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SubjectRe: [PATCH] staging: greybus: Replace zero-length array with flexible-array member
On Tue, Feb 11, 2020 at 03:12:19PM -0600, 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.
>
> This issue was found with the help of Coccinelle.

Looks like the scripts may need to be updated. You missed at least a
couple of instances:

$ git grep '\[0\];' drivers/staging/greybus/
drivers/staging/greybus/audio_apbridgea.h: __u8 data[0];
...
drivers/staging/greybus/usb.c: u8 buf[0];

Would you mind replacing these as well so that we really do this in one
patch per subsystem?

> [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/staging/greybus/raw.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/greybus/raw.c b/drivers/staging/greybus/raw.c
> index 838acbe84ca0..2b301b2aa107 100644
> --- a/drivers/staging/greybus/raw.c
> +++ b/drivers/staging/greybus/raw.c
> @@ -30,7 +30,7 @@ struct gb_raw {
> struct raw_data {
> struct list_head entry;
> u32 len;
> - u8 data[0];
> + u8 data[];
> };
>
> static struct class *raw_class;

Thanks,
Johan

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