[PATCH] gpio: gpiolib: make gpio_bus_type const

[PATCH] gpio: gpiolib: make gpio_bus_type const

[Ricardo B. Marliere]

Now that the driver core can properly handle constant struct bus_type,
move the gpio_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>
---
 drivers/gpio/gpiolib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d50a786f8176..24d046268a01 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -63,7 +63,7 @@ static int gpio_bus_match(struct device *dev, struct device_driver *drv)
 	return 1;
 }
 
-static struct bus_type gpio_bus_type = {
+static const struct bus_type gpio_bus_type = {
 	.name = "gpio",
 	.match = gpio_bus_match,
 };

---
base-commit: 3eac8bbed22e940ac1645a884f221bef408f675c
change-id: 20240204-bus_cleanup-gpio-57eea8d32a5a

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

Re: [PATCH] gpio: gpiolib: make gpio_bus_type const

[Bartosz Golaszewski]

On Sun, Feb 4, 2024 at 5:29 PM Ricardo B. Marliere <ricardo@marliere.net> wrote:
>
> Now that the driver core can properly handle constant struct bus_type,
> move the gpio_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>
> ---
>  drivers/gpio/gpiolib.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index d50a786f8176..24d046268a01 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -63,7 +63,7 @@ static int gpio_bus_match(struct device *dev, struct device_driver *drv)
>         return 1;
>  }
>
> -static struct bus_type gpio_bus_type = {
> +static const struct bus_type gpio_bus_type = {
>         .name = "gpio",
>         .match = gpio_bus_match,
>  };
>
> ---
> base-commit: 3eac8bbed22e940ac1645a884f221bef408f675c
> change-id: 20240204-bus_cleanup-gpio-57eea8d32a5a
>
> Best regards,
> --
> Ricardo B. Marliere <ricardo@marliere.net>
>

Ha! Does the same work now for struct device_type?

Because I just sent this:
https://lore.kernel.org/linux-gpio/20240201162758.50733-1-brgl@bgdev.pl/

And maybe I should make it const right away.

Bart

Re: [PATCH] gpio: gpiolib: make gpio_bus_type const

[Ricardo B. Marliere]

Hi Bartosz,

On  4 Feb 19:34, Bartosz Golaszewski wrote:
> On Sun, Feb 4, 2024 at 5:29 PM Ricardo B. Marliere <ricardo@marliere.net> wrote:
> >
> > Now that the driver core can properly handle constant struct bus_type,
> > move the gpio_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>
> > ---
> >  drivers/gpio/gpiolib.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > index d50a786f8176..24d046268a01 100644
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -63,7 +63,7 @@ static int gpio_bus_match(struct device *dev, struct device_driver *drv)
> >         return 1;
> >  }
> >
> > -static struct bus_type gpio_bus_type = {
> > +static const struct bus_type gpio_bus_type = {
> >         .name = "gpio",
> >         .match = gpio_bus_match,
> >  };
> >
> > ---
> > base-commit: 3eac8bbed22e940ac1645a884f221bef408f675c
> > change-id: 20240204-bus_cleanup-gpio-57eea8d32a5a
> >
> > Best regards,
> > --
> > Ricardo B. Marliere <ricardo@marliere.net>
> >
> 
> Ha! Does the same work now for struct device_type?

From a quick grep it seems to be the case, but maybe you should wait for
Greg for confirmation. Also found this:
https://lore.kernel.org/all/1305850262-9575-5-git-send-email-gregkh@suse.de/

Best regards,
-	Ricardo.



