Re: [PATCH bpf v4 2/2] bpf, sockmap: sk_prot needs inuse_idx set for proc stats

On Mon, Jul 12, 2021 at 12:56 PM John Fastabend
[off-list ref] wrote:

Proc socket stats use sk_prot->inuse_idx value to record inuse sock stats.
We currently do not set this correctly from sockmap side. The result is
reading sock stats '/proc/net/sockstat' gives incorrect values. The
socket counter is incremented correctly, but because we don't set the
counter correctly when we replace sk_prot we may omit the decrement.

To get the correct inuse_idx value move the core_initcall that initializes
the tcp/udp proto handlers to late_initcall. This way it is initialized
after TCP/UDP has the chance to assign the inuse_idx value from the
register protocol handler.

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>

For IPv6, I think the module is always loaded before we can
trigger tcp_bpf_check_v6_needs_rebuild(). So,

Reviewed-by: Cong Wang <redacted>

Thanks.