[PATCH 0/4] powerpc: struct bus_type cleanup

[PATCH 0/4] powerpc: struct bus_type cleanup

[Ricardo B. Marliere]

This series is part of an effort to cleanup the users of the driver
core, as can be seen in many recent patches authored by Greg across the
tree (e.g. [1]). Patch 1/4 is a prerequisite to 2/4, but the others have
no dependency. They were built using bootlin's without warnings using
powerpc64le-power8--glibc--stable-2023.11-1 toolchain.

---
[1]: https://lore.kernel.org/lkml/?q=f%3Agregkh%40linuxfoundation.org+s%3A%22make%22+and+s%3A%22const%22

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>

---
Ricardo B. Marliere (4):
      powerpc: vio: move device attributes into a new ifdef
      powerpc: vio: make vio_bus_type const
      powerpc: mpic: make mpic_subsys const
      powerpc: ibmebus: make ibmebus_bus_type const

 arch/powerpc/include/asm/ibmebus.h       |  2 +-
 arch/powerpc/include/asm/mpic.h          |  2 +-
 arch/powerpc/include/asm/vio.h           |  2 +-
 arch/powerpc/platforms/pseries/ibmebus.c |  2 +-
 arch/powerpc/platforms/pseries/vio.c     | 61 ++++++++++++++++++--------------
 arch/powerpc/sysdev/mpic.c               |  2 +-
 6 files changed, 40 insertions(+), 31 deletions(-)
---
base-commit: 41bccc98fb7931d63d03f326a746ac4d429c1dd3
change-id: 20240209-bus_cleanup-powerpc2-498426fccb98

Best regards,
-- 
Ricardo B. Marliere <ricardo@marliere.net>

[PATCH 1/4] powerpc: vio: move device attributes into a new ifdef

[Ricardo B. Marliere]

In order to make the distinction of the vio_bus_type variable based on
CONFIG_PPC_SMLPAR more explicit, move the required structs into a new
ifdef block. This is needed in order to make vio_bus_type const and
because the distinction is made explicit, there is no need to set the
fields within the vio_cmo_sysfs_init function.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
---
 arch/powerpc/platforms/pseries/vio.c | 59 +++++++++++++++++++++---------------
 1 file changed, 34 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
index 2dc9cbc4bcd8..6c58824190a2 100644
--- a/arch/powerpc/platforms/pseries/vio.c
+++ b/arch/powerpc/platforms/pseries/vio.c
@@ -991,18 +991,6 @@ static DEVICE_ATTR_RO(cmo_allocated);
 static DEVICE_ATTR_RW(cmo_desired);
 static DEVICE_ATTR_RW(cmo_allocs_failed);
 
-static struct attribute *vio_cmo_dev_attrs[] = {
-	&dev_attr_name.attr,
-	&dev_attr_devspec.attr,
-	&dev_attr_modalias.attr,
-	&dev_attr_cmo_entitled.attr,
-	&dev_attr_cmo_allocated.attr,
-	&dev_attr_cmo_desired.attr,
-	&dev_attr_cmo_allocs_failed.attr,
-	NULL,
-};
-ATTRIBUTE_GROUPS(vio_cmo_dev);
-
 /* sysfs bus functions and data structures for CMO */
 
 #define viobus_cmo_rd_attr(name)                                        \
@@ -1062,11 +1050,7 @@ static struct attribute *vio_bus_attrs[] = {
 };
 ATTRIBUTE_GROUPS(vio_bus);
 
-static void __init vio_cmo_sysfs_init(void)
-{
-	vio_bus_type.dev_groups = vio_cmo_dev_groups;
-	vio_bus_type.bus_groups = vio_bus_groups;
-}
+static void __init vio_cmo_sysfs_init(void) { }
 #else /* CONFIG_PPC_SMLPAR */
 int vio_cmo_entitlement_update(size_t new_entitlement) { return 0; }
 void vio_cmo_set_dev_desired(struct vio_dev *viodev, size_t desired) {}
@@ -1584,14 +1568,6 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(modalias);
 
