2023-08-10 20:56:49

by Ivan Orlov

Subject: [PATCH] mei: make mei_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the mei_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/misc/mei/main.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 51876da3fd65..902789d3106b 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -27,7 +27,9 @@
#include "mei_dev.h"
#include "client.h"

-static struct class *mei_class;
+static const struct class mei_class = {
+ .name = "mei",
+};
static dev_t mei_devt;
#define MEI_MAX_DEVS MINORMASK
static DEFINE_MUTEX(mei_minor_lock);
@@ -1115,7 +1117,7 @@ void mei_set_devstate(struct mei_device *dev, enum mei_dev_state state)

dev->dev_state = state;

- clsdev = class_find_device_by_devt(mei_class, dev->cdev.dev);
+ clsdev = class_find_device_by_devt(&mei_class, dev->cdev.dev);
if (clsdev) {
sysfs_notify(&clsdev->kobj, NULL, "dev_state");
put_device(clsdev);
@@ -1232,7 +1234,7 @@ int mei_register(struct mei_device *dev, struct device *parent)
goto err_dev_add;
}

- clsdev = device_create_with_groups(mei_class, parent, devno,
+ clsdev = device_create_with_groups(&mei_class, parent, devno,
dev, mei_groups,
"mei%d", dev->minor);

@@ -1264,7 +1266,7 @@ void mei_deregister(struct mei_device *dev)

mei_dbgfs_deregister(dev);

- device_destroy(mei_class, devno);
+ device_destroy(&mei_class, devno);

mei_minor_free(dev);
}
@@ -1274,10 +1276,9 @@ static int __init mei_init(void)
{
int ret;

- mei_class = class_create("mei");
- if (IS_ERR(mei_class)) {
+ ret = class_register(&mei_class);
+ if (ret) {
pr_err("couldn't create class\n");
- ret = PTR_ERR(mei_class);
goto err;
}

@@ -1298,7 +1299,7 @@ static int __init mei_init(void)
err_chrdev:
unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
err_class:
- class_destroy(mei_class);
+ class_unregister(&mei_class);
err:
return ret;
}
@@ -1306,7 +1307,7 @@ static int __init mei_init(void)
static void __exit mei_exit(void)
{
unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
- class_destroy(mei_class);
+ class_unregister(&mei_class);
mei_cl_bus_exit();
}

--
2.34.1

2023-08-11 20:24:32

by Ivan Orlov

Subject: Re: [PATCH] mei: make mei_class a static const structure

On 8/11/23 23:40, Greg KH wrote:
> On Thu, Aug 10, 2023 at 11:46:52PM +0400, Ivan Orlov wrote:
>> Now that the driver core allows for struct class to be in read-only
>> memory, move the mei_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/misc/mei/main.c | 19 ++++++++++---------
>> 1 file changed, 10 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
>> index 51876da3fd65..902789d3106b 100644
>> --- a/drivers/misc/mei/main.c
>> +++ b/drivers/misc/mei/main.c
>> @@ -27,7 +27,9 @@
>> #include "mei_dev.h"
>> #include "client.h"
>>
>> -static struct class *mei_class;
>> +static const struct class mei_class = {
>> + .name = "mei",
>> +};
>> static dev_t mei_devt;
>
> Extra line after the new structure?
>
>> #define MEI_MAX_DEVS MINORMASK
>> static DEFINE_MUTEX(mei_minor_lock);
>> @@ -1115,7 +1117,7 @@ void mei_set_devstate(struct mei_device *dev, enum mei_dev_state state)
>>
>> dev->dev_state = state;
>>
>> - clsdev = class_find_device_by_devt(mei_class, dev->cdev.dev);
>> + clsdev = class_find_device_by_devt(&mei_class, dev->cdev.dev);
>> if (clsdev) {
>> sysfs_notify(&clsdev->kobj, NULL, "dev_state");
>> put_device(clsdev);
>> @@ -1232,7 +1234,7 @@ int mei_register(struct mei_device *dev, struct device *parent)
>> goto err_dev_add;
>> }
>>
>> - clsdev = device_create_with_groups(mei_class, parent, devno,
>> + clsdev = device_create_with_groups(&mei_class, parent, devno,
>> dev, mei_groups,
>> "mei%d", dev->minor);
>>
>> @@ -1264,7 +1266,7 @@ void mei_deregister(struct mei_device *dev)
>>
>> mei_dbgfs_deregister(dev);
>>
>> - device_destroy(mei_class, devno);
>> + device_destroy(&mei_class, devno);
>>
>> mei_minor_free(dev);
>> }
>> @@ -1274,10 +1276,9 @@ static int __init mei_init(void)
>> {
>> int ret;
>>
>> - mei_class = class_create("mei");
>> - if (IS_ERR(mei_class)) {
>> + ret = class_register(&mei_class);
>> + if (ret) {
>> pr_err("couldn't create class\n");
>
> This message doesn't make sense anymore. No need for it either, just
> remove it and do a simple:
> return err;
> here instead.
>
> thanks,
>
> greg k-h


Hi Greg,

Thank you for the review, I'll make the suggested changes and send you
the V2.

--
Kind regards,
Ivan Orlov

2023-08-11 20:50:08

by Greg Kroah-Hartman

Subject: Re: [PATCH] mei: make mei_class a static const structure

On Thu, Aug 10, 2023 at 11:46:52PM +0400, Ivan Orlov wrote:
> Now that the driver core allows for struct class to be in read-only
> memory, move the mei_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/misc/mei/main.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
> index 51876da3fd65..902789d3106b 100644
> --- a/drivers/misc/mei/main.c
> +++ b/drivers/misc/mei/main.c
> @@ -27,7 +27,9 @@
> #include "mei_dev.h"
> #include "client.h"
>
> -static struct class *mei_class;
> +static const struct class mei_class = {
> + .name = "mei",
> +};
> static dev_t mei_devt;

Extra line after the new structure?

> #define MEI_MAX_DEVS MINORMASK
> static DEFINE_MUTEX(mei_minor_lock);
> @@ -1115,7 +1117,7 @@ void mei_set_devstate(struct mei_device *dev, enum mei_dev_state state)
>
> dev->dev_state = state;
>
> - clsdev = class_find_device_by_devt(mei_class, dev->cdev.dev);
> + clsdev = class_find_device_by_devt(&mei_class, dev->cdev.dev);
> if (clsdev) {
> sysfs_notify(&clsdev->kobj, NULL, "dev_state");
> put_device(clsdev);
> @@ -1232,7 +1234,7 @@ int mei_register(struct mei_device *dev, struct device *parent)
> goto err_dev_add;
> }
>
> - clsdev = device_create_with_groups(mei_class, parent, devno,
> + clsdev = device_create_with_groups(&mei_class, parent, devno,
> dev, mei_groups,
> "mei%d", dev->minor);
>
> @@ -1264,7 +1266,7 @@ void mei_deregister(struct mei_device *dev)
>
> mei_dbgfs_deregister(dev);
>
> - device_destroy(mei_class, devno);
> + device_destroy(&mei_class, devno);
>
> mei_minor_free(dev);
> }
> @@ -1274,10 +1276,9 @@ static int __init mei_init(void)
> {
> int ret;
>
> - mei_class = class_create("mei");
> - if (IS_ERR(mei_class)) {
> + ret = class_register(&mei_class);
> + if (ret) {
> pr_err("couldn't create class\n");

This message doesn't make sense anymore. No need for it either, just
remove it and do a simple:
return err;
here instead.

thanks,

greg k-h