Re: [RFC v4] Add TCP encap_rcv hook (repost)

This hook is based on a hook of the same name provided by UDP.  It
provides
a way for to receive packets that have a TCP header and treat them in
some
alternate way.

It is intended to be used by an implementation of the STT tunneling
protocol within Open vSwtich's datapath. A prototype of such an
implementation has been made.

The STT draft is available at
http://tools.ietf.org/html/draft-davie-stt-01

My prototype STT implementation has been posted to the
dev-UOEtcQmXneFl884UGnbwIQ@public.gmane.org
The second version can be found at:
http://www.mail-archive.com/dev-yBygre7rU0TnMu66kgdUjQ@public.gmane.org/msg09001.html
It needs to be updated to call tcp_encap_enable()

Cc: Eric Dumazet <redacted>
Signed-off-by: Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>


+static struct static_key tcp_encap_needed __read_mostly;
+void tcp_encap_enable(void)
+{
+	if (!static_key_enabled(&tcp_encap_needed))
+		static_key_slow_inc(&tcp_encap_needed);
+}
+EXPORT_SYMBOL(tcp_encap_enable);

I have reservations about adding such a hook. but if we
must, then the hook must be GPL only.