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net: lan78xx: Request s/w csum check on VLAN tagged packets.

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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 <dave.stevenson@raspberrypi.org>
This commit is contained in:
Dave Stevenson
2018-04-09 14:31:54 +01:00
committed by Phil Elwell
parent bd16fc2ae6
commit 28aadd841d
1 changed files with 5 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/net/usb/lan78xx.c
View File

@@ -2973,8 +2973,12 @@ static void lan78xx_rx_csum_offload(struct lan78xx_net *dev,
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_));