In order to exercise and verify notifiers' locking assumptions,
register dummy notifiers (via register_netdevice_notifier_dev_net).
Share notifier event handler that enforces the assumptions with
lock_debug.c (rename and export rtnl_net_debug_event as
netdev_debug_event). Add ops lock asserts to netdev_debug_event.

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250401163452.622454-6-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Steffen Klassert says:

====================
pull request (net-next): ipsec-next 2025-03-24

1) Prevent setting high order sequence number bits input in
   non-ESN mode. From Leon Romanovsky.

2) Support PMTU handling in tunnel mode for packet offload.
   From Leon Romanovsky.

3) Make xfrm_state_lookup_byaddr lockless.
   From Florian Westphal.

4) Remove unnecessary NULL check in xfrm_lookup_with_ifid().
   From Dan Carpenter.

* tag 'ipsec-next-2025-03-24' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next:
  xfrm: Remove unnecessary NULL check in xfrm_lookup_with_ifid()
  xfrm: state: make xfrm_state_lookup_byaddr lockless
  xfrm: check for PMTU in tunnel mode for packet offload
  xfrm: provide common xdo_dev_offload_ok callback implementation
  xfrm: rely on XFRM offload
  xfrm: simplify SA initialization routine
  xfrm: delay initialization of offload path till its actually requested
  xfrm: prevent high SEQ input in non-ESN mode
====================

Link: https://patch.msgid.link/20250324061855.4116819-1-steffen.klassert@secunet.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Almost all drivers except bond and nsim had same check if device
can perform XFRM offload on that specific packet. The check was that
packet doesn't have IPv4 options and IPv6 extensions.

In NIC drivers, the IPv4 HELEN comparison was slightly different, but
the intent was to check for the same conditions. So let's chose more
strict variant as a common base.

Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

The netdevsim driver was experiencing NOHZ tick-stop errors during packet
transmission due to pending softirq work when calling napi_schedule().
This issue was observed when running the netconsole selftest, which
triggered the following error message:

  NOHZ tick-stop error: local softirq work is pending, handler #08!!!

To fix this issue, introduce a timer that schedules napi_schedule()
from a timer context instead of calling it directly from the TX path.

Create an hrtimer for each queue and kick it from the TX path,
which then schedules napi_schedule() from the timer context.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20250219-netdevsim-v3-1-811e2b8abc4c@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

syzbot discovered that we remove the debugfs files after we free
the netdev. Try to clean up the relevant dir while the device
is still around.

Reported-by: syzbot+2e5de9e3ab986b71d2bf@syzkaller.appspotmail.com
Fixes: 424be63ad831 ("netdevsim: add UDP tunnel port offload support")
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Link: https://patch.msgid.link/20250122224503.762705-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

HDS options(tcp-data-split, hds-thresh) have dependencies between other
features like XDP. Basic dependencies are checked in the core API.
netdevsim is very useful to check basic dependencies.

The default tcp-data-split mode is UNKNOWN but netdevsim driver
returns ENABLED when ethtool dumps tcp-data-split mode.
The default value of HDS threshold is 0 and the maximum value is 1024.

ethtool shows like this.

ethtool -g eni1np1
Ring parameters for eni1np1:
Pre-set maximums:
...
HDS thresh:             1024
Current hardware settings:
...
TCP data split:         on
HDS thresh:             0

ethtool -G eni1np1 tcp-data-split on hds-thresh 1024
ethtool -g eni1np1
Ring parameters for eni1np1:
Pre-set maximums:
...
HDS thresh:             1024
Current hardware settings:
...
TCP data split:         on
HDS thresh:             1024

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://patch.msgid.link/20250114142852.3364986-10-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Support triggering queue reset via debugfs for an upcoming test.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Add queue management API support. We need a way to reset queues
to test NAPI reordering, the queue management API provides a
handy scaffolding for that.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Make nsim->rqs an array of pointers and allocate them individually
so that we can swap them out one by one.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Add NAPI support to netdevim, similar to veth.

* Add a nsim_rq rx queue structure to hold a NAPI instance and a skb
  queue.
* During xmit, store the skb in the peer skb queue and schedule NAPI.
* During napi_poll(), drain the skb queue and pass up the stack.
* Add assoc between rxq and NAPI instance using netif_queue_set_napi().

Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://lore.kernel.org/r/20240507163228.2066817-2-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>