RE: [PATCH] net: stmmac: skip VLAN restore when VLAN hash ops are missing

[Ovidiu Panait]

Hi Michal,

> stmmac_vlan_restore() unconditionally calls stmmac_vlan_update() when
> NETIF_F_VLAN_FEATURES is set. On platforms where priv->hw->vlan (or
> ->update_vlan_hash) is not provided, stmmac_update_vlan_hash() returns
> -EINVAL via stmmac_do_void_callback(), resulting in a spurious
> "Failed to restore VLANs" error even when no VLAN filtering is in use.
> 
> Check presence of VLAN hash ops before stmmac_vlan_update().
> 
> Fixes: bd7ad51253a7 ("net: stmmac: Fix VLAN HW state restore")
> Signed-off-by: Michal Piekos <michal.piekos@xxxxxxxxxxxxx>
> ---
> This patch fixes a noisy "Failed to restore VLANs" message on platforms
> where stmmac VLAN hash ops are not implemented.
> stmmac_vlan_restore() calls stmmac_vlan_update() without checking for
> VLAN hash ops presence which results in -EINVAL.
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 6827c99bde8c..bc09439ec00b 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -6869,6 +6869,9 @@ static int stmmac_vlan_restore(struct stmmac_priv
> *priv)
>         if (priv->hw->num_vlan)
>                 stmmac_restore_hw_vlan_rx_fltr(priv, priv->dev, priv->hw);
> 
> +       if (!priv->hw->vlan || !priv->hw->vlan->update_vlan_hash)
> +               return 0;
> +

The stmmac_restore_hw_vlan_rx_fltr() call above also goes through the
priv->hw->vlan pointer, so maybe for consistency, the check for empty
VLAN ops should be made at the top of the function.

Another alternative would be to replace the NETIF_F_VLAN_FEATURES check
at the top of stmmac_vlan_update() function to check if VLAN HW filtering
is supported instead (NETIF_F_HW_VLAN_CTAG_FILTER and
NETIF_F_HW_VLAN_STAG_FILTER).

The restore only deals with the HW filters anyway and the vlan ops are
always defined in that case (stmmac_vlan_rx_add_vid() and
stmmac_vlan_rx_kill_vid() rely on this being true as well, as they also
call stmmac_vlan_update() unconditionally).

Ovidiu

>         ret = stmmac_vlan_update(priv, priv->num_double_vlans);
>         if (ret)
>                 netdev_err(priv->dev, "Failed to restore VLANs\n");
> 
> ---
> base-commit: 1c9982b4961334c1edb0745a04cabd34bc2de675
> change-id: 20260314-vlan-restore-error-f8b3a1c7f50a
> 
> Best regards,
> --
> Michal Piekos <michal.piekos@xxxxxxxxxxxxx>