Re: [PATCH] drm/exynos: gsc: allocate formats as a flexible array member

[Inki Dae]

Hi,

2026년 10월 5일 (월) 오전 9:11, Rosen Penev <rosenp@xxxxxxxxx>님이 작성:
>
> The formats array is allocated separately with devm_kcalloc() and only
> referenced through the gsc_context. Make it a flexible array member at
> the end of the context and allocate both in one go with struct_size().
>
> Annotate it with __counted_by(num_formats) so the array accesses can be
> bounds checked with FORTIFY_SOURCE and UBSAN_BOUNDS.
>
> Assisted-by: LLM

The allocation and lifetime changes look reasonable to me, but
Assisted-by: LLM causes checkpatch.pl to report a non-standard
signature and an unrecognized email address. Please describe the AI
assistance in the commit message prose instead.

Thanks,
Inki Dae

> Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_gsc.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gsc.c b/drivers/gpu/drm/exynos/exynos_drm_gsc.c
> index d9637ddfcfc4..f1807ef664e1 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gsc.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gsc.c
> @@ -99,7 +99,6 @@ struct gsc_context {
>         void            *dma_priv;
>         struct device   *dev;
>         struct exynos_drm_ipp_task      *task;
> -       struct exynos_drm_ipp_formats   *formats;
>         unsigned int                    num_formats;
>
>         void __iomem    *regs;
> @@ -110,6 +109,7 @@ struct gsc_context {
>         int     id;
>         int     irq;
>         bool    rotation;
> +       struct exynos_drm_ipp_formats   formats[] __counted_by(num_formats);
>  };
>
>  /**
> @@ -1222,21 +1222,19 @@ static int gsc_probe(struct platform_device *pdev)
>         struct gsc_context *ctx;
>         int num_formats, ret, i, j;
>
> -       ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> +       num_formats = ARRAY_SIZE(gsc_formats) + ARRAY_SIZE(gsc_tiled_formats);
> +       ctx = devm_kzalloc(dev, struct_size(ctx, formats, num_formats), GFP_KERNEL);
>         if (!ctx)
>                 return -ENOMEM;
>
> +       ctx->num_formats = num_formats;
> +       formats = ctx->formats;
> +
>         driver_data = device_get_match_data(dev);
>         ctx->dev = dev;
>         ctx->num_clocks = driver_data->num_clocks;
>         ctx->clk_names = driver_data->clk_names;
>
> -       /* construct formats/limits array */
> -       num_formats = ARRAY_SIZE(gsc_formats) + ARRAY_SIZE(gsc_tiled_formats);
> -       formats = devm_kcalloc(dev, num_formats, sizeof(*formats), GFP_KERNEL);
> -       if (!formats)
> -               return -ENOMEM;
> -
>         /* linear formats */
>         for (i = 0; i < ARRAY_SIZE(gsc_formats); i++) {
>                 formats[i].fourcc = gsc_formats[i];
> @@ -1256,9 +1254,6 @@ static int gsc_probe(struct platform_device *pdev)
>                 formats[j].num_limits = driver_data->num_limits;
>         }
>
> -       ctx->formats = formats;
> -       ctx->num_formats = num_formats;
> -
>         /* clock control */
>         for (i = 0; i < ctx->num_clocks; i++) {
>                 ctx->clocks[i] = devm_clk_get(dev, ctx->clk_names[i]);
> --
> 2.56.0
>
>