[PATCH 0/4] can: automate IFF_ECHO flag for generic echo skbs

[Vincent Mailhol <mailhol@kernel.org>]

Most CAN drivers allocate echo skb slots through alloc_candev() or
alloc_candev_mqs(), but still have to manually set IFF_ECHO to tell
PF_CAN that the driver handles local echo itself. This creates
boilerplate and makes it easy for drivers to forget one half of the
setup.

A recent example is commit c77bfbdd6aac ("can: dummy_can:
dummy_can_init(): fix packet statistics"), where dummy_can was already
using the generic echo skb helpers but needed an explicit IFF_ECHO
assignment to make tx_bytes accounting work.

Patch #1 cleans up slcan, which does not use the generic echo skb
helpers and therefore should not allocate echo slots. Patch #2 fixes a
small inaccuracy in the can.rst documentation in regard to the IFF_ECHO
flag. Patch #3 sets IFF_ECHO automatically when echo skb slots are
requested. And Patch #4, the final one, removes the now redundant
IFF_ECHO assignments from drivers which are covered by alloc_candev()
with a non-zero echo_skb_max.

The remaining explicit IFF_ECHO assignments are special cases with
custom or virtual echo handling.

Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
---
Vincent Mailhol (4):
      can: slcan: do not allocate unused echo skb
      can: fix IFF_ECHO example in documentation
      can: dev: set IFF_ECHO when allocating echo skbs
      can: treewide: remove redundant IFF_ECHO assignments

 Documentation/networking/can.rst                   | 7 +++++--
 drivers/net/can/at91_can.c                         | 1 -
 drivers/net/can/bxcan.c                            | 1 -
 drivers/net/can/c_can/c_can_main.c                 | 1 -
 drivers/net/can/cc770/cc770.c                      | 2 --
 drivers/net/can/ctucanfd/ctucanfd_base.c           | 1 -
 drivers/net/can/dev/dev.c                          | 1 +
 drivers/net/can/dummy_can.c                        | 1 -
 drivers/net/can/esd/esd_402_pci-core.c             | 1 -
 drivers/net/can/flexcan/flexcan-core.c             | 1 -
 drivers/net/can/ifi_canfd/ifi_canfd.c              | 1 -
 drivers/net/can/kvaser_pciefd/kvaser_pciefd_core.c | 1 -
 drivers/net/can/m_can/m_can.c                      | 1 -
 drivers/net/can/mscan/mscan.c                      | 2 --
 drivers/net/can/peak_canfd/peak_canfd.c            | 1 -
 drivers/net/can/rcar/rcar_can.c                    | 1 -
 drivers/net/can/rcar/rcar_canfd.c                  | 1 -
 drivers/net/can/rockchip/rockchip_canfd-core.c     | 1 -
 drivers/net/can/sja1000/sja1000.c                  | 1 -
 drivers/net/can/slcan/slcan-core.c                 | 2 +-
 drivers/net/can/softing/softing_main.c             | 1 -
 drivers/net/can/spi/hi311x.c                       | 1 -
 drivers/net/can/spi/mcp251x.c                      | 1 -
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c     | 1 -
 drivers/net/can/sun4i_can.c                        | 1 -
 drivers/net/can/ti_hecc.c                          | 1 -
 drivers/net/can/usb/ems_usb.c                      | 2 --
 drivers/net/can/usb/esd_usb.c                      | 2 --
 drivers/net/can/usb/etas_es58x/es58x_core.c        | 1 -
 drivers/net/can/usb/f81604.c                       | 1 -
 drivers/net/can/usb/gs_usb.c                       | 1 -
 drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c   | 2 --
 drivers/net/can/usb/mcba_usb.c                     | 2 --
 drivers/net/can/usb/nct6694_canfd.c                | 1 -
 drivers/net/can/usb/peak_usb/pcan_usb_core.c       | 2 --
 drivers/net/can/usb/usb_8dev.c                     | 2 --
 drivers/net/can/virtio_can.c                       | 1 -
 drivers/net/can/xilinx_can.c                       | 2 --
 38 files changed, 7 insertions(+), 47 deletions(-)
---
base-commit: 828c4a5a9518117f9f7bdc445a7eeca85fc91bf8
change-id: 20260804-automate_iff_echo_flag-6ddd7f4def7a

Best regards,
-- 
Vincent Mailhol <mailhol@kernel.org>