[PATCH RFC net-next 00/20] net: dsa: add GRO support

[Alexander Lobakin]

As of now, napi_gro_receive() in cases where the corresponding
device is installed as CPU port of DSA-driven switch is in fact
an overheaded version of netif_receive_skb{,_list}() with no
advantages over:

- dev_gro_receive() can't find packet_offload for ETH_P_XDSA type;
- so it immediately returns GRO_NORMAL;
- napi_skb_finish() passes skb to gro_normal_one() -> netstack.

This series adds a basic infrastructure to allow DSA taggers to
implement GRO callbacks and adds GRO support for 5 tagger drivers:
* tag_ar9331
* tag_gswip
* tag_lan9303
* tag_mtk
* tag_qca

I didn't make it for the rest because they are in fact way more
complicated (e.g. combined DSA + 802.1q tag etc.) and require
more familiarity with them and tests on the real hardware, which
is inaccesible for me at the moment.

This series also includes a bunch of random fixes in several tagger
drivers and some cleanup. I left them all in one place as they depend
on each other, but there's no problem for me to split this into
different series.

I mark this as RFC, and there are the key questions for maintainers,
developers, users etc.:
- Do we need GRO support for DSA at all?
- Which tagger protocols really need it and which don't?
- Are the actual changes correct in every single tagger code?
- Does this series bring any performance improvements on the
  affected systems?
- Would anybody mind if we'd add DSA support to napi_gro_frags()?
- Any code/other comments/notes.

I also would like to see more taggers with GRO callbacks, such as
DSA and EDSA, and the results of their addition.

Alexander Lobakin (20):
  net: dsa: make .flow_dissect() callback returning void
  net: dsa: add GRO support infrastructure
  net: dsa: tag_ar9331: add .flow_dissect() callback
  net: dsa: tag_ar9331: split out common tag accessors
  net: dsa: tag_ar9331: add GRO callbacks
  net: dsa: tag_gswip: fix typo in tag name
  net: dsa: tag_gswip: switch to bitfield helpers
  net: dsa: tag_gswip: add .flow_dissect() callback
  net: dsa: tag_gswip: split out common tag accessors
  net: dsa: tag_gswip: add GRO callbacks
  net: dsa: tag_lan9303: add .flow_dissect() callback
  net: dsa: tag_lan9303: split out common tag accessors
  net: dsa: tag_lan9303: add GRO callbacks
  net: dsa: tag_mtk: split out common tag accessors
  net: dsa: tag_mtk: add GRO callbacks
  net: dsa: tag_qca: fix doubled Tx statistics
  net: dsa: tag_qca: switch to bitfield helpers
  net: dsa: tag_qca: split out common tag accessors
  net: dsa: tag_qca: add GRO callbacks
  net: core: add (unlikely) DSA support in napi_gro_frags()

 include/net/dsa.h         |  10 ++-
 net/core/dev.c            |  11 ++-
 net/core/flow_dissector.c |   8 +-
 net/dsa/dsa.c             |  43 +++++++++-
 net/dsa/dsa2.c            |   1 +
 net/dsa/tag_ar9331.c      | 139 ++++++++++++++++++++++++++-----
 net/dsa/tag_dsa.c         |   5 +-
 net/dsa/tag_edsa.c        |   5 +-
 net/dsa/tag_gswip.c       | 126 +++++++++++++++++++++++-----
 net/dsa/tag_lan9303.c     | 139 ++++++++++++++++++++++++++-----
 net/dsa/tag_mtk.c         | 115 +++++++++++++++++++++-----
 net/dsa/tag_qca.c         | 167 ++++++++++++++++++++++++++++----------
 12 files changed, 629 insertions(+), 140 deletions(-)

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2.24.1