[PATCH] net/macmace: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

[PATCH] net/macmace: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

[Atul Raut]

Since zero-length arrays are deprecated, we are replacing
them with C99 flexible-array members. As a result, instead
of declaring a zero-length array, use the new
DECLARE_FLEX_ARRAY() helper macro.

This fixes warnings such as:
./drivers/net/ethernet/apple/macmace.c:80:4-8: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)

Signed-off-by: Atul Raut <rauji.raut@gmail.com>
---
 drivers/net/ethernet/apple/macmace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/apple/macmace.c b/drivers/net/ethernet/apple/macmace.c
index 8fcaf1639920..8775c3234e91 100644
--- a/drivers/net/ethernet/apple/macmace.c
+++ b/drivers/net/ethernet/apple/macmace.c
@@ -77,7 +77,7 @@ struct mace_frame {
 	u8	pad4;
 	u32	pad5;
 	u32	pad6;
-	u8	data[1];
+	DECLARE_FLEX_ARRAY(u8, data);
 	/* And frame continues.. */
 };
 
-- 
2.34.1

Re: [PATCH] net/macmace: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

[Leon Romanovsky]

On Sun, Jul 30, 2023 at 04:14:42PM -0700, Atul Raut wrote:
> Since zero-length arrays are deprecated, we are replacing
> them with C99 flexible-array members. As a result, instead
> of declaring a zero-length array, use the new
> DECLARE_FLEX_ARRAY() helper macro.
> 
> This fixes warnings such as:
> ./drivers/net/ethernet/apple/macmace.c:80:4-8: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
> 
> Signed-off-by: Atul Raut <rauji.raut@gmail.com>
> ---
>  drivers/net/ethernet/apple/macmace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/apple/macmace.c b/drivers/net/ethernet/apple/macmace.c
> index 8fcaf1639920..8775c3234e91 100644
> --- a/drivers/net/ethernet/apple/macmace.c
> +++ b/drivers/net/ethernet/apple/macmace.c
> @@ -77,7 +77,7 @@ struct mace_frame {
>  	u8	pad4;
>  	u32	pad5;
>  	u32	pad6;
> -	u8	data[1];
> +	DECLARE_FLEX_ARRAY(u8, data);

But data[1] is not zero-length array.

>  	/* And frame continues.. */
>  };
>  
> -- 
> 2.34.1
> 
> 

Re: [PATCH] net/macmace: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

[Larysa Zaremba]

On Mon, Jul 31, 2023 at 10:38:01AM +0300, Leon Romanovsky wrote:
> On Sun, Jul 30, 2023 at 04:14:42PM -0700, Atul Raut wrote:
> > Since zero-length arrays are deprecated, we are replacing
> > them with C99 flexible-array members. As a result, instead
> > of declaring a zero-length array, use the new
> > DECLARE_FLEX_ARRAY() helper macro.
> > 
> > This fixes warnings such as:
> > ./drivers/net/ethernet/apple/macmace.c:80:4-8: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
> > 
> > Signed-off-by: Atul Raut <rauji.raut@gmail.com>
> > ---
> >  drivers/net/ethernet/apple/macmace.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/apple/macmace.c b/drivers/net/ethernet/apple/macmace.c
> > index 8fcaf1639920..8775c3234e91 100644
> > --- a/drivers/net/ethernet/apple/macmace.c
> > +++ b/drivers/net/ethernet/apple/macmace.c
> > @@ -77,7 +77,7 @@ struct mace_frame {
> >  	u8	pad4;
> >  	u32	pad5;
> >  	u32	pad6;
> > -	u8	data[1];
> > +	DECLARE_FLEX_ARRAY(u8, data);
> 
> But data[1] is not zero-length array.
> 

So, please, if you are certain that data should be a flexible array,
send v2 without calling data a zero-length array. Also, with such change, I 
think driver code could be improved in many places in the same patchset.

> >  	/* And frame continues.. */
> >  };
> >  
> > -- 
> > 2.34.1
> > 
> > 
> 

Re: [PATCH] net/macmace: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

[Jakub Kicinski]

On Tue, 1 Aug 2023 16:09:37 +0200 Larysa Zaremba wrote:
> > > -	u8	data[1];
> > > +	DECLARE_FLEX_ARRAY(u8, data);  
> > 
> > But data[1] is not zero-length array.
> 
> So, please, if you are certain that data should be a flexible array,
> send v2 without calling data a zero-length array. Also, with such change, I 
> think driver code could be improved in many places in the same patchset.

Atul, you should respond to reviewers promptly. These are legit
questions.
On closer inspection the patch looks fine so to avoid clogging up 
the review queue and wasting more time on it I'm just going to apply it.

Re: [PATCH] net/macmace: Replace zero-length array with DECLARE_FLEX_ARRAY() helper

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Sun, 30 Jul 2023 16:14:42 -0700 you wrote:
> Since zero-length arrays are deprecated, we are replacing
> them with C99 flexible-array members. As a result, instead
> of declaring a zero-length array, use the new
> DECLARE_FLEX_ARRAY() helper macro.
> 
> This fixes warnings such as:
> ./drivers/net/ethernet/apple/macmace.c:80:4-8: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
> 
> [...]

Here is the summary with links:
  - net/macmace: Replace zero-length array with DECLARE_FLEX_ARRAY() helper
    https://git.kernel.org/netdev/net-next/c/005c9600003e

You are awesome, thank you!
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