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Commit e0ce4af9 authored by Ian Campbell's avatar Ian Campbell Committed by David S. Miller
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xen: netfront: handle incoming GSO SKBs which are not CHECKSUM_PARTIAL 



The Linux network stack expects all GSO SKBs to have ip_summed ==
CHECKSUM_PARTIAL (which implies that the frame contains a partial
checksum) and the Xen network ring protocol similarly expects an SKB
which has GSO set to also have NETRX_csum_blank (which also implies a
partial checksum).

However there have been cases of buggy guests which mark a frame as
GSO but do not set csum_blank. If we detect that we a receiving such a
frame (which manifests as ip_summed != PARTIAL && skb_is_gso) then
force the SKB to partial and recalculate the checksum, since we cannot
rely on the peer having done so if they have not set csum_blank.

Add an ethtool stat to track occurances of this event.

Signed-off-by: default avatarIan Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David Miller <davem@davemloft.net>
Cc: xen-devel@lists.xensource.com
Cc: netdev@vger.kernel.org
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 389f2a18

drivers/net/xen-netfront.c

+88 −8
Original line number Diff line number Diff line
@@ -120,6 +120,9 @@ struct netfront_info { 
	unsigned long rx_pfn_array[NET_RX_RING_SIZE];

	struct multicall_entry rx_mcl[NET_RX_RING_SIZE+1];

	struct mmu_update rx_mmu[NET_RX_RING_SIZE];



	/* Statistics */

	int rx_gso_checksum_fixup;

};



struct netfront_rx_info {
@@ -770,11 +773,29 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np, 
	return cons;

}



static int skb_checksum_setup(struct sk_buff *skb)

static int checksum_setup(struct net_device *dev, struct sk_buff *skb)

{

	struct iphdr *iph;

	unsigned char *th;

	int err = -EPROTO;

	int recalculate_partial_csum = 0;



	/*

	 * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy

	 * peers can fail to set NETRXF_csum_blank when sending a GSO

	 * frame. In this case force the SKB to CHECKSUM_PARTIAL and

	 * recalculate the partial checksum.

	 */

	if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {

		struct netfront_info *np = netdev_priv(dev);

		np->rx_gso_checksum_fixup++;

		skb->ip_summed = CHECKSUM_PARTIAL;

		recalculate_partial_csum = 1;

	}



	/* A non-CHECKSUM_PARTIAL SKB does not require setup. */

	if (skb->ip_summed != CHECKSUM_PARTIAL)

		return 0;



	if (skb->protocol != htons(ETH_P_IP))

		goto out;
@@ -788,9 +809,23 @@ static int skb_checksum_setup(struct sk_buff *skb) 
	switch (iph->protocol) {

	case IPPROTO_TCP:

		skb->csum_offset = offsetof(struct tcphdr, check);



		if (recalculate_partial_csum) {

			struct tcphdr *tcph = (struct tcphdr *)th;

			tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,

							 skb->len - iph->ihl*4,

							 IPPROTO_TCP, 0);

		}

		break;

	case IPPROTO_UDP:

		skb->csum_offset = offsetof(struct udphdr, check);



		if (recalculate_partial_csum) {

			struct udphdr *udph = (struct udphdr *)th;

			udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,

							 skb->len - iph->ihl*4,

							 IPPROTO_UDP, 0);

		}

		break;

	default:

		if (net_ratelimit())
@@ -829,14 +864,12 @@ static int handle_incoming_queue(struct net_device *dev, 
		/* Ethernet work: Delayed to here as it peeks the header. */

		skb->protocol = eth_type_trans(skb, dev);



		if (skb->ip_summed == CHECKSUM_PARTIAL) {

			if (skb_checksum_setup(skb)) {

		if (checksum_setup(dev, skb)) {

			kfree_skb(skb);

			packets_dropped++;

			dev->stats.rx_errors++;

			continue;

		}

		}



		dev->stats.rx_packets++;

		dev->stats.rx_bytes += skb->len;
@@ -1632,12 +1665,59 @@ static void netback_changed(struct xenbus_device *dev, 
	}

}



static const struct xennet_stat {

	char name[ETH_GSTRING_LEN];

	u16 offset;

} xennet_stats[] = {

	{

		"rx_gso_checksum_fixup",

		offsetof(struct netfront_info, rx_gso_checksum_fixup)

	},

};



static int xennet_get_sset_count(struct net_device *dev, int string_set)

{

	switch (string_set) {

	case ETH_SS_STATS:

		return ARRAY_SIZE(xennet_stats);

	default:

		return -EINVAL;

	}

}



static void xennet_get_ethtool_stats(struct net_device *dev,

				     struct ethtool_stats *stats, u64 * data)

{

	void *np = netdev_priv(dev);

	int i;



	for (i = 0; i < ARRAY_SIZE(xennet_stats); i++)

		data[i] = *(int *)(np + xennet_stats[i].offset);

}



static void xennet_get_strings(struct net_device *dev, u32 stringset, u8 * data)

{

	int i;



	switch (stringset) {

	case ETH_SS_STATS:

		for (i = 0; i < ARRAY_SIZE(xennet_stats); i++)

			memcpy(data + i * ETH_GSTRING_LEN,

			       xennet_stats[i].name, ETH_GSTRING_LEN);

		break;

	}

}



static const struct ethtool_ops xennet_ethtool_ops =

{

	.set_tx_csum = ethtool_op_set_tx_csum,

	.set_sg = xennet_set_sg,

	.set_tso = xennet_set_tso,

	.get_link = ethtool_op_get_link,



	.get_sset_count = xennet_get_sset_count,

	.get_ethtool_stats = xennet_get_ethtool_stats,

	.get_strings = xennet_get_strings,

};



#ifdef CONFIG_SYSFS