target/linux/brcm2708/patches-4.14/950-0272-net-lan78xx-Reduce-s-w-csum-check-on-VLANs.patch

   1 From 126c6760f56d2d7a82c605a54c402a886ae9b5bf Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.org>
   3 Date: Tue, 10 Apr 2018 13:08:36 +0100
   4 Subject: [PATCH 272/454] net: lan78xx: Reduce s/w csum check on VLANs
   5
   6 With HW_VLAN_CTAG_RX enabled we don't observe the checksum
   7 issue, so amend the workaround to only drop back to s/w
   8 checksums if VLAN offload is disabled.
   9
  10 See #2458.
  11
  12 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
  13 ---
  14  drivers/net/usb/lan78xx.c | 7 ++++---
  15  1 file changed, 4 insertions(+), 3 deletions(-)
  16
  17 --- a/drivers/net/usb/lan78xx.c
  18 +++ b/drivers/net/usb/lan78xx.c
  19 @@ -2968,12 +2968,13 @@ static void lan78xx_rx_csum_offload(stru
  20                                     struct sk_buff *skb,
  21                                     u32 rx_cmd_a, u32 rx_cmd_b)
  22  {
  23 -       /* Checksum offload appears to be flawed if used with VLANs.
  24 -        * Elect for sw checksum check instead.
  25 +       /* HW Checksum offload appears to be flawed if used when not stripping
  26 +        * VLAN headers.
  27          */
  28         if (!(dev->net->features & NETIF_F_RXCSUM) ||
  29             unlikely(rx_cmd_a & RX_CMD_A_ICSM_) ||
  30 -           (rx_cmd_a & RX_CMD_A_FVTG_)) {
  31 +           ((rx_cmd_a & RX_CMD_A_FVTG_) &&
  32 +            !(dev->net->features & NETIF_F_HW_VLAN_CTAG_RX))) {
  33                 skb->ip_summed = CHECKSUM_NONE;
  34         } else {
  35                 skb->csum = ntohs((u16)(rx_cmd_b >> RX_CMD_B_CSUM_SHIFT_));