> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf Of 
> Maciej Fijalkowski
> Sent: Thursday, April 16, 2026 4:41 AM
> To: [email protected]
> Cc: [email protected]; Karlsson, Magnus <[email protected]>; 
> [email protected]; [email protected]; [email protected]; Kitszel, Przemyslaw 
> <[email protected]>; Keller, > Jacob E <[email protected]>; 
> Fijalkowski, Maciej <[email protected]>
> Subject: [Intel-wired-lan] [PATCH v2 iwl-net] i40e: keep q_vectors array in 
> sync with channel count changes
>
> For the main VSI, i40e_set_num_rings_in_vsi() always derives
> num_q_vectors from pf->num_lan_msix. At the same time, ethtool -L stores
> the user requested channel count in vsi->req_queue_pairs and the queue
> setup path uses that value for the effective number of queue pairs.
>
> This leaves queue and vector counts out of sync after shrinking channel
> count via ethtool -L. The active queue configuration is reduced, but the
> VSI still keeps the full PF-sized q_vector topology.
>
> That mismatch breaks reconfiguration flows which rely on vector/NAPI
> state matching the effective channel configuration. In particular,
> toggling /sys/class/net/<dev>/threaded after reducing the channel count
> can hang, and later channel-count changes can fail because VSI reinit
> does not rebuild q_vectors to match the new vector count.
>
> Fix this by making the main VSI num_q_vectors follow the effective
> requested channel count, capped by the available MSI-X vectors. Update
> i40e_vsi_reinit_setup() to rebuild q_vectors during VSI reinit so the
> vector topology is refreshed together with the ring arrays when channel
> count changes.
>
> Keep alloc_queue_pairs unchanged and based on pf->num_lan_qps so the VSI
> retains its full queue capacity.
>
> Selftest napi_threaded.py was originally used when Jakub reported hang
> on /sys/class/net/<dev>/threaded toggle. In order to make it pass on
> i40e, use persistent NAPI configuration for q_vector NAPIs so NAPI
> identity and threaded settings survive q_vector reallocation across
> channel-count changes. This is achieved by using netif_napi_add_config()
> when configuring q_vectors.
>
> $ export NETIF=ens259f1np1
> $ sudo -E env PATH="$PATH" 
> ./tools/testing/selftests/drivers/net/napi_threaded.py
> TAP version 13
> 1..3
> ok 1 napi_threaded.napi_init
> ok 2 napi_threaded.change_num_queues
> ok 3 napi_threaded.enable_dev_threaded_disable_napi_threaded
> Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> Reported-by: Jakub Kicinski <[email protected]>
> Closes: 
> https://lore.kernel.org/intel-wired-lan/[email protected]/
> Fixes: d2a69fefd756 ("i40e: Fix changing previously set num_queue_pairs for 
> PFs")
> Signed-off-by: Maciej Fijalkowski <[email protected]>
> ---
> v2:
> - NULL vsi->tx_rings in i40e_vsi_alloc_arrays() (Sashiko)
> ---
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 35 +++++++++++++++++----
>  1 file changed, 29 insertions(+), 6 deletions(-)

Tested-by: Sunitha Mekala <[email protected]> (A Contingent worker at 
Intel)

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