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From: Stanislav Fomichev <sdf@google.com>
To: netdev@vger.kernel.org, bpf@vger.kernel.org
Cc: davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net,
	Stanislav Fomichev <sdf@google.com>,
	Willem de Bruijn <willemb@google.com>,
	Song Liu <songliubraving@fb.com>,
	Petar Penkov <ppenkov@google.com>
Subject: [PATCH bpf-next v2 2/7] bpf/flow_dissector: document flags
Date: Thu, 25 Jul 2019 08:33:37 -0700	[thread overview]
Message-ID: <20190725153342.3571-3-sdf@google.com> (raw)
In-Reply-To: <20190725153342.3571-1-sdf@google.com>

Describe what each input flag does and who uses it.

Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Petar Penkov <ppenkov@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
 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.
+``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

  parent reply	other threads:[~2019-07-25 15:33 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-25 15:33 [PATCH bpf-next v2 0/7] bpf/flow_dissector: support input flags Stanislav Fomichev
2019-07-25 15:33 ` [PATCH bpf-next v2 1/7] bpf/flow_dissector: pass input flags to BPF flow dissector program Stanislav Fomichev
2019-07-25 19:58   ` Alexei Starovoitov
2019-07-25 20:03     ` Stanislav Fomichev
2019-07-25 15:33 ` Stanislav Fomichev [this message]
2019-07-25 15:33 ` [PATCH bpf-next v2 3/7] bpf/flow_dissector: support flags in BPF_PROG_TEST_RUN Stanislav Fomichev
2019-07-25 15:33 ` [PATCH bpf-next v2 4/7] tools/bpf: sync bpf_flow_keys flags Stanislav Fomichev
2019-07-25 15:33 ` [PATCH bpf-next v2 5/7] selftests/bpf: support FLOW_DISSECTOR_F_PARSE_1ST_FRAG Stanislav Fomichev
2019-07-25 17:15   ` Song Liu
2019-07-25 15:33 ` [PATCH bpf-next v2 6/7] bpf/flow_dissector: support ipv6 flow_label and FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL Stanislav Fomichev
2019-07-25 15:33 ` [PATCH bpf-next v2 7/7] selftests/bpf: support FLOW_DISSECTOR_F_STOP_AT_ENCAP Stanislav Fomichev
2019-07-25 17:05 ` [PATCH bpf-next v2 0/7] bpf/flow_dissector: support input flags Petar Penkov

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