[PATCH] platform/x86: panasonic-laptop: simplify allocation of sinf

[PATCH] platform/x86: panasonic-laptop: simplify allocation of sinf

[Rosen Penev]

Change to a flexible array member to allocate once instead of twice.

Allows using __counted_by for extra runtime analysis. Move the counting
variable assignment to right after allocation as required by
__counted_by.

Remove + 1 to allocation. It's already done in the previous line.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/platform/x86/panasonic-laptop.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index d923ddaa4849..4d663fffbcc8 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -248,11 +248,11 @@ struct pcc_acpi {
 	int			ac_brightness;
 	int			dc_brightness;
 	int			current_brightness;
-	u32			*sinf;
 	struct acpi_device	*device;
 	struct input_dev	*input_dev;
 	struct backlight_device	*backlight;
 	struct platform_device	*platform;
+	u32			sinf[] __counted_by(num_sifr);
 };
 
 /*
@@ -1017,21 +1017,15 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	 */
 	num_sifr++;
 
-	pcc = kzalloc_obj(struct pcc_acpi);
+	pcc = kzalloc_flex(*pcc, sinf, num_sifr);
 	if (!pcc) {
 		pr_err("Couldn't allocate mem for pcc");
 		return -ENOMEM;
 	}
 
-	pcc->sinf = kcalloc(num_sifr + 1, sizeof(u32), GFP_KERNEL);
-	if (!pcc->sinf) {
-		result = -ENOMEM;
-		goto out_hotkey;
-	}
-
+	pcc->num_sifr = num_sifr;
 	pcc->device = device;
 	pcc->handle = device->handle;
-	pcc->num_sifr = num_sifr;
 	device->driver_data = pcc;
 	strscpy(acpi_device_name(device), ACPI_PCC_DEVICE_NAME);
 	strscpy(acpi_device_class(device), ACPI_PCC_CLASS);
@@ -1039,7 +1033,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	result = acpi_pcc_init_input(pcc);
 	if (result) {
 		pr_err("Error installing keyinput handler\n");
-		goto out_sinf;
+		goto out_hotkey;
 	}
 
 	if (!acpi_pcc_retrieve_biosdata(pcc)) {
@@ -1111,8 +1105,6 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	backlight_device_unregister(pcc->backlight);
 out_input:
 	input_unregister_device(pcc->input_dev);
-out_sinf:
-	kfree(pcc->sinf);
 out_hotkey:
 	kfree(pcc);
 
@@ -1140,7 +1132,6 @@ static void acpi_pcc_hotkey_remove(struct acpi_device *device)
 
 	input_unregister_device(pcc->input_dev);
 
-	kfree(pcc->sinf);
 	kfree(pcc);
 }
 
-- 
2.53.0

Re: [PATCH] platform/x86: panasonic-laptop: simplify allocation of sinf

[Kees Cook]

On Thu, Mar 19, 2026 at 05:49:28PM -0700, Rosen Penev wrote:
> Change to a flexible array member to allocate once instead of twice.
> 
> Allows using __counted_by for extra runtime analysis. Move the counting
> variable assignment to right after allocation as required by
> __counted_by.
> 
> Remove + 1 to allocation. It's already done in the previous line.

Are you sure this is an accidental +1? I see the "num_sifr++" that
happens earlier, but it's not immediately clear why either that or the
+1 in the original allocation are needed. I'd like to understand why
either/both are/aren't needed.

