[PATCH RFC batadv v3 0/4] batman-adv: drop global hard interface list

The global hard interface list was used in the past to provide and sysfs
(debugfs, procfs) based configuration interface. This requirement is gone
after it was switched to generic netlink and NETLINK_ROUTE. And after the
wifi-flags cache was introduced, it is also no longer used to get
non-batman-adv attached interface information (for ap_isolation and
re-broadcast configuration).

But this odd net_devices list (batadv_hardif_list) stayed and caused some
headaches:

* memory requirement increased (useless) for each network interface of the
  system
* massive increase of various ethernet operations due to the O(n) nature of
  this global list
* the code had to handle switch of a batadv_hard_iface from one mesh_iface
  to either NULL or a different mesh_iface

Just get rid of it now and start to simplify the code around it.

This RFC is on purpose not Signed-off-by because I just want to restart the
discussion but didn't discuss this with the original author (nor documented
the changes in each patch in detail). And it is also not meant to look like
I've reviewed the changes and Ack it - this is unfortunately something
which I have to do again with this rebased version.

I will later post an range-diff which contains all the changes.

Signed-off-by: Sven Eckelmann <[email protected]>
---
Changes in v3:
- fix return kernel-doc for batadv_hardif_enable_interface
- drop merged first patch
- really switch to RFC
- in merged batadv_hardif_enable_interface (as intermediate step), only add
  the hard_iface to the batadv_hardif_list when hard_iface is really
  initialized
  + this list is dropped anyway with the patch "remove global hardif list"
- stop setting "mesh_iface" to NULL on error. it is now only important that
  the hard_iface gets unlinked from the mesh_iface
- first drop the batadv_hardif_list before removing the "safety" state
  BATADV_IF_NOT_IN_USE
- Link to v2: https://patch.msgid.link/[email protected]

Changes in v2:
- rebased
- submit as RFC to get the discussion started again
- drop already merged "batman-adv: store hard_iface as iflink private data"
- switch from kzalloc to kzalloc_obj
- update author's mail and name
- fix reference counting for batman_adv_ptype
- Link to v1: https://patch.msgid.link/0b26554afea5203820faef1dfb498af7533a9b5d.1747687504.git.mschiffer@universe-factory.net

---
Nora Schiffer (4):
      batman-adv: only create hardif while a netdev is part of a mesh
      batman-adv: remove global hardif list
      batman-adv: remove BATADV_IF_NOT_IN_USE hardif state
      batman-adv: move hardif generation counter into batadv_priv

 net/batman-adv/bat_iv_ogm.c     |   3 +-
 net/batman-adv/bat_v_elp.c      |   3 +-
 net/batman-adv/hard-interface.c | 146 +++++++++++++---------------------------
 net/batman-adv/hard-interface.h |  10 +--
 net/batman-adv/main.c           |   6 --
 net/batman-adv/main.h           |   3 -
 net/batman-adv/mesh-interface.c |  13 +---
 net/batman-adv/netlink.c        |   4 +-
 net/batman-adv/originator.c     |   4 --
 net/batman-adv/types.h          |   6 +-
 10 files changed, 59 insertions(+), 139 deletions(-)
---
base-commit: 7fb5fc7265f6ce4962357c5383873fd2ef9d50d4
change-id: 20260531-drop-hardif-list-bcf812da69dd

Best regards,
--  
Sven Eckelmann <[email protected]>