[RFC net-next 0/2] DSA slave with customise netdev features

[DENG Qingfang <dqfext@gmail.com>]

Some taggers, such as tag_dsa.c, combine VLAN tags with DSA tags, which
currently has a few problems:

1. Unnecessary reallocation on TX:

A central TX reallocation has been used since commit a3b0b6479700
("net: dsa: implement a central TX reallocation procedure"), but for
VLAN-tagged frames, the actual headroom required for DSA taggers which
combine with VLAN tags is smaller.

2. Repeated memmoves:

If a both Marvell EDSA and VLAN tagged frame is received, the current
code will move the (DA,SA) twice: the first in dsa_rcv_ll to convert the
frame to a normal 802.1Q frame, and the second to strip off the 802.1Q
tag. The similar thing happens on TX.

For these tags, it is better to handle DSA and VLAN tags at the same time
in DSA taggers.

This patch set allows taggers to add custom netdev features to DSA
slaves so they can advertise VLAN offload, and converts tag_mtk to use
the TX VLAN offload.

DENG Qingfang (2):
  net: dsa: allow taggers to customise netdev features
  net: dsa: tag_mtk: handle VLAN tag insertion on TX

 include/net/dsa.h |  2 ++
 net/dsa/slave.c   |  3 ++-
 net/dsa/tag_mtk.c | 46 ++++++++++++++++++++++------------------------
 3 files changed, 26 insertions(+), 25 deletions(-)

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2.25.1