Re: [PATCH bpf-next 2/2] libbpf, xsk: add libbpf_smp_store_release libbpf_smp_load_acquire

On 2021-03-01 17:10, Toke Høiland-Jørgensen wrote:

Björn Töpel [off-list ref] writes:

quoted

From: Björn Töpel <redacted>

Now that the AF_XDP rings have load-acquire/store-release semantics,
move libbpf to that as well.

The library-internal libbpf_smp_{load_acquire,store_release} are only
valid for 32-bit words on ARM64.

Also, remove the barriers that are no longer in use.

So what happens if an updated libbpf is paired with an older kernel (or
vice versa)?

"This is fine." ;-) This was briefly discussed in [1], outlined by the
previous commit!

...even on POWER.


Björn

[1] https://lore.kernel.org/bpf/20200316184423.GA14143@willie-the-truck/ (local)

-Toke