Re: [PATCH][next] drm/nouveau: fifo: Avoid -Wflex-array-member-not-at-end warning

[Gustavo A. R. Silva]

On 03/04/25 11:41, Gustavo A. R. Silva wrote:
> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
> getting ready to enable it, globally.
>
> Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of
> a flexible structure where the size of the flexible-array member
> is known at compile-time, and refactor the rest of the code,
> accordingly.
>
> So, with these changes, fix the following warning:
>
> drivers/gpu/drm/nouveau/nvif/fifo.c:29:42: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
>
> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/nouveau/nvif/fifo.c | 32 ++++++++++++-----------------
>   1 file changed, 13 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvif/fifo.c b/drivers/gpu/drm/nouveau/nvif/fifo.c
> index a463289962b2..f8772340fec4 100644
> --- a/drivers/gpu/drm/nouveau/nvif/fifo.c
> +++ b/drivers/gpu/drm/nouveau/nvif/fifo.c
> @@ -25,33 +25,28 @@ static int
>   nvif_fifo_runlists(struct nvif_device *device)
>   {
>   	struct nvif_object *object = &device->object;
> -	struct {
> -		struct nv_device_info_v1 m;
> -		struct {
> -			struct nv_device_info_v1_data runlists;
> -			struct nv_device_info_v1_data runlist[64];
> -		} v;
> -	} *a;
> +	DEFINE_RAW_FLEX(struct nv_device_info_v1, a, data, 65);
> +	struct nv_device_info_v1_data *runlists = &a->data[0];
> +	struct nv_device_info_v1_data *runlist = &a->data[1];
> +	const u8 rl_cnt = (__struct_size(a) - sizeof(*a)) / sizeof(*a->data) - 1;
>   	int ret, i;
>   
>   	if (device->runlist)
>   		return 0;
>   
> -	if (!(a = kmalloc(sizeof(*a), GFP_KERNEL)))

I'll send v2 preserving the above allocation (with some adjustments to
remove the flex-array-in-the-middle issue), as I just got this report
from the kernel test robot:

https://lore.kernel.org/lkml/202504041254.6e26LBdj-lkp@xxxxxxxxx/

Thanks
--
Gustavo