From 44136672c6043943bcf0772bb0edfb6fc23354dc Mon Sep 17 00:00:00 2001 From: Dave Stevenson Date: Mon, 9 Apr 2018 14:31:54 +0100 Subject: [PATCH 269/454] net: lan78xx: Request s/w csum check on VLAN tagged packets. There appears to be some issue in the LAN78xx where the checksum computed on a VLAN tagged packet is incorrect, or at least not in the form that the kernel is after. This is most easily shown by pinging a device via a VLAN tagged interface and it will dump out the error message and stack trace from netdev_rx_csum_fault. It has also been seen with standard TCP and UDP packets. Until this is fully understood, request that the network stack computes the checksum on packets signalled as having a VLAN tag applied. See https://github.com/raspberrypi/linux/issues/2458 Signed-off-by: Dave Stevenson --- drivers/net/usb/lan78xx.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/net/usb/lan78xx.c +++ b/drivers/net/usb/lan78xx.c @@ -2959,8 +2959,12 @@ static void lan78xx_rx_csum_offload(stru struct sk_buff *skb, u32 rx_cmd_a, u32 rx_cmd_b) { + /* Checksum offload appears to be flawed if used with VLANs. + * Elect for sw checksum check instead. + */ if (!(dev->net->features & NETIF_F_RXCSUM) || - unlikely(rx_cmd_a & RX_CMD_A_ICSM_)) { + unlikely(rx_cmd_a & RX_CMD_A_ICSM_) || + (rx_cmd_a & RX_CMD_A_FVTG_)) { skb->ip_summed = CHECKSUM_NONE; } else { skb->csum = ntohs((u16)(rx_cmd_b >> RX_CMD_B_CSUM_SHIFT_));