linux-kernel - Re: [PATCHv2 2/9] arch/arm/mm/dma-mapping.c: Convert to use vm_insert

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Message-ID: <CAFqt6zZCmUTf1Pj+i0eYeQJ1x8A5u+26cM0v00TRpiNYDHky8Q@mail.gmail.com>
Date:   Sun, 3 Feb 2019 17:46:02 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        robin.murphy@....com, iamjoonsoo.kim@....com, treding@...dia.com,
        Kees Cook <keescook@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     linux-kernel@...r.kernel.org, Linux-MM <linux-mm@...ck.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCHv2 2/9] arch/arm/mm/dma-mapping.c: Convert to use vm_insert_range

Hi Russell,

On Thu, Jan 31, 2019 at 8:34 AM Souptick Joarder <jrdr.linux@...il.com> wrote:
>
> Convert to use vm_insert_range() to map range of kernel
> memory to user vma.
>
> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>

Does it looks good ?

> ---
>  arch/arm/mm/dma-mapping.c | 22 ++++++----------------
>  1 file changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index f1e2922..915f701 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -1575,31 +1575,21 @@ static int __arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma
>                     void *cpu_addr, dma_addr_t dma_addr, size_t size,
>                     unsigned long attrs)
>  {
> -       unsigned long uaddr = vma->vm_start;
> -       unsigned long usize = vma->vm_end - vma->vm_start;
>         struct page **pages = __iommu_get_pages(cpu_addr, attrs);
>         unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
> -       unsigned long off = vma->vm_pgoff;
> +       int err;
>
>         if (!pages)
>                 return -ENXIO;
>
> -       if (off >= nr_pages || (usize >> PAGE_SHIFT) > nr_pages - off)
> +       if (vma->vm_pgoff >= nr_pages)
>                 return -ENXIO;
>
> -       pages += off;
> -
> -       do {
> -               int ret = vm_insert_page(vma, uaddr, *pages++);
> -               if (ret) {
> -                       pr_err("Remapping memory failed: %d\n", ret);
> -                       return ret;
> -               }
> -               uaddr += PAGE_SIZE;
> -               usize -= PAGE_SIZE;
> -       } while (usize > 0);
> +       err = vm_insert_range(vma, pages, nr_pages);
> +       if (err)
> +               pr_err("Remapping memory failed: %d\n", err);
>
> -       return 0;
> +       return err;
>  }
>  static int arm_iommu_mmap_attrs(struct device *dev,
>                 struct vm_area_struct *vma, void *cpu_addr,
> --
> 1.9.1
>