Re: [PATCH 2/2] arm64: bpf: add BPF XADD instruction

[Shi, Yang]

On 11/10/2015 4:08 PM, Eric Dumazet wrote:
> On Tue, 2015-11-10 at 14:41 -0800, Yang Shi wrote:
> > aarch64 doesn't have native support for XADD instruction, implement it by
> > the below instruction sequence:
> >
> > Load (dst + off) to a register
> > Add src to it
> > Store it back to (dst + off)
>
> Not really what is needed ?
>
> See this BPF_XADD as an atomic_add() equivalent.

I see. Thanks. The documentation doesn't say too much about "exclusive" 
add. If so it should need load-acquire/store-release.

I will rework it.

Yang

>

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