-Kees

> 
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>  drivers/platform/x86/panasonic-laptop.c | 17 ++++-------------
>  1 file changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
> index d923ddaa4849..4d663fffbcc8 100644
> --- a/drivers/platform/x86/panasonic-laptop.c
> +++ b/drivers/platform/x86/panasonic-laptop.c
> @@ -248,11 +248,11 @@ struct pcc_acpi {
>  	int			ac_brightness;
>  	int			dc_brightness;
>  	int			current_brightness;
> -	u32			*sinf;
>  	struct acpi_device	*device;
>  	struct input_dev	*input_dev;
>  	struct backlight_device	*backlight;
>  	struct platform_device	*platform;
> +	u32			sinf[] __counted_by(num_sifr);
>  };
>  
>  /*
> @@ -1017,21 +1017,15 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
>  	 */
>  	num_sifr++;
>  
> -	pcc = kzalloc_obj(struct pcc_acpi);
> +	pcc = kzalloc_flex(*pcc, sinf, num_sifr);
>  	if (!pcc) {
>  		pr_err("Couldn't allocate mem for pcc");
>  		return -ENOMEM;
>  	}
>  
> -	pcc->sinf = kcalloc(num_sifr + 1, sizeof(u32), GFP_KERNEL);
> -	if (!pcc->sinf) {
> -		result = -ENOMEM;
> -		goto out_hotkey;
> -	}
> -
> +	pcc->num_sifr = num_sifr;
>  	pcc->device = device;
>  	pcc->handle = device->handle;
> -	pcc->num_sifr = num_sifr;
>  	device->driver_data = pcc;
>  	strscpy(acpi_device_name(device), ACPI_PCC_DEVICE_NAME);
>  	strscpy(acpi_device_class(device), ACPI_PCC_CLASS);
> @@ -1039,7 +1033,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
>  	result = acpi_pcc_init_input(pcc);
>  	if (result) {
>  		pr_err("Error installing keyinput handler\n");
> -		goto out_sinf;
> +		goto out_hotkey;
>  	}
>  
>  	if (!acpi_pcc_retrieve_biosdata(pcc)) {
> @@ -1111,8 +1105,6 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
>  	backlight_device_unregister(pcc->backlight);
>  out_input:
>  	input_unregister_device(pcc->input_dev);
> -out_sinf:
> -	kfree(pcc->sinf);
>  out_hotkey:
>  	kfree(pcc);
>  
> @@ -1140,7 +1132,6 @@ static void acpi_pcc_hotkey_remove(struct acpi_device *device)
>  
>  	input_unregister_device(pcc->input_dev);
>  
> -	kfree(pcc->sinf);
>  	kfree(pcc);
>  }
>  
> -- 
> 2.53.0
> 

-- 
Kees Cook

Re: [PATCH] platform/x86: panasonic-laptop: simplify allocation of sinf

[Rosen Penev]

On Fri, Mar 20, 2026 at 11:32 AM Kees Cook <kees@kernel.org> wrote:
>
> On Thu, Mar 19, 2026 at 05:49:28PM -0700, Rosen Penev wrote:
> > Change to a flexible array member to allocate once instead of twice.
> >
> > Allows using __counted_by for extra runtime analysis. Move the counting
> > variable assignment to right after allocation as required by
> > __counted_by.
> >
> > Remove + 1 to allocation. It's already done in the previous line.
>
> Are you sure this is an accidental +1? I see the "num_sifr++" that
> happens earlier, but it's not immediately clear why either that or the
> +1 in the original allocation are needed. I'd like to understand why
> either/both are/aren't needed.
Looks like a rebasing mistake to me honestly.
>
> -Kees
>
> >
> > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> > ---
> >  drivers/platform/x86/panasonic-laptop.c | 17 ++++-------------
> >  1 file changed, 4 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
> > index d923ddaa4849..4d663fffbcc8 100644
> > --- a/drivers/platform/x86/panasonic-laptop.c
> > +++ b/drivers/platform/x86/panasonic-laptop.c
> > @@ -248,11 +248,11 @@ struct pcc_acpi {
> >       int                     ac_brightness;
> >       int                     dc_brightness;
> >       int                     current_brightness;
> > -     u32                     *sinf;
> >       struct acpi_device      *device;
> >       struct input_dev        *input_dev;
> >       struct backlight_device *backlight;
> >       struct platform_device  *platform;
> > +     u32                     sinf[] __counted_by(num_sifr);
> >  };
> >
> >  /*
> > @@ -1017,21 +1017,15 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
> >        */
> >       num_sifr++;
> >
> > -     pcc = kzalloc_obj(struct pcc_acpi);
> > +     pcc = kzalloc_flex(*pcc, sinf, num_sifr);
> >       if (!pcc) {
> >               pr_err("Couldn't allocate mem for pcc");
> >               return -ENOMEM;
> >       }
> >
> > -     pcc->sinf = kcalloc(num_sifr + 1, sizeof(u32), GFP_KERNEL);
> > -     if (!pcc->sinf) {
> > -             result = -ENOMEM;
> > -             goto out_hotkey;
> > -     }
> > -
> > +     pcc->num_sifr = num_sifr;
> >       pcc->device = device;
> >       pcc->handle = device->handle;
> > -     pcc->num_sifr = num_sifr;
> >       device->driver_data = pcc;
> >       strscpy(acpi_device_name(device), ACPI_PCC_DEVICE_NAME);
> >       strscpy(acpi_device_class(device), ACPI_PCC_CLASS);
> > @@ -1039,7 +1033,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
> >       result = acpi_pcc_init_input(pcc);
> >       if (result) {
> >               pr_err("Error installing keyinput handler\n");
> > -             goto out_sinf;
> > +             goto out_hotkey;
> >       }
> >
> >       if (!acpi_pcc_retrieve_biosdata(pcc)) {
> > @@ -1111,8 +1105,6 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
> >       backlight_device_unregister(pcc->backlight);
> >  out_input:
> >       input_unregister_device(pcc->input_dev);
> > -out_sinf:
> > -     kfree(pcc->sinf);
> >  out_hotkey:
> >       kfree(pcc);
> >
> > @@ -1140,7 +1132,6 @@ static void acpi_pcc_hotkey_remove(struct acpi_device *device)
> >
> >       input_unregister_device(pcc->input_dev);
> >
> > -     kfree(pcc->sinf);
> >       kfree(pcc);
> >  }
> >
> > --
> > 2.53.0
> >
>
> --
> Kees Cook

