[PATCH net-next v3 0/6] net: devmem: support leased RX and TX queues on netdev unregister

[Mina Almasry <almasrymina@google.com>]

Support leased RX and TX devmem bindings when either the virtual device
(e.g. netkit) or the physical backing net_device is unregistered:

1. Pass struct net_device **dev_ptr to net_devmem_lock_dev() so callers
   can lock either binding->map_dev or binding->bind_dev.
2. Rename binding->dev and binding->vdev to binding->map_dev (physical
   DMA device) and binding->bind_dev (device passed to bind-rx/bind-tx).
3. Introduce netif_lease_valid() and guard netif_mp_open_rxq(),
   netif_mp_close_rxq(), and netif_rxq_cleanup_unlease() against an
   unregistering physical device reached through a queue lease.
4. Always populate bind_dev on RX and TX bindings and handle teardown
   and netdev unregistration of both bind_dev and map_dev.
5. Resolve the physical backing map_dev in netdev_nl_get_dma_dev() for
   leased RX bindings, lock map_dev around net_devmem_bind_dmabuf() on
   bind-rx when map_dev differs from netdev, assert both devices are
   locked, and check netif_lease_valid(map_dev).
6. Add kselftests in nl_netdev.py covering leased RX and TX devmem
   bindings across both virtual-first and physical-first netdev
   unregistration orders.

v3:
- Rebase onto latest net-next/main.
- Add netif_lease_valid() helper and keep lease validity checks in the
  lease-aware callers (netif_mp_open_rxq(), netif_mp_close_rxq(),
  netif_rxq_cleanup_unlease(), and net_devmem_bind_dmabuf()) rather than
  inside __netif_mp_open_rxq() / __netif_mp_close_rxq(), and document why
  mp_params is cleared directly when !netif_lease_valid(dev) (Stanislav,
  Sashiko).
- Guard the bound_rxqs loop in net_devmem_unbind_dmabuf() with
  if (binding->bind_dev), keep the !netif_is_queue_leasee(dev) guard in
  net_devmem_dev_unregister() in patch 4/6 until patch 5/6 resolves
  binding->map_dev to the physical device so the series is bisectable at
  every commit, and document the use-after-free in dma_unmap_sg_attrs() on
  physical netdev teardown in patch 5/6 (Sashiko).
- In nl_netdev.py, verify dmabuf and lease on the physical queue after
  binding, skip when queue_create returns EOPNOTSUPP, probe the physical
  device on EOPNOTSUPP so a broken lease lookup is not masked as SKIP, and
  clean up nk_ifname between loop iterations (Sashiko).
- v2: https://lore.kernel.org/netdev/20261108055809.2122934-1-almasrymina@google.com/

v2:
- Split patch 3/4 from v1 into 3 smaller commits (patches 3/6..5/6).
- Clear rxq->mp_params and return 0 in __netif_mp_close_rxq() whenever
  dev is already unregistering, avoiding queue reconfiguration on an
  already-shut-down map_dev during cascaded lease teardown (Sashiko).
- Drop unnecessary xa_erase() in net_devmem_unbind_dmabuf() and use a
  local map_dev variable in net_devmem_get_binding() (Stanislav).
- Restore ASSERT_EXCLUSIVE_WRITER(binding->bind_dev) in
  mp_dmabuf_devmem_uninstall(), drop redundant bind_dev->reg_state check
  in net_devmem_bind_dmabuf(), and expand commit message rationale
  (Dragos, Stanislav).
- v1: https://lore.kernel.org/netdev/20261103232659.1340283-1-almasrymina@google.com/

Mina Almasry (6):
  net: devmem: pass net_device pointer to net_devmem_lock_dev()
  net: devmem: rename binding dev and vdev to map_dev and bind_dev
  net: guard memory provider RX queue open and close on unregister
  net: devmem: always populate bind_dev and detach both devices on
    unregister
  net: devmem: resolve physical map_dev for leased RX bindings
  selftests: net: add leased devmem RX and TX netdev unregister tests

 net/core/dev.c                           |   2 +-
 net/core/dev.h                           |   7 +
 net/core/devmem.c                        | 123 ++++++++++--------
 net/core/devmem.h                        |  25 ++--
 net/core/netdev-genl.c                   |  58 +++++----
 net/core/netdev_rx_queue.c               |  31 ++++-
 tools/testing/selftests/net/nl_netdev.py | 159 ++++++++++++++++++++++-
 7 files changed, 304 insertions(+), 101 deletions(-)


base-commit: 6964ff21c5d8b75649211a52dbfd92753e605649
-- 
2.56.0.611.g1030f0b940-goog