[PATCH v2 net-next 0/2] ip: Batch flushing uncached routes per batched device unregistration.

[Kuniyuki Iwashima <kuniyu@google.com>]

Chris J Arges reported high RTNL contention during cleanup_net()
caused by rt_flush_dev() and rt6_uncached_list_flush_dev() iterating
over the global per-cpu uncached route lists for every netdev in
dying netns [0].

This series resolves the issue by batching the uncached route
cleanup after __rtnl_unlock() in netdev_run_todo().

[0]: https://lore.kernel.org/netdev/20260917-hash-bucket-route-lists-v3-0-30493a37b6eb@cloudflare.com/


Changelog:
  v2:
    * Drop ->pre_exit_batch()
    * Do batching after setting NETDEV_UNREGISTERED in netdev_run_todo()

  v1: https://lore.kernel.org/netdev/20260927202429.2452589-1-kuniyu@google.com/


Kuniyuki Iwashima (2):
  ipv4: Batch rt_flush_dev() in netdev_run_todo().
  ipv6: Batch rt6_uncached_list_flush_dev() in netdev_run_todo().

 include/net/ip6_route.h |  7 +++++++
 include/net/route.h     |  6 ++++++
 net/core/dev.c          |  5 +++++
 net/ipv4/route.c        | 11 +++++++++--
 net/ipv6/route.c        | 18 ++++++++++++++----
 5 files changed, 41 insertions(+), 6 deletions(-)

-- 
2.56.0.rc1.315.gc6ed9934b7-goog