Re: [PATCH v3 0/5] add feature arc in rte_graph

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 9 Oct 2024 18:59:57 +0530
Nitin Saxena <nsaxena@marvell.com> wrote:

> 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 v3:
> - rte_graph_feature_arc_t typedef from uint64_t to uintptr_t to fix
>   compilation on 32-bit machine
> - Updated images in .png format
> - Added ABI change section in release notes
> - Fixed DPDK CI failures
> 
> Changes in v2:
> - Added unit tests for feature arc
> - Fixed issues found in testing
> - Added new public APIs rte_graph_feature_arc_feature_to_node(),
>   rte_graph_feature_arc_feature_to_name(),
>   rte_graph_feature_arc_num_features()
> - Added programming guide for feature arc
> - Added release notes for feature arc
> 
> Nitin Saxena (5):
>   graph: add feature arc support
>   graph: add feature arc option in graph create
>   graph: add IPv4 output feature arc
>   test/graph_feature_arc: add functional tests
>   docs: add programming guide for feature arc
> 
>  app/test/meson.build                        |    1 +
>  app/test/test_graph_feature_arc.c           | 1410 +++++++++++++++++++
>  doc/guides/prog_guide/graph_lib.rst         |  288 ++++
>  doc/guides/prog_guide/img/feature_arc-1.png |  Bin 0 -> 61532 bytes
>  doc/guides/prog_guide/img/feature_arc-2.png |  Bin 0 -> 155806 bytes
>  doc/guides/prog_guide/img/feature_arc-3.png |  Bin 0 -> 143697 bytes
>  doc/guides/rel_notes/release_24_11.rst      |   13 +
>  lib/graph/graph.c                           |    1 +
>  lib/graph/graph_feature_arc.c               | 1223 ++++++++++++++++
>  lib/graph/graph_populate.c                  |    7 +-
>  lib/graph/graph_private.h                   |    3 +
>  lib/graph/meson.build                       |    2 +
>  lib/graph/node.c                            |    2 +
>  lib/graph/rte_graph.h                       |    3 +
>  lib/graph/rte_graph_feature_arc.h           |  431 ++++++
>  lib/graph/rte_graph_feature_arc_worker.h    |  674 +++++++++
>  lib/graph/version.map                       |   20 +
>  lib/node/ip4_rewrite.c                      |  476 +++++--
>  lib/node/ip4_rewrite_priv.h                 |   15 +-
>  lib/node/node_private.h                     |   20 +-
>  lib/node/rte_node_ip4_api.h                 |    3 +
>  21 files changed, 4494 insertions(+), 98 deletions(-)
>  create mode 100644 app/test/test_graph_feature_arc.c
>  create mode 100644 doc/guides/prog_guide/img/feature_arc-1.png
>  create mode 100644 doc/guides/prog_guide/img/feature_arc-2.png
>  create mode 100644 doc/guides/prog_guide/img/feature_arc-3.png
>  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
> 

Looks good, but likely missing an RTE_ATOMIC() around the feature enable bitmask.
Build fails:

####################################################################################
#### [Begin job log] "ubuntu-22.04-clang-stdatomic" at step Build and test
####################################################################################
        rte_atomic_store_explicit(&arc->feature_enable_bitmask[passive_list], bitmask,
        ^                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../lib/eal/include/rte_stdatomic.h:76:2: note: expanded from macro 'rte_atomic_store_explicit'
        atomic_store_explicit(ptr, val, memorder)
        ^                     ~~~
/usr/lib/llvm-14/lib/clang/14.0.0/include/stdatomic.h:127:31: note: expanded from macro 'atomic_store_explicit'
#define atomic_store_explicit __c11_atomic_store
                              ^
../lib/graph/graph_feature_arc.c:1084:2: error: address argument to atomic operation must be a pointer to _Atomic type ('rte_graph_feature_rt_list_t *' (aka 'unsigned short *') invalid)
        rte_atomic_store_explicit(&arc->active_feature_list, passive_list,
        ^                         ~~~~~~~~~~~~~~~~~~~~~~~~~
../lib/eal/include/rte_stdatomic.h:76:2: note: expanded from macro 'rte_atomic_store_explicit'
        atomic_store_explicit(ptr, val, memorder)
        ^                     ~~~
/usr/lib/llvm-14/lib/clang/14.0.0/include/stdatomic.h:127:31: note: expanded from macro 'atomic_store_explicit'
#define atomic_store_explicit __c11_atomic_store
                              ^
10 errors generated.