-static struct attribute *vio_dev_attrs[] = {
-	&dev_attr_name.attr,
-	&dev_attr_devspec.attr,
-	&dev_attr_modalias.attr,
-	NULL,
-};
-ATTRIBUTE_GROUPS(vio_dev);
-
 void vio_unregister_device(struct vio_dev *viodev)
 {
 	device_unregister(&viodev->dev);
@@ -1626,6 +1602,38 @@ static int vio_hotplug(const struct device *dev, struct kobj_uevent_env *env)
 	return 0;
 }
 
+#ifdef CONFIG_PPC_SMLPAR
+static struct attribute *vio_cmo_dev_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_devspec.attr,
+	&dev_attr_modalias.attr,
+	&dev_attr_cmo_entitled.attr,
+	&dev_attr_cmo_allocated.attr,
+	&dev_attr_cmo_desired.attr,
+	&dev_attr_cmo_allocs_failed.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(vio_cmo_dev);
+
+struct bus_type vio_bus_type = {
+	.name = "vio",
+	.dev_groups = vio_cmo_dev_groups,
+	.bus_groups = vio_bus_groups,
+	.uevent = vio_hotplug,
+	.match = vio_bus_match,
+	.probe = vio_bus_probe,
+	.remove = vio_bus_remove,
+	.shutdown = vio_bus_shutdown,
+};
+#else /* CONFIG_PPC_SMLPAR */
+static struct attribute *vio_dev_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_devspec.attr,
+	&dev_attr_modalias.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(vio_dev);
+
 struct bus_type vio_bus_type = {
 	.name = "vio",
 	.dev_groups = vio_dev_groups,
@@ -1635,6 +1643,7 @@ struct bus_type vio_bus_type = {
 	.remove = vio_bus_remove,
 	.shutdown = vio_bus_shutdown,
 };
+#endif /* CONFIG_PPC_SMLPAR */
 
 /**
  * vio_get_attribute: - get attribute for virtual device

-- 
2.43.0

[PATCH 2/4] powerpc: vio: make vio_bus_type const

[Ricardo B. Marliere]

Now that the driver core can properly handle constant struct bus_type,
move the vio_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
---
 arch/powerpc/include/asm/vio.h       | 2 +-
 arch/powerpc/platforms/pseries/vio.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/vio.h b/arch/powerpc/include/asm/vio.h
index cc9b787627ad..6faf2a931755 100644
--- a/arch/powerpc/include/asm/vio.h
+++ b/arch/powerpc/include/asm/vio.h
@@ -39,7 +39,7 @@
  */
 #define VIO_CMO_MIN_ENT 1562624
 
-extern struct bus_type vio_bus_type;
+extern const struct bus_type vio_bus_type;
 
 struct iommu_table;
 
diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
index 6c58824190a2..90ff85c879bf 100644
--- a/arch/powerpc/platforms/pseries/vio.c
+++ b/arch/powerpc/platforms/pseries/vio.c
@@ -1615,7 +1615,7 @@ static struct attribute *vio_cmo_dev_attrs[] = {
 };
 ATTRIBUTE_GROUPS(vio_cmo_dev);
 
-struct bus_type vio_bus_type = {
+const struct bus_type vio_bus_type = {
 	.name = "vio",
 	.dev_groups = vio_cmo_dev_groups,
 	.bus_groups = vio_bus_groups,
@@ -1634,7 +1634,7 @@ static struct attribute *vio_dev_attrs[] = {
 };
 ATTRIBUTE_GROUPS(vio_dev);
 
-struct bus_type vio_bus_type = {
+const struct bus_type vio_bus_type = {
 	.name = "vio",
 	.dev_groups = vio_dev_groups,
 	.uevent = vio_hotplug,

-- 
2.43.0

[PATCH 3/4] powerpc: mpic: make mpic_subsys const

[Ricardo B. Marliere]

Now that the driver core can properly handle constant struct bus_type,
move the mpic_subsys variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
---
 arch/powerpc/include/asm/mpic.h | 2 +-
 arch/powerpc/sysdev/mpic.c      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/mpic.h b/arch/powerpc/include/asm/mpic.h
index 58353c5bd3fb..0c03a98986cd 100644
--- a/arch/powerpc/include/asm/mpic.h
+++ b/arch/powerpc/include/asm/mpic.h
@@ -336,7 +336,7 @@ struct mpic
 #endif
 };
 
-extern struct bus_type mpic_subsys;
+extern const struct bus_type mpic_subsys;
 
