[PATCH v6 0/4] add feature arc in rte_graph

[Nitin Saxena <nsaxena@marvell.com>]

Feature arc represents an ordered list of features/protocols at a given
networking layer. It is a high level abstraction to connect various
rte_graph nodes, as feature nodes, and allow packets steering across
these nodes in a generic manner.

Features (or feature nodes) are nodes which handles partial or complete
handling of a protocol in fast path. Like ipv4-rewrite node, which adds
rewrite data to an outgoing IPv4 packet.

However in above example, outgoing interface(say "eth0") may have
outbound IPsec policy enabled, hence packets must be steered from
ipv4-rewrite node to ipsec-outbound-policy node for outbound IPsec
policy lookup. On the other hand, packets routed to another interface
(eth1) will not be sent to ipsec-outbound-policy node as IPsec feature
is disabled on eth1. Feature-arc allows rte_graph applications to manage
such constraints easily

Feature arc abstraction allows rte_graph based application to

1. Seamlessly steer packets across feature nodes based on whether
feature is enabled or disabled on an interface. Features enabled on one
interface may not be enabled on another interface with in a same feature
arc.

2. Allow enabling/disabling of features on an interface at runtime,
so that if a feature is disabled, packets associated with that interface
won't be steered to corresponding feature node.

3. Provides mechanism to hook custom/user-defined nodes to a feature
node and allow packet steering from feature node to custom node without
changing former's fast path function

4. Allow expressing features in a particular sequential order so that
packets are steered in an ordered way across nodes in fast path. For
eg: if IPsec and IPv4 features are enabled on an ingress interface,
packets must be sent to IPsec inbound policy node first and then to ipv4
lookup node.

This patch series adds feature arc library in rte_graph and also adds
"ipv4-output" feature arc handling in "ipv4-rewrite" node.

Changes in v6:
- Rebased to latest main for DPDK-25.03
- Added constructor based feature arc/feature registration
- Changed design to handle fast path synchronization via RCU mechanism
  when any feature is enabled or disabled
- Added feature arc specific mbuf dynamic field to carry feature data
  across nodes
- Added feature arc example in app/graph
- Programming guide and functional test cases in future versions

Nitin Saxena (4):
  graph: add API to override node process function
  graph: add feature arc abstraction
  ip4: add ip4 output feature arc
  app/graph: add custom feature nodes for ip4 output arc

 app/graph/commands.list                  |    6 +
 app/graph/feature.c                      |  141 ++
 app/graph/feature.h                      |   13 +
 app/graph/graph.c                        |    4 +
 app/graph/ip4_output_hook.c              |  169 ++
 app/graph/main.c                         |   15 +-
 app/graph/meson.build                    |    2 +
 app/graph/module_api.h                   |    2 +
 doc/api/doxy-api-index.md                |    2 +
 doc/guides/rel_notes/release_25_03.rst   |   10 +
 lib/graph/graph_feature_arc.c            | 1780 ++++++++++++++++++++++
 lib/graph/graph_private.h                |   15 +
 lib/graph/meson.build                    |    4 +-
 lib/graph/node.c                         |   23 +
 lib/graph/rte_graph_feature_arc.h        |  552 +++++++
 lib/graph/rte_graph_feature_arc_worker.h |  608 ++++++++
 lib/graph/version.map                    |   20 +
 lib/node/ethdev_ctrl.c                   |    8 +
 lib/node/interface_tx_feature.c          |  133 ++
 lib/node/interface_tx_feature_priv.h     |   33 +
 lib/node/ip4_rewrite.c                   |  298 +++-
 lib/node/meson.build                     |    1 +
 lib/node/node_private.h                  |    1 +
 lib/node/rte_node_ip4_api.h              |    4 +
 24 files changed, 3838 insertions(+), 6 deletions(-)
 create mode 100644 app/graph/feature.c
 create mode 100644 app/graph/feature.h
 create mode 100644 app/graph/ip4_output_hook.c
 create mode 100644 lib/graph/graph_feature_arc.c
 create mode 100644 lib/graph/rte_graph_feature_arc.h
 create mode 100644 lib/graph/rte_graph_feature_arc_worker.h
 create mode 100644 lib/node/interface_tx_feature.c
 create mode 100644 lib/node/interface_tx_feature_priv.h

-- 
2.43.0