[PATCH iwl-net v4 0/2] idpf: destroy the vports on shutdown

[Tian Xun Ng <luckilystar08@gmail.com>]

From: Tian Xun Ng <tianxun.ng@bytedance.com>

On shutdown idpf shuts its virtchnl transaction manager down before the
vports are torn down, so the device is never told that they are gone.
Patch 2 keeps the mailbox up for that teardown, as remove already does,
with a short timeout so that an unresponsive control plane cannot hold
up a reboot for long. Doing so would expose shutdown to an existing
remove-path race between the async PTP Tx timestamp callback and
idpf_ptp_release(), which patch 1 closes first.

An LLM coding assistant helped analyse the problem and draft the changes
and their messages. Both patches carry an Assisted-by tag.

Changes in v4:
- New patch 1, closing the Tx timestamp callback race that Sashiko
  pointed out on v3. It already affects remove; with patch 2 it would
  also reach shutdown.
- Patch 2: the Tx queue SW marker wait follows the same bail-out as the
  mailbox transactions, so a control plane that acks DISABLE_QUEUES but
  posts no markers costs one marker timeout instead of one per queue
  (Emil).
- Patch 2: the statistics task stops sending once IDPF_REMOVE_IN_PROG is
  set (Emil).
- Patch 2: the shutdown comment now says that a transaction already in
  flight keeps its own timeout; bounding that would need support in
  libie.
- Not changed: if one teardown reply or Tx queue marker takes longer
  than 500 ms, the rest of the teardown is skipped. On the tested PFs
  the queue-related messages took at most 240 ms, and the slowest,
  DEALLOC_VECTORS (about 300 ms), is sent last, after DESTROY_VPORT.
  With the driver made to treat the first Tx queue marker as missing, so
  that UNMAP_QUEUE_VECTOR, DESTROY_VPORT and DEALLOC_VECTORS were
  skipped, 3 of 3 warm reboots were still clean on these devices. A
  function reset as a fallback was patch 2 of v1; in our tests a
  function reset on shutdown did not stop the faults, so it was dropped.
  I can add one for when the timeout fires if that is preferred.

Testing, besides what patch 2 describes: W=1 builds of idpf and libie
with allmodconfig and allyesconfig showed no new warnings after either
patch. On one server, modprobe -r idpf and a reload completed without
warnings or IOMMU faults. These devices do not support PTP, so the path
that patch 1 changes was not exercised on hardware.

Changes in v3:
- No new flags: adapter->vc_xn_timeout_ms (60 s from probe) is lowered
  to 500 ms on shutdown, and idpf_send_mb_msg() fails the rest at once
  after a shortened transaction times out (Emil).
- IDPF_REMOVE_IN_PROG is set before the service and event tasks are
  cancelled (Emil); the comment and message no longer state that a reset
  does not clear the vports (Emil).

v3: https://lore.kernel.org/all/20261009032706.94324-1-luckilystar08@gmail.com/
v2: https://lore.kernel.org/all/20261007055741.30629-1-luckilystar08@gmail.com/
v1: https://lore.kernel.org/all/20260917105205.37561-1-luckilystar08@gmail.com/

Tian Xun Ng (2):
  idpf: don't use the Tx timestamp trackers once removal has started
  idpf: keep the mailbox up while tearing down vports on shutdown

 drivers/net/ethernet/intel/idpf/idpf.h        |  3 +
 drivers/net/ethernet/intel/idpf/idpf_lib.c    |  3 +
 drivers/net/ethernet/intel/idpf/idpf_main.c   | 11 +++
 .../net/ethernet/intel/idpf/idpf_virtchnl.c   | 68 ++++++++++++++++---
 .../net/ethernet/intel/idpf/idpf_virtchnl.h   |  1 +
 .../ethernet/intel/idpf/idpf_virtchnl_ptp.c   |  3 +-
 6 files changed, 80 insertions(+), 9 deletions(-)

-- 
2.50.1 (Apple Git-155)