linux-kernel - Re: [PATCH 1/2] ACPI: platform_profile: Add devm_platform_profile

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Message-ID: <w2pu2epu4ly5s3rmvuh3vcnsm5vyonxbcvz3po57dwiikfpdsd@x3uldtjpzwmr>
Date: Mon, 23 Dec 2024 00:54:54 -0500
From: Kurt Borja <kuurtb@...il.com>
To: Armin Wolf <W_Armin@....de>
Cc: platform-driver-x86@...r.kernel.org, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, Mark Pearson <mpearson-lenovo@...ebb.ca>, 
	Mario Limonciello <mario.limonciello@....com>, Hans de Goede <hdegoede@...hat.com>, 
	Gergo Koteles <soyer@....hu>, linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] ACPI: platform_profile: Add
 devm_platform_profile_register()

On Sun, Dec 22, 2024 at 11:09:44PM +0100, Armin Wolf wrote:
> Am 21.12.24 um 08:08 schrieb Kurt Borja:
> 
> > Platform profile's lifetime is usually tied to a device's lifetime,
> > therefore add a device managed version of platform_profile_register().
> > 
> > Signed-off-by: Kurt Borja <kuurtb@...il.com>
> > ---
> >   drivers/acpi/platform_profile.c  | 27 +++++++++++++++++++++++++++
> >   include/linux/platform_profile.h |  2 +-
> >   2 files changed, 28 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
> > index 75a1415190ac..d0c88decef8b 100644
> > --- a/drivers/acpi/platform_profile.c
> > +++ b/drivers/acpi/platform_profile.c
> > @@ -519,6 +519,33 @@ int platform_profile_remove(struct platform_profile_handler *pprof)
> >   }
> >   EXPORT_SYMBOL_GPL(platform_profile_remove);
> > 
> > +static void devm_platform_profile_release(struct device *dev, void *res)
> > +{
> > +	platform_profile_remove(*(struct platform_profile_handler **) res);
> 
> Please introduce a local variable instead of using a convoluted cast like this.

Sure!

> 
> > +}
> > +
> > +int devm_platform_profile_register(struct platform_profile_handler *pprof)
> > +{
> > +	struct platform_profile_handler **dr;
> > +	int ret;
> > +
> > +	dr = devres_alloc(devm_platform_profile_release, sizeof(*dr), GFP_KERNEL);
> > +	if (!dr)
> > +		return -ENOMEM;
> 
> Maybe it would make sense to turn dr into a normal pointer? AFAIK there is no benefit in
> having another pointer if we can just use the original pointer.

Please, tell me if I'm wrong. devres_alloc returns a pointer to the data
buffer of the devres struct and the handler is already allocated by the
driver, so the only way to store *pprof is to have dr be **.

> 
> Thanks,
> Armin Wolf
> 
> > +
> > +	ret = platform_profile_register(pprof);
> > +	if (ret) {
> > +		devres_free(dr);
> > +		return ret;
> > +	}
> > +
> > +	*dr = pprof;
> > +	devres_add(pprof->dev, dr);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(devm_platform_profile_register);
> > +
> >   static int __init platform_profile_init(void)
> >   {
> >   	int err;
> > diff --git a/include/linux/platform_profile.h b/include/linux/platform_profile.h
> > index 0682bb4c57e5..d8114435865b 100644
> > --- a/include/linux/platform_profile.h
> > +++ b/include/linux/platform_profile.h
> > @@ -41,7 +41,7 @@ struct platform_profile_handler {
> > 
> >   int platform_profile_register(struct platform_profile_handler *pprof);
> >   int platform_profile_remove(struct platform_profile_handler *pprof);
> > +int devm_platform_profile_register(struct platform_profile_handler *pprof);
> >   int platform_profile_cycle(void);
> >   void platform_profile_notify(struct platform_profile_handler *pprof);
> > -

BTW, I just saw this -. I'll remove it on v2.

> >   #endif  /*_PLATFORM_PROFILE_H_*/