 /*
  * MPIC flags (passed to mpic_alloc)
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index dabbdd356664..d94cf36b0f65 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -49,7 +49,7 @@
 #define DBG(fmt...)
 #endif
 
-struct bus_type mpic_subsys = {
+const struct bus_type mpic_subsys = {
 	.name = "mpic",
 	.dev_name = "mpic",
 };

-- 
2.43.0

[PATCH 4/4] powerpc: ibmebus: make ibmebus_bus_type const

[Ricardo B. Marliere]

Now that the driver core can properly handle constant struct bus_type,
move the ibmebus_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
---
 arch/powerpc/include/asm/ibmebus.h       | 2 +-
 arch/powerpc/platforms/pseries/ibmebus.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/ibmebus.h b/arch/powerpc/include/asm/ibmebus.h
index 6f33253a364a..46fe406f461c 100644
--- a/arch/powerpc/include/asm/ibmebus.h
+++ b/arch/powerpc/include/asm/ibmebus.h
@@ -48,7 +48,7 @@
 
 struct platform_driver;
 
-extern struct bus_type ibmebus_bus_type;
+extern const struct bus_type ibmebus_bus_type;
 
 int ibmebus_register_driver(struct platform_driver *drv);
 void ibmebus_unregister_driver(struct platform_driver *drv);
diff --git a/arch/powerpc/platforms/pseries/ibmebus.c b/arch/powerpc/platforms/pseries/ibmebus.c
index 998e3aff2457..4bb611afaba4 100644
--- a/arch/powerpc/platforms/pseries/ibmebus.c
+++ b/arch/powerpc/platforms/pseries/ibmebus.c
@@ -432,7 +432,7 @@ static int ibmebus_bus_modalias(const struct device *dev, struct kobj_uevent_env
 	return of_device_uevent_modalias(dev, env);
 }
 
-struct bus_type ibmebus_bus_type = {
+const struct bus_type ibmebus_bus_type = {
 	.name      = "ibmebus",
 	.uevent    = ibmebus_bus_modalias,
 	.bus_groups = ibmbus_bus_groups,

-- 
2.43.0

Re: [PATCH 4/4] powerpc: ibmebus: make ibmebus_bus_type const

[kernel test robot]

Hi Ricardo,

kernel test robot noticed the following build errors:

[auto build test ERROR on 41bccc98fb7931d63d03f326a746ac4d429c1dd3]

url:    https://github.com/intel-lab-lkp/linux/commits/Ricardo-B-Marliere/powerpc-vio-move-device-attributes-into-a-new-ifdef/20240210-080925
base:   41bccc98fb7931d63d03f326a746ac4d429c1dd3
patch link:    https://lore.kernel.org/r/20240209-bus_cleanup-powerpc2-v1-4-79a56dcaebb1%40marliere.net
patch subject: [PATCH 4/4] powerpc: ibmebus: make ibmebus_bus_type const
config: powerpc-allmodconfig (https://download.01.org/0day-ci/archive/20240210/202402102142.uphiKeqw-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240210/202402102142.uphiKeqw-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202402102142.uphiKeqw-lkp@intel.com/

All errors (new ones prefixed by >>):

>> arch/powerpc/platforms/pseries/ibmebus.c:58:17: error: conflicting type qualifiers for 'ibmebus_bus_type'
      58 | struct bus_type ibmebus_bus_type;
         |                 ^~~~~~~~~~~~~~~~
   In file included from arch/powerpc/platforms/pseries/ibmebus.c:51:
   arch/powerpc/include/asm/ibmebus.h:51:30: note: previous declaration of 'ibmebus_bus_type' with type 'const struct bus_type'
      51 | extern const struct bus_type ibmebus_bus_type;
         |                              ^~~~~~~~~~~~~~~~
   In file included from arch/powerpc/platforms/pseries/ibmebus.c:40:
   arch/powerpc/platforms/pseries/ibmebus.c:445:15: error: conflicting type qualifiers for 'ibmebus_bus_type'
     445 | EXPORT_SYMBOL(ibmebus_bus_type);
         |               ^~~~~~~~~~~~~~~~
   include/linux/export.h:56:28: note: in definition of macro '__EXPORT_SYMBOL'
      56 |         extern typeof(sym) sym;                                 \
         |                            ^~~
   include/linux/export.h:68:41: note: in expansion of macro '_EXPORT_SYMBOL'
      68 | #define EXPORT_SYMBOL(sym)              _EXPORT_SYMBOL(sym, "")
         |                                         ^~~~~~~~~~~~~~
   arch/powerpc/platforms/pseries/ibmebus.c:445:1: note: in expansion of macro 'EXPORT_SYMBOL'
     445 | EXPORT_SYMBOL(ibmebus_bus_type);
         | ^~~~~~~~~~~~~
   arch/powerpc/platforms/pseries/ibmebus.c:435:23: note: previous definition of 'ibmebus_bus_type' with type 'const struct bus_type'
     435 | const struct bus_type ibmebus_bus_type = {
         |                       ^~~~~~~~~~~~~~~~


