2023-08-11 07:47:04

by Ivan Orlov

Subject: [PATCH v2 3/3] fpga: region: make fpga_region_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the fpga_region_class structure to be declared at build
time placing it into read-only memory, instead of having to be
dynamically allocated at boot time.

Suggested-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Ivan Orlov <[email protected]>
---
drivers/fpga/fpga-region.c | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
index ccf6fdab1360..6abd8a154047 100644
--- a/drivers/fpga/fpga-region.c
+++ b/drivers/fpga/fpga-region.c
@@ -16,7 +16,7 @@
#include <linux/spinlock.h>

static DEFINE_IDA(fpga_region_ida);
-static struct class *fpga_region_class;
+static const struct class fpga_region_class;

struct fpga_region *
fpga_region_class_find(struct device *start, const void *data,
@@ -24,7 +24,7 @@ fpga_region_class_find(struct device *start, const void *data,
{
struct device *dev;

- dev = class_find_device(fpga_region_class, start, data, match);
+ dev = class_find_device(&fpga_region_class, start, data, match);
if (!dev)
return NULL;

@@ -216,7 +216,7 @@ fpga_region_register_full(struct device *parent, const struct fpga_region_info *
mutex_init(&region->mutex);
INIT_LIST_HEAD(&region->bridge_list);

- region->dev.class = fpga_region_class;
+ region->dev.class = &fpga_region_class;
region->dev.parent = parent;
region->dev.of_node = parent->of_node;
region->dev.id = id;
@@ -287,25 +287,24 @@ static void fpga_region_dev_release(struct device *dev)
kfree(region);
}

+static const struct class fpga_region_class = {
+ .name = "fpga_region",
+ .dev_groups = fpga_region_groups,
+ .dev_release = fpga_region_dev_release,
+};
+
/**
* fpga_region_init - init function for fpga_region class
* Creates the fpga_region class and registers a reconfig notifier.
*/
static int __init fpga_region_init(void)
{
- fpga_region_class = class_create("fpga_region");
- if (IS_ERR(fpga_region_class))
- return PTR_ERR(fpga_region_class);
-
- fpga_region_class->dev_groups = fpga_region_groups;
- fpga_region_class->dev_release = fpga_region_dev_release;
-
- return 0;
+ return class_register(&fpga_region_class);
}

static void __exit fpga_region_exit(void)
{
- class_destroy(fpga_region_class);
+ class_unregister(&fpga_region_class);
ida_destroy(&fpga_region_ida);
}

--
2.34.1

2023-08-11 10:11:23

by Ivan Orlov

Subject: Re: [PATCH v2 3/3] fpga: region: make fpga_region_class a static const structure

On 8/11/23 11:30, Ivan Orlov wrote:
> Now that the driver core allows for struct class to be in read-only
> memory, move the fpga_region_class structure to be declared at build
> time placing it into read-only memory, instead of having to be
> dynamically allocated at boot time.
>
> Suggested-by: Greg Kroah-Hartman <[email protected]>
> Signed-off-by: Ivan Orlov <[email protected]>
> ---
> drivers/fpga/fpga-region.c | 23 +++++++++++------------
> 1 file changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
> index ccf6fdab1360..6abd8a154047 100644
> --- a/drivers/fpga/fpga-region.c
> +++ b/drivers/fpga/fpga-region.c
> @@ -16,7 +16,7 @@
> #include <linux/spinlock.h>
>
> static DEFINE_IDA(fpga_region_ida);
> -static struct class *fpga_region_class;
> +static const struct class fpga_region_class;
>
> struct fpga_region *
> fpga_region_class_find(struct device *start, const void *data,
> @@ -24,7 +24,7 @@ fpga_region_class_find(struct device *start, const void *data,
> {
> struct device *dev;
>
> - dev = class_find_device(fpga_region_class, start, data, match);
> + dev = class_find_device(&fpga_region_class, start, data, match);
> if (!dev)
> return NULL;
>
> @@ -216,7 +216,7 @@ fpga_region_register_full(struct device *parent, const struct fpga_region_info *
> mutex_init(&region->mutex);
> INIT_LIST_HEAD(&region->bridge_list);
>
> - region->dev.class = fpga_region_class;
> + region->dev.class = &fpga_region_class;
> region->dev.parent = parent;
> region->dev.of_node = parent->of_node;
> region->dev.id = id;
> @@ -287,25 +287,24 @@ static void fpga_region_dev_release(struct device *dev)
> kfree(region);
> }
>
> +static const struct class fpga_region_class = {
> + .name = "fpga_region",
> + .dev_groups = fpga_region_groups,
> + .dev_release = fpga_region_dev_release,
> +};
> +
> /**
> * fpga_region_init - init function for fpga_region class
> * Creates the fpga_region class and registers a reconfig notifier.
> */
> static int __init fpga_region_init(void)
> {
> - fpga_region_class = class_create("fpga_region");
> - if (IS_ERR(fpga_region_class))
> - return PTR_ERR(fpga_region_class);
> -
> - fpga_region_class->dev_groups = fpga_region_groups;
> - fpga_region_class->dev_release = fpga_region_dev_release;
> -
> - return 0;
> + return class_register(&fpga_region_class);
> }
>
> static void __exit fpga_region_exit(void)
> {
> - class_destroy(fpga_region_class);
> + class_unregister(&fpga_region_class);
> ida_destroy(&fpga_region_ida);
> }
>
And I forgot the changelog here.

V1 -> V2:
- Add forward declaration of fpga_region_class
- Move definition of fpga_region_class to more logical place