From: Enrico Pozzobon The hardware VLAN filter (RFE_CTL_VLAN_FILTER_) drops VLAN-tagged frames whose VID has not been registered via lan78xx_vlan_rx_add_vid(). It is left enabled in promiscuous mode, so packet capture (e.g. tcpdump or Wireshark) does not see tagged frames for unregistered VIDs. Clear the filter while the interface is promiscuous and restore it from NETIF_F_HW_VLAN_CTAG_FILTER otherwise. Enforce the same condition in lan78xx_set_features() so netdev_update_features() cannot re-enable the filter while promiscuous. Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver") Signed-off-by: Enrico Pozzobon --- Currently, on microchip lan7801, enabling promiscuous mode does not result in VLAN tagged packets being captured. This patch fixes this, forcing the RFE_CTL_VLAN_FILTER_ flag to be off when promiscuous mode is enabled. --- Changes in v2: - moved VLAN filter logic into lan78xx_update_vlan_filter() - Link to v1: https://patch.msgid.link/20260630-lan78xx-vlan-promisc-v1-1-fbf0f903bd8f@dissecto.com To: Thangaraj Samynathan To: Rengarajan Sundararajan To: UNGLinuxDriver@microchip.com To: Andrew Lunn To: "David S. Miller" To: Eric Dumazet To: Jakub Kicinski To: Paolo Abeni To: Woojung.Huh@microchip.com Cc: netdev@vger.kernel.org Cc: linux-usb@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- drivers/net/usb/lan78xx.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c index c4cebacabcb5..cb782d81d84f 100644 --- a/drivers/net/usb/lan78xx.c +++ b/drivers/net/usb/lan78xx.c @@ -1499,6 +1499,17 @@ static void lan78xx_deferred_multicast_write(struct work_struct *param) return; } +static void lan78xx_update_vlan_filter(struct lan78xx_priv *pdata, + struct net_device *netdev, + netdev_features_t features) +{ + if ((features & NETIF_F_HW_VLAN_CTAG_FILTER) && + !(netdev->flags & IFF_PROMISC)) + pdata->rfe_ctl |= RFE_CTL_VLAN_FILTER_; + else + pdata->rfe_ctl &= ~RFE_CTL_VLAN_FILTER_; +} + static void lan78xx_set_multicast(struct net_device *netdev) { struct lan78xx_net *dev = netdev_priv(netdev); @@ -1533,6 +1544,8 @@ static void lan78xx_set_multicast(struct net_device *netdev) } } + lan78xx_update_vlan_filter(pdata, dev->net, dev->net->features); + if (netdev_mc_count(dev->net)) { struct netdev_hw_addr *ha; int i; @@ -3074,10 +3087,7 @@ static int lan78xx_set_features(struct net_device *netdev, else pdata->rfe_ctl &= ~RFE_CTL_VLAN_STRIP_; - if (features & NETIF_F_HW_VLAN_CTAG_FILTER) - pdata->rfe_ctl |= RFE_CTL_VLAN_FILTER_; - else - pdata->rfe_ctl &= ~RFE_CTL_VLAN_FILTER_; + lan78xx_update_vlan_filter(pdata, netdev, features); spin_unlock_irqrestore(&pdata->rfe_ctl_lock, flags); --- base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482 change-id: 20260623-lan78xx-vlan-promisc-83af8a48a7ec Best regards, -- Enrico Pozzobon