> 
> Because I just sent this:
> https://lore.kernel.org/linux-gpio/20240201162758.50733-1-brgl@bgdev.pl/
> 
> And maybe I should make it const right away.
> 
> Bart

Re: [PATCH] gpio: gpiolib: make gpio_bus_type const

[Bartosz Golaszewski]

On Sun, 4 Feb 2024 20:41:52 +0100, "Ricardo B. Marliere"
<ricardo@marliere.net> said:
> Hi Bartosz,
>
> On  4 Feb 19:34, Bartosz Golaszewski wrote:
>> On Sun, Feb 4, 2024 at 5:29 PM Ricardo B. Marliere <ricardo@marliere.net> wrote:
>> >
>> > Now that the driver core can properly handle constant struct bus_type,
>> > move the gpio_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>
>> > ---
>> >  drivers/gpio/gpiolib.c | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
>> > index d50a786f8176..24d046268a01 100644
>> > --- a/drivers/gpio/gpiolib.c
>> > +++ b/drivers/gpio/gpiolib.c
>> > @@ -63,7 +63,7 @@ static int gpio_bus_match(struct device *dev, struct device_driver *drv)
>> >         return 1;
>> >  }
>> >
>> > -static struct bus_type gpio_bus_type = {
>> > +static const struct bus_type gpio_bus_type = {
>> >         .name = "gpio",
>> >         .match = gpio_bus_match,
>> >  };
>> >
>> > ---
>> > base-commit: 3eac8bbed22e940ac1645a884f221bef408f675c
>> > change-id: 20240204-bus_cleanup-gpio-57eea8d32a5a
>> >
>> > Best regards,
>> > --
>> > Ricardo B. Marliere <ricardo@marliere.net>
>> >
>>
>> Ha! Does the same work now for struct device_type?
>
> From a quick grep it seems to be the case, but maybe you should wait for
> Greg for confirmation. Also found this:
> https://lore.kernel.org/all/1305850262-9575-5-git-send-email-gregkh@suse.de/
>
> Best regards,
> -	Ricardo.
>
>
>
>>
>> Because I just sent this:
>> https://lore.kernel.org/linux-gpio/20240201162758.50733-1-brgl@bgdev.pl/
>>
>> And maybe I should make it const right away.
>>
>> Bart
>

Turns out it has been like that for years:

commit aed65af1cc2f6fc9ded5a8158f1405a02cf6d2ff
Author: Stephen Hemminger <shemminger@vyatta.com>
Date:   Mon Mar 28 09:12:52 2011 -0700

    drivers: make device_type const

    The device_type structure does not contain data that changes
    during usage and should be const. This allows devices to declare
    the struct const.

    I have patches to change all the subsystems, but need the infra
    structure change first.

    Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

I queued your patch too.

Bart

Re: [PATCH] gpio: gpiolib: make gpio_bus_type const

[Greg Kroah-Hartman]

On Sun, Feb 04, 2024 at 07:34:43PM +0100, Bartosz Golaszewski wrote:
> On Sun, Feb 4, 2024 at 5:29 PM Ricardo B. Marliere <ricardo@marliere.net> wrote:
> >
> > Now that the driver core can properly handle constant struct bus_type,
> > move the gpio_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>
> > ---
> >  drivers/gpio/gpiolib.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > index d50a786f8176..24d046268a01 100644
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -63,7 +63,7 @@ static int gpio_bus_match(struct device *dev, struct device_driver *drv)
> >         return 1;
> >  }
> >
> > -static struct bus_type gpio_bus_type = {
> > +static const struct bus_type gpio_bus_type = {
> >         .name = "gpio",
> >         .match = gpio_bus_match,
> >  };
> >
> > ---
> > base-commit: 3eac8bbed22e940ac1645a884f221bef408f675c
> > change-id: 20240204-bus_cleanup-gpio-57eea8d32a5a
> >
> > Best regards,
> > --
> > Ricardo B. Marliere <ricardo@marliere.net>
> >
> 
> Ha! Does the same work now for struct device_type?

Very much so, please feel free to do so, that's next on my list of
things to do for the tree.

greg k-h

Re: [PATCH] gpio: gpiolib: make gpio_bus_type const

[Greg Kroah-Hartman]

On Sun, Feb 04, 2024 at 01:29:42PM -0300, Ricardo B. Marliere wrote:
> Now that the driver core can properly handle constant struct bus_type,
> move the gpio_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>

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>