netdev - [net-next 0/6] move CAN skb headroom content to skb extensions

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Message-ID: <20260125201601.5018-1-socketcan@hartkopp.net>
Date: Sun, 25 Jan 2026 21:15:55 +0100
From: Oliver Hartkopp <socketcan@...tkopp.net>
To: netdev@...r.kernel.org,
	linux-can@...r.kernel.org
Cc: Oliver Hartkopp <socketcan@...tkopp.net>
Subject: [net-next 0/6] move CAN skb headroom content to skb extensions

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 and use the common skb extensions instead.

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

Oliver Hartkopp (6):
  can: use skb hash instead of private variable in headroom
  can: add CAN skb extension infrastructure
  can: move ifindex to CAN skb extensions
  can: move frame_len to CAN skb extensions
  can: remove private CAN skb headroom infrastructure
  can: gw: use can_gw_hops instead of sk_buff::csum_start

 MAINTAINERS               |   1 +
 drivers/net/can/dev/skb.c | 123 ++++++++++++++++++++++++--------------
 include/linux/can/core.h  |   1 +
 include/linux/can/skb.h   |  32 ++--------
 include/linux/skbuff.h    |   3 +
 include/net/can.h         |  28 +++++++++
 net/can/Kconfig           |   1 +
 net/can/af_can.c          |  23 +++++--
 net/can/bcm.c             |  26 +++++---
 net/can/gw.c              |  38 ++++++------
 net/can/isotp.c           |  45 +++++++++-----
 net/can/j1939/socket.c    |  15 +++--
 net/can/j1939/transport.c |  28 ++++++---
 net/can/raw.c             |  21 ++++---
 net/core/skbuff.c         |   4 ++
 15 files changed, 248 insertions(+), 141 deletions(-)
 create mode 100644 include/net/can.h

-- 
2.47.3