Re: [PATCH] platform/x86: panasonic-laptop: simplify allocation of sinf

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 1297 bytes --]

On Fri, 20 Mar 2026, Rosen Penev wrote:
> On Fri, Mar 20, 2026 at 11:32 AM Kees Cook <kees@kernel.org> wrote:
> >
> > On Thu, Mar 19, 2026 at 05:49:28PM -0700, Rosen Penev wrote:
> > > Change to a flexible array member to allocate once instead of twice.
> > >
> > > Allows using __counted_by for extra runtime analysis. Move the counting
> > > variable assignment to right after allocation as required by
> > > __counted_by.
> > >
> > > Remove + 1 to allocation. It's already done in the previous line.
> >
> > Are you sure this is an accidental +1? I see the "num_sifr++" that
> > happens earlier, but it's not immediately clear why either that or the
> > +1 in the original allocation are needed. I'd like to understand why
> > either/both are/aren't needed.

There's a comment right before the increment:

        /*
         * Some DSDT-s have an off-by-one bug where the SINF package count is
         * one higher than the SQTY reported value, allocate 1 entry extra.
         */
        num_sifr++;

..l.which comes from 33297cef3101 ("platform/x86: panasonic-laptop: 
Allocate 1 entry extra in the sinf array").

So I don't know why you said it's not clear why it's there.

> Looks like a rebasing mistake to me honestly.

In which commit?


-- 
 i.

Re: [PATCH] platform/x86: panasonic-laptop: simplify allocation of sinf

[Rosen Penev]

On Mon, Mar 23, 2026 at 2:13 AM Ilpo Järvinen
<ilpo.jarvinen@linux.intel.com> wrote:
>
> On Fri, 20 Mar 2026, Rosen Penev wrote:
> > On Fri, Mar 20, 2026 at 11:32 AM Kees Cook <kees@kernel.org> wrote:
> > >
> > > On Thu, Mar 19, 2026 at 05:49:28PM -0700, Rosen Penev wrote:
> > > > Change to a flexible array member to allocate once instead of twice.
> > > >
> > > > Allows using __counted_by for extra runtime analysis. Move the counting
> > > > variable assignment to right after allocation as required by
> > > > __counted_by.
> > > >
> > > > Remove + 1 to allocation. It's already done in the previous line.
> > >
> > > Are you sure this is an accidental +1? I see the "num_sifr++" that
> > > happens earlier, but it's not immediately clear why either that or the
> > > +1 in the original allocation are needed. I'd like to understand why
> > > either/both are/aren't needed.
>
> There's a comment right before the increment:
>
>         /*
>          * Some DSDT-s have an off-by-one bug where the SINF package count is
>          * one higher than the SQTY reported value, allocate 1 entry extra.
>          */
>         num_sifr++;
>
> ..l.which comes from 33297cef3101 ("platform/x86: panasonic-laptop:
> Allocate 1 entry extra in the sinf array").
>
> So I don't know why you said it's not clear why it's there.
>
> > Looks like a rebasing mistake to me honestly.
>
> In which commit?
None in particular. Probably just a mistake.
>
>
> --
>  i.