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

[David Miller]

From: Alexei Starovoitov <alexei.starovoitov at gmail.com>
Date: Wed, 11 Nov 2015 09:27:00 -0800

> BPF_XADD == atomic_add() in kernel. period.
> we are not going to deprecate it or introduce something else.

Agreed, it makes no sense to try and tie C99 or whatever atomic
semantics to something that is already clearly defined to have
exactly kernel atomic_add() semantics.