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