Re: [PATCH] spi: Fix invalid sgs value

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Biju,

On Mon, Mar 7, 2022 at 7:01 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> max_seg_size is unsigned int and it can have a value up to 2^32
> (for eg:-RZ_DMAC driver sets dma_set_max_seg_size as U32_MAX)
> When this value is used in min_t() as an integer type, it becomes
> -1 and the value of sgs becomes 0.
>
> Fix this issue by replacing the 'int' data type with 'unsigned int'
> in min_t().
>
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Thanks for your patch!

> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -1019,10 +1019,10 @@ int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
>         int i, ret;
>
>         if (vmalloced_buf || kmap_buf) {
> -               desc_len = min_t(int, max_seg_size, PAGE_SIZE);
> +               desc_len = min_t(unsigned int, max_seg_size, PAGE_SIZE);
>                 sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
>         } else if (virt_addr_valid(buf)) {
> -               desc_len = min_t(int, max_seg_size, ctlr->max_dma_len);
> +               desc_len = min_t(unsigned int, max_seg_size, (unsigned int)ctlr->max_dma_len);

The cast of the last parameter is not needed.

>                 sgs = DIV_ROUND_UP(len, desc_len);
>         } else {
>                 return -EINVAL;

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds