linux-kernel - Re: [PATCH 27/67] dma-direct: add dma address sanity checks

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Date:   Fri, 29 Dec 2017 15:12:25 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Christoph Hellwig <hch@....de>
Cc:     iommu@...ts.linux-foundation.org,
        Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
        linux-ia64@...r.kernel.org,
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Subject: Re: [PATCH 27/67] dma-direct: add dma address sanity checks

Hi Christoph,

On Fri, Dec 29, 2017 at 9:18 AM, Christoph Hellwig <hch@....de> wrote:
> Roughly based on the x86 pci-nommu implementation.
>
> Signed-off-by: Christoph Hellwig <hch@....de>

Thanks for your patch!

> --- a/lib/dma-direct.c
> +++ b/lib/dma-direct.c
> @@ -9,6 +9,24 @@
>  #include <linux/scatterlist.h>
>  #include <linux/pfn.h>
>
> +#define DIRECT_MAPPING_ERROR           0
> +
> +static bool
> +check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
> +               const char *caller)
> +{
> +       if (unlikely(dev && !dma_capable(dev, dma_addr, size))) {
> +               if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
> +                       dev_err(dev,
> +                               "%s: overflow %llx+%zu of device mask %llx\n",

Please use "%pad" to format dma_addr_t ...

> +                               caller, (long long)dma_addr, size,

... and use &dma_addr.

> +                               (long long)*dev->dma_mask);

This cast is not needed, as u64 is unsigned long long in kernelspace on
all architectures.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

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