[PATCH] amba: tegra-ahb: Replace zero-length array with flexible-array member

[PATCH] amba: tegra-ahb: Replace zero-length array with flexible-array member

[Gustavo A. R. Silva]

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertenly introduced[3] to the codebase from now on.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/amba/tegra-ahb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/amba/tegra-ahb.c b/drivers/amba/tegra-ahb.c
index b0b688c481e8..e9e5c7bb580c 100644
--- a/drivers/amba/tegra-ahb.c
+++ b/drivers/amba/tegra-ahb.c
@@ -129,7 +129,7 @@ static const u32 tegra_ahb_gizmo[] = {
 struct tegra_ahb {
 	void __iomem	*regs;
 	struct device	*dev;
-	u32		ctx[0];
+	u32		ctx[];
 };
 
 static inline u32 gizmo_readl(struct tegra_ahb *ahb, u32 offset)
-- 
2.25.0

Re: [PATCH] amba: tegra-ahb: Replace zero-length array with flexible-array member

[Gustavo A. R. Silva]

Hi all,

Friendly ping: Who can take this?

Thanks
--
Gustavo

On 2/11/20 15:02, Gustavo A. R. Silva wrote:
> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
> 
> struct foo {
>         int stuff;
>         struct boo array[];
> };
> 
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertenly introduced[3] to the codebase from now on.
> 
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo-L1vi/lXTdts+Va1GwOuvDg@public.gmane.org>
> ---
>  drivers/amba/tegra-ahb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/amba/tegra-ahb.c b/drivers/amba/tegra-ahb.c
> index b0b688c481e8..e9e5c7bb580c 100644
> --- a/drivers/amba/tegra-ahb.c
> +++ b/drivers/amba/tegra-ahb.c
> @@ -129,7 +129,7 @@ static const u32 tegra_ahb_gizmo[] = {
>  struct tegra_ahb {
>  	void __iomem	*regs;
>  	struct device	*dev;
> -	u32		ctx[0];
> +	u32		ctx[];
>  };
>  
>  static inline u32 gizmo_readl(struct tegra_ahb *ahb, u32 offset)
> 

Re: [PATCH] amba: tegra-ahb: Replace zero-length array with flexible-array member

[Gustavo A. R. Silva]

Hi all,

Friendly ping (second time): Who can take this?

Thanks
--
Gustavo

On 2/27/20 1:33 PM, Gustavo A. R. Silva wrote:
> Hi all,
> 
> Friendly ping: Who can take this?
> 
> Thanks
> --
> Gustavo
> 
> On 2/11/20 15:02, Gustavo A. R. Silva wrote:
>> The current codebase makes use of the zero-length array language
>> extension to the C90 standard, but the preferred mechanism to declare
>> variable-length types such as these ones is a flexible array member[1][2],
>> introduced in C99:
>>
>> struct foo {
>>         int stuff;
>>         struct boo array[];
>> };
>>
>> By making use of the mechanism above, we will get a compiler warning
>> in case the flexible array does not occur last in the structure, which
>> will help us prevent some kind of undefined behavior bugs from being
>> inadvertenly introduced[3] to the codebase from now on.
>>
>> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
>> [2] https://github.com/KSPP/linux/issues/21
>> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>> ---
>>  drivers/amba/tegra-ahb.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/amba/tegra-ahb.c b/drivers/amba/tegra-ahb.c
>> index b0b688c481e8..e9e5c7bb580c 100644
>> --- a/drivers/amba/tegra-ahb.c
>> +++ b/drivers/amba/tegra-ahb.c
>> @@ -129,7 +129,7 @@ static const u32 tegra_ahb_gizmo[] = {
>>  struct tegra_ahb {
>>  	void __iomem	*regs;
>>  	struct device	*dev;
>> -	u32		ctx[0];
>> +	u32		ctx[];
>>  };
>>  
>>  static inline u32 gizmo_readl(struct tegra_ahb *ahb, u32 offset)
>>