[can-next 0/5] can: remove private skb headroom infrastructure

[Oliver Hartkopp <socketcan@hartkopp.net>]

CAN bus related skbuffs (ETH_P_CAN/ETH_P_CANFD/ETH_P_CANXL) simply contain
CAN frame structs for CAN CC/FD/XL of skb->len length at skb->data.
Those CAN skbs do not have network/mac/transport headers nor other such
references for encapsulated protocols like ethernet/IP protocols.

To store data for CAN specific use-cases all CAN bus related skbuffs are
created with a 16 byte private skb headroom (struct can_skb_priv).
Using the skb headroom and accessing skb->head for this private data
led to several problems in the past likely due to "The struct can_skb_priv
business is highly unconventional for the networking stack." [1]

This patch set aims to remove the unconventional skb headroom usage for
CAN bus related skbuffs. To store the data for CAN specific use-cases
unused space in CAN skbs is used, namely the inner protocol space for
ethernet/IP encapsulation.

[1] https://lore.kernel.org/linux-can/20260104074222.29e660ac@kernel.org/

Oliver Hartkopp (5):
  can: use skb hash instead of private variable in headroom
  can: move can_iif from private headroom to struct sk_buff
  can: move frame length from private headroom to struct sk_buff
  can: remove private skb headroom infrastructure
  can: gw: use new can_gw_hops variable instead of re-using csum_start

 drivers/net/can/dev/skb.c | 45 ++++++++++++++++-----------------------
 include/linux/can/core.h  |  1 +
 include/linux/can/skb.h   | 33 ----------------------------
 include/linux/skbuff.h    | 27 +++++++++++++++++------
 net/can/af_can.c          | 35 +++++++++++++++++++-----------
 net/can/bcm.c             | 13 ++++-------
 net/can/gw.c              | 25 ++++++----------------
 net/can/isotp.c           | 18 ++++++----------
 net/can/j1939/socket.c    |  7 ++----
 net/can/j1939/transport.c | 13 ++++-------
 net/can/raw.c             | 14 ++++++------
 11 files changed, 92 insertions(+), 139 deletions(-)

-- 
2.47.3