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

[David Miller]

From: Alexei Starovoitov <alexei.starovoitov at gmail.com>
Date: Wed, 11 Nov 2015 10:11:33 -0800

> bpf_xadd was never meant to be __sync_fetch_and_add equivalent.
> From the day one it meant to be atomic_add() as kernel does it.

+1

> I did piggy back on __sync in the llvm backend because it was the quick
> and dirty way to move forward.
> In retrospect I should have introduced a clean intrinstic for that instead,
> but it's not too late to do it now. user space we can change at any time
> unlike kernel.

+1