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Commit 007e4ba3 authored by Helmut Buchsbaum's avatar Helmut Buchsbaum Committed by David S. Miller
Browse files

net: macb: initialize checksum when using checksum offloading 



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: default avatarHelmut Buchsbaum <helmut.buchsbaum@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 03c2778a

drivers/net/ethernet/cadence/macb.c

+23 −0
Original line number Diff line number Diff line
@@ -1323,6 +1323,24 @@ static unsigned int macb_tx_map(struct macb *bp, 
	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);