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net: macb: initialize checksum when using checksum offloading

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I'm still struggling to get this fix right..

Changes since v2:
 - do not blindly modify SKB contents according to Dave's legitimate
   objection

Changes since v1:
 - dropped disabling HW checksum offload for Zynq
 - initialize checksum similar to net/ethernet/freescale/fec_main.c

-- >8 --
MACB/GEM needs the checksum field initialized to 0 to get correct
results on transmit in all cases, e.g. on Zynq, UDP packets with
payload <= 2 otherwise contain a wrong checksums.

Signed-off-by: Helmut Buchsbaum <helmut.buchsbaum@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Helmut Buchsbaum 2016-09-04 18:09:47 +02:00 committed by David S. Miller
parent 03c2778a93
commit 007e4ba3ee
1 changed files with 23 additions and 0 deletions
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23
drivers/net/ethernet/cadence/macb.c
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@ -1323,6 +1323,24 @@ dma_error:
return 0;
}
static inline int macb_clear_csum(struct sk_buff *skb)
{
/* no change for packets without checksum offloading */
if (skb->ip_summed != CHECKSUM_PARTIAL)
return 0;
/* make sure we can modify the header */
if (unlikely(skb_cow_head(skb, 0)))
return -1;
/* initialize checksum field
* This is required - at least for Zynq, which otherwise calculates
* wrong UDP header checksums for UDP packets with UDP data len <=2
*/
*(__sum16 *)(skb_checksum_start(skb) + skb->csum_offset) = 0;
return 0;
}
static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
u16 queue_index = skb_get_queue_mapping(skb);
@ -1362,6 +1380,11 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
return NETDEV_TX_BUSY;
}
if (macb_clear_csum(skb)) {
dev_kfree_skb_any(skb);
return NETDEV_TX_OK;
}
/* Map socket buffer for DMA transfer */
if (!macb_tx_map(bp, queue, skb)) {
dev_kfree_skb_any(skb);