[3/4] gpio: Remove VLA from xra1403 driver

Message ID 20180310001021.6437-4-labbott@redhat.com
State New
Headers show
Series
  • VLA removal from the GPIO subsystem
Related show

Commit Message

Laura Abbott March 10, 2018, 12:10 a.m.
The new challenge is to remove VLAs from the kernel
(see https://lkml.org/lkml/2018/3/7/621)

This patch replaces a VLA with an appropriate call to kmalloc_array.

Signed-off-by: Laura Abbott <labbott@redhat.com>
---
 drivers/gpio/gpio-xra1403.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Nandor Han March 12, 2018, 6:06 a.m. | #1
On 10/03/18 02:10, Laura Abbott wrote:
> 
> The new challenge is to remove VLAs from the kernel
> (see https://lkml.org/lkml/2018/3/7/621)
> 
> This patch replaces a VLA with an appropriate call to kmalloc_array.
> 
> Signed-off-by: Laura Abbott <labbott@redhat.com>
> ---

This looks good to me.
Reviewed-by: Nandor Han <nandor.han@ge.com>

Nandor

>   drivers/gpio/gpio-xra1403.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpio-xra1403.c b/drivers/gpio/gpio-xra1403.c
> index 0230e4b7a2fb..8d4c8e99b251 100644
> --- a/drivers/gpio/gpio-xra1403.c
> +++ b/drivers/gpio/gpio-xra1403.c
> @@ -126,11 +126,16 @@ static void xra1403_dbg_show(struct seq_file *s, struct gpio_chip *chip)
>   {
>   	int reg;
>   	struct xra1403 *xra = gpiochip_get_data(chip);
> -	int value[xra1403_regmap_cfg.max_register];
> +	int *value;
>   	int i;
>   	unsigned int gcr;
>   	unsigned int gsr;
>   
> +	value = kmalloc_array(xra1403_regmap_cfg.max_register, sizeof(*value),
> +				GFP_KERNEL);
> +	if (!value)
> +		return;
> +
>   	seq_puts(s, "xra reg:");
>   	for (reg = 0; reg <= xra1403_regmap_cfg.max_register; reg++)
>   		seq_printf(s, " %2.2x", reg);
> @@ -154,6 +159,7 @@ static void xra1403_dbg_show(struct seq_file *s, struct gpio_chip *chip)
>   			   (gcr & BIT(i)) ? "in" : "out",
>   			   (gsr & BIT(i)) ? "hi" : "lo");
>   	}
> +	kfree(value);
>   }
>   #else
>   #define xra1403_dbg_show NULL
> 

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Linus Walleij March 26, 2018, 9:09 a.m. | #2
On Sat, Mar 10, 2018 at 1:10 AM, Laura Abbott <labbott@redhat.com> wrote:

> The new challenge is to remove VLAs from the kernel
> (see https://lkml.org/lkml/2018/3/7/621)
>
> This patch replaces a VLA with an appropriate call to kmalloc_array.
>
> Signed-off-by: Laura Abbott <labbott@redhat.com>

Patch applied with Nandor's review tag.

Yours,
Linus Walleij
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Geert Uytterhoeven March 28, 2018, 7:27 a.m. | #3
Hi Laura,

On Sat, Mar 10, 2018 at 1:10 AM, Laura Abbott <labbott@redhat.com> wrote:
> The new challenge is to remove VLAs from the kernel
> (see https://lkml.org/lkml/2018/3/7/621)
>
> This patch replaces a VLA with an appropriate call to kmalloc_array.
>
> Signed-off-by: Laura Abbott <labbott@redhat.com>

Thanks for your patch!

> --- a/drivers/gpio/gpio-xra1403.c
> +++ b/drivers/gpio/gpio-xra1403.c
> @@ -126,11 +126,16 @@ static void xra1403_dbg_show(struct seq_file *s, struct gpio_chip *chip)
>  {
>         int reg;
>         struct xra1403 *xra = gpiochip_get_data(chip);
> -       int value[xra1403_regmap_cfg.max_register];

Apparently xra1403_regmap_cfg.max_register is always 0x15?

What about adding

        #define XRA_LAST 15

at the top, and replacing both "XRA_IFR | 0x01" and
xra1403_regmap_cfg.max_register by XRA_LAST instead?
That would avoid doing yet another memory allocation over and over.

