On Wed, Jul 24, 2019 at 10:11 AM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote: > > Describe what each input flag does and who uses it. > > Cc: Willem de Bruijn <willemb@xxxxxxxxxx> > Cc: Petar Penkov <ppenkov@xxxxxxxxxx> > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx> Acked-by: Song Liu <songliubraving@xxxxxx> > --- > Documentation/bpf/prog_flow_dissector.rst | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/Documentation/bpf/prog_flow_dissector.rst b/Documentation/bpf/prog_flow_dissector.rst > index ed343abe541e..0f3f380b2ce4 100644 > --- a/Documentation/bpf/prog_flow_dissector.rst > +++ b/Documentation/bpf/prog_flow_dissector.rst > @@ -26,6 +26,7 @@ and output arguments. > * ``nhoff`` - initial offset of the networking header > * ``thoff`` - initial offset of the transport header, initialized to nhoff > * ``n_proto`` - L3 protocol type, parsed out of L2 header > + * ``flags`` - optional flags > > Flow dissector BPF program should fill out the rest of the ``struct > bpf_flow_keys`` fields. Input arguments ``nhoff/thoff/n_proto`` should be > @@ -101,6 +102,23 @@ can be called for both cases and would have to be written carefully to > handle both cases. > > > +Flags > +===== > + > +``flow_keys->flags`` might contain optional input flags that work as follows: > + > +* ``FLOW_DISSECTOR_F_PARSE_1ST_FRAG`` - tells BPF flow dissector to continue > + parsing first fragment; the default expected behavior is that flow dissector > + returns as soon as it finds out that the packet is fragmented; > + used by ``eth_get_headlen`` to estimate length of all headers for GRO. > +* ``FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL`` - tells BPF flow dissector to stop > + parsing as soon as it reaches IPv6 flow label; used by ``___skb_get_hash`` > + and ``__skb_get_hash_symmetric`` to get flow hash. > +* ``FLOW_DISSECTOR_F_STOP_AT_ENCAP`` - tells BPF flow dissector to stop > + parsing as soon as it reaches encapsulated headers; used by routing > + infrastructure. > + > + > Reference Implementation > ======================== > > -- > 2.22.0.657.g960e92d24f-goog >
