Re: [PATCH RFC] net/mlx4: Remove improper usage of dma_alloc_coherent().

[Ido Shamay]

On 4/13/2015 12:33 AM, Ido Shamay wrote:
> On 4/7/2015 10:43 PM, Ido Shamay wrote:
> > On 4/7/2015 2:00 AM, David Daney wrote:
> > > From: David Daney <david.daney@xxxxxxxxxx>
> > >
> > > The dma_alloc_coherent() function returns a virtual address which can
> > > be used for coherent access to the underlying memory.  On some
> > > architectures, like arm64, undefined behavior results if this memory is
> > > also accessed via virtual mappings that are not coherent. Because of
> > > their undefined nature, operations like virt_to_page() return garbage
> > > when passed virtual addresses obtained from dma_alloc_coherent().  Any
> > > subsequent mappings via vmap() of the garbage page values are unusable
> > > and result in bad things like bus errors (synchronous aborts in ARM64
> > > speak).
> > >
> > > The MLX4 driver contains code that does the equivalent of:
> > >
> > >    vmap(virt_to_page(dma_alloc_coherent))
> > >
> > > This results in an OOPs when the device is opened.
> > >
> > > To fix this...
> > >
> > > Always use result of dma_alloc_coherent() directly.
> Acked-by: Ido Shamay <idos@xxxxxxxxxxxx>
> Thanks David, this is good for us

Hi David,

Are you resending this patch or you want us to do that?

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