vim +/ibmebus_bus_type +58 arch/powerpc/platforms/pseries/ibmebus.c

d7a301033f1990 arch/powerpc/kernel/ibmebus.c Heiko J Schick 2005-11-16  57  
6bccf755ff5324 arch/powerpc/kernel/ibmebus.c Joachim Fenkes 2007-03-09 @58  struct bus_type ibmebus_bus_type;
6bccf755ff5324 arch/powerpc/kernel/ibmebus.c Joachim Fenkes 2007-03-09  59  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 4/4] powerpc: ibmebus: make ibmebus_bus_type const

[kernel test robot]

Hi Ricardo,

kernel test robot noticed the following build errors:

[auto build test ERROR on 41bccc98fb7931d63d03f326a746ac4d429c1dd3]

url:    https://github.com/intel-lab-lkp/linux/commits/Ricardo-B-Marliere/powerpc-vio-move-device-attributes-into-a-new-ifdef/20240210-080925
base:   41bccc98fb7931d63d03f326a746ac4d429c1dd3
patch link:    https://lore.kernel.org/r/20240209-bus_cleanup-powerpc2-v1-4-79a56dcaebb1%40marliere.net
patch subject: [PATCH 4/4] powerpc: ibmebus: make ibmebus_bus_type const
config: powerpc-allyesconfig (https://download.01.org/0day-ci/archive/20240211/202402110615.H1X3DSiC-lkp@intel.com/config)
compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project ac0577177f053ba7e7016e1b7e44cf5932d00b03)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240211/202402110615.H1X3DSiC-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202402110615.H1X3DSiC-lkp@intel.com/

All errors (new ones prefixed by >>):

>> arch/powerpc/platforms/pseries/ibmebus.c:58:17: error: redefinition of 'ibmebus_bus_type' with a different type: 'struct bus_type' vs 'const struct bus_type'
      58 | struct bus_type ibmebus_bus_type;
         |                 ^
   arch/powerpc/include/asm/ibmebus.h:51:30: note: previous declaration is here
      51 | extern const struct bus_type ibmebus_bus_type;
         |                              ^
   arch/powerpc/platforms/pseries/ibmebus.c:134:17: warning: shift count >= width of type [-Wshift-count-overflow]
     134 |         return mask == DMA_BIT_MASK(64);
         |                        ^~~~~~~~~~~~~~~~
   include/linux/dma-mapping.h:77:54: note: expanded from macro 'DMA_BIT_MASK'
      77 | #define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
         |                                                      ^ ~~~
   arch/powerpc/platforms/pseries/ibmebus.c:139:9: warning: shift count >= width of type [-Wshift-count-overflow]
     139 |         return DMA_BIT_MASK(64);
         |                ^~~~~~~~~~~~~~~~
   include/linux/dma-mapping.h:77:54: note: expanded from macro 'DMA_BIT_MASK'
      77 | #define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
         |                                                      ^ ~~~
   2 warnings and 1 error generated.


vim +58 arch/powerpc/platforms/pseries/ibmebus.c

d7a301033f1990 arch/powerpc/kernel/ibmebus.c Heiko J Schick 2005-11-16  57  
6bccf755ff5324 arch/powerpc/kernel/ibmebus.c Joachim Fenkes 2007-03-09 @58  struct bus_type ibmebus_bus_type;
6bccf755ff5324 arch/powerpc/kernel/ibmebus.c Joachim Fenkes 2007-03-09  59  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 0/4] powerpc: struct bus_type cleanup

[Ricardo B. Marliere]

Please disregard this series, I will send a v2.

Thank you,
-	Ricardo.