a module by anyone.

Lets remove the modular code that is essentially orphaned, so that
when reading the driver there is no doubt it is builtin-only.

We explicitly disallow a driver unbind, since that doesn't have a
sensible use case anyway, and it allows us to drop the ".remove"
code for non-modular drivers.

Since the code was already not using module_init, the init ordering
remains unchanged with this commit.

Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.

Cc: Scott Wood <oss@buserror.net>
Cc: Yangbo Lu <yangbo.lu@nxp.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 drivers/soc/fsl/guts.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/soc/fsl/guts.c b/drivers/soc/fsl/guts.c
index 0ac88263c2d7..b4d2fd9263b2 100644
--- a/drivers/soc/fsl/guts.c
+++ b/drivers/soc/fsl/guts.c
@@ -11,7 +11,7 @@
 
 #include <linux/io.h>
 #include <linux/slab.h>
-#include <linux/module.h>
+#include <linux/init.h>
 #include <linux/of_fdt.h>
 #include <linux/sys_soc.h>
 #include <linux/of_address.h>
@@ -180,12 +180,6 @@ static int fsl_guts_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static int fsl_guts_remove(struct platform_device *dev)
-{
-	soc_device_unregister(soc_dev);
-	return 0;
-}
-
 /*
  * Table for matching compatible strings, for device tree
  * guts node, for Freescale QorIQ SOCs.
@@ -212,15 +206,14 @@ static const struct of_device_id fsl_guts_of_match[] = {
 	{ .compatible = "fsl,ls2080a-dcfg", },
 	{}
 };
-MODULE_DEVICE_TABLE(of, fsl_guts_of_match);
 
 static struct platform_driver fsl_guts_driver = {
 	.driver = {
 		.name = "fsl-guts",
+		.suppress_bind_attrs = true,
 		.of_match_table = fsl_guts_of_match,
 	},
 	.probe = fsl_guts_probe,
-	.remove = fsl_guts_remove,
 };
 
 static int __init fsl_guts_init(void)
@@ -228,9 +221,3 @@ static int __init fsl_guts_init(void)
 	return platform_driver_register(&fsl_guts_driver);
 }
 core_initcall(fsl_guts_init);
-
-static void __exit fsl_guts_exit(void)
-{
-	platform_driver_unregister(&fsl_guts_driver);
-}
-module_exit(fsl_guts_exit);
-- 
2.10.1

Re: [PATCH 3/3] soc: fsl: make guts driver explicitly non-modular

[Scott Wood]

On Sun, 2016-11-13 at 14:03 -0500, Paul Gortmaker wrote:
> The Kconfig currently controlling compilation of this code is:
> 
> drivers/soc/fsl/Kconfig:config FSL_GUTS
> drivers/soc/fsl/Kconfig:        bool
> 
> ...meaning that it currently is not being built as a module by anyone.
> 
> Lets remove the modular code that is essentially orphaned, so that
> when reading the driver there is no doubt it is builtin-only.
> 
> We explicitly disallow a driver unbind, since that doesn't have a
> sensible use case anyway, and it allows us to drop the ".remove"
> code for non-modular drivers.
> 
> Since the code was already not using module_init, the init ordering
> remains unchanged with this commit.
> 
> Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
> 
> Cc: Scott Wood <oss@buserror.net>
> Cc: Yangbo Lu <yangbo.lu@nxp.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

Acked-by: Scott Wood <oss@buserror.net>

-Scott