Gr{oetje,eeting}s,

                        Geert
Laura Abbott March 28, 2018, 5:27 p.m. | #4
On 03/28/2018 12:27 AM, Geert Uytterhoeven wrote:
> Hi Laura,
> 
> On Sat, Mar 10, 2018 at 1:10 AM, Laura Abbott <labbott@redhat.com> wrote:
>> The new challenge is to remove VLAs from the kernel
>> (see https://lkml.org/lkml/2018/3/7/621)
>>
>> This patch replaces a VLA with an appropriate call to kmalloc_array.
>>
>> Signed-off-by: Laura Abbott <labbott@redhat.com>
> 
> Thanks for your patch!
> 
>> --- a/drivers/gpio/gpio-xra1403.c
>> +++ b/drivers/gpio/gpio-xra1403.c
>> @@ -126,11 +126,16 @@ static void xra1403_dbg_show(struct seq_file *s, struct gpio_chip *chip)
>>   {
>>          int reg;
>>          struct xra1403 *xra = gpiochip_get_data(chip);
>> -       int value[xra1403_regmap_cfg.max_register];
> 
> Apparently xra1403_regmap_cfg.max_register is always 0x15?
> 
> What about adding
> 
>          #define XRA_LAST 15
> 
> at the top, and replacing both "XRA_IFR | 0x01" and
> xra1403_regmap_cfg.max_register by XRA_LAST instead?
> That would avoid doing yet another memory allocation over and over.
> 
> Gr{oetje,eeting}s,
> 
>                          Geert
> 

I'm okay with making the change but I think Linus already picked
up the patch into his gpio trees. Linus, do you want a patch on
top of your -devel branch or should I just send a new patch?

Thanks,
Laura
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Linus Walleij April 4, 2018, 12:53 p.m. | #5
On Wed, Mar 28, 2018 at 7:27 PM, Laura Abbott <labbott@redhat.com> wrote:
> On 03/28/2018 12:27 AM, Geert Uytterhoeven wrote:
>>
>> Hi Laura,
>>
>> On Sat, Mar 10, 2018 at 1:10 AM, Laura Abbott <labbott@redhat.com> wrote:
>>>
>>> The new challenge is to remove VLAs from the kernel
>>> (see https://lkml.org/lkml/2018/3/7/621)
>>>
>>> This patch replaces a VLA with an appropriate call to kmalloc_array.
>>>
>>> Signed-off-by: Laura Abbott <labbott@redhat.com>
>>
>>
>> Thanks for your patch!
>>
>>> --- a/drivers/gpio/gpio-xra1403.c
>>> +++ b/drivers/gpio/gpio-xra1403.c
>>> @@ -126,11 +126,16 @@ static void xra1403_dbg_show(struct seq_file *s,
>>> struct gpio_chip *chip)
>>>   {
>>>          int reg;
>>>          struct xra1403 *xra = gpiochip_get_data(chip);
>>> -       int value[xra1403_regmap_cfg.max_register];
>>
>>
>> Apparently xra1403_regmap_cfg.max_register is always 0x15?
>>
>> What about adding
>>
>>          #define XRA_LAST 15
>>
>> at the top, and replacing both "XRA_IFR | 0x01" and
>> xra1403_regmap_cfg.max_register by XRA_LAST instead?
>> That would avoid doing yet another memory allocation over and over.
>>
>> Gr{oetje,eeting}s,
>>
>>                          Geert
>>
>
> I'm okay with making the change but I think Linus already picked
> up the patch into his gpio trees. Linus, do you want a patch on
> top of your -devel branch or should I just send a new patch?

Yeah a patch on top is fine, I sent my pull request to Torvalds
today so we can take this as a fix for the -rc cycle simply.

Yours,
Linus Walleij
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Patch

diff --git a/drivers/gpio/gpio-xra1403.c b/drivers/gpio/gpio-xra1403.c
index 0230e4b7a2fb..8d4c8e99b251 100644
--- a/drivers/gpio/gpio-xra1403.c
+++ b/drivers/gpio/gpio-xra1403.c
@@ -126,11 +126,16 @@  static void xra1403_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 {
 	int reg;
 	struct xra1403 *xra = gpiochip_get_data(chip);
-	int value[xra1403_regmap_cfg.max_register];
+	int *value;
 	int i;
 	unsigned int gcr;
 	unsigned int gsr;
 
+	value = kmalloc_array(xra1403_regmap_cfg.max_register, sizeof(*value),
+				GFP_KERNEL);
+	if (!value)
+		return;
+
 	seq_puts(s, "xra reg:");
 	for (reg = 0; reg <= xra1403_regmap_cfg.max_register; reg++)
 		seq_printf(s, " %2.2x", reg);
@@ -154,6 +159,7 @@  static void xra1403_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 			   (gcr & BIT(i)) ? "in" : "out",
 			   (gsr & BIT(i)) ? "hi" : "lo");
 	}
+	kfree(value);
 }
 #else
 #define xra1403_dbg_show NULL