[NET]: IPV6 checksum offloading in network devices

The existing model for checksum offload does not correctly handle
devices that can offload IPV4 and IPV6 only. The NETIF_F_HW_CSUM flag
implies device can do any arbitrary protocol.

This patch:
 * adds NETIF_F_IPV6_CSUM for those devices
 * fixes bnx2 and tg3 devices that need it
 * add NETIF_F_IPV6_CSUM to ipv6 output (incl GSO)
 * fixes assumptions about NETIF_F_ALL_CSUM in nat
 * adjusts bridge union of checksumming computation

Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 37 insertions, 8 deletions

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 849deaf14108..7b4ce9113be2 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -368,10 +368,18 @@ void br_features_recompute(struct net_bridge *br)
         list_for_each_entry(p, &br->port_list, list) {
                 unsigned long feature = p->dev->features;
 
+                /* if device needs checksumming, downgrade to hw checksumming */
                 if (checksum & NETIF_F_NO_CSUM && !(feature & NETIF_F_NO_CSUM))
                         checksum ^= NETIF_F_NO_CSUM | NETIF_F_HW_CSUM;
+
+                /* if device can't do all checksum, downgrade to ipv4/ipv6 */
                 if (checksum & NETIF_F_HW_CSUM && !(feature & NETIF_F_HW_CSUM))
-                        checksum ^= NETIF_F_HW_CSUM | NETIF_F_IP_CSUM;
+                        checksum ^= NETIF_F_HW_CSUM
+                                | NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
+
+                if (checksum & NETIF_F_IPV6_CSUM && !(feature & NETIF_F_IPV6_CSUM))
+                        checksum &= ~NETIF_F_IPV6_CSUM;
+
                 if (!(feature & NETIF_F_IP_CSUM))
                         checksum = 0;
 
diff --git a/net/core/dev.c b/net/core/dev.c
index ee051bb398a0..a0a46e7ed137 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1509,9 +1509,11 @@ int dev_queue_xmit(struct sk_buff *skb)
                 skb_set_transport_header(skb, skb->csum_start -
                                               skb_headroom(skb));
 
-                if (!(dev->features & NETIF_F_GEN_CSUM) &&
-                    (!(dev->features & NETIF_F_IP_CSUM) ||
-                     skb->protocol != htons(ETH_P_IP)))
+                if (!(dev->features & NETIF_F_GEN_CSUM)
+                    || ((dev->features & NETIF_F_IP_CSUM)
+                        && skb->protocol == htons(ETH_P_IP))
+                    || ((dev->features & NETIF_F_IPV6_CSUM)
+                        && skb->protocol == htons(ETH_P_IPV6)))
                         if (skb_checksum_help(skb))
                                 goto out_kfree_skb;
         }
@@ -3107,6 +3109,22 @@ int register_netdevice(struct net_device *dev)
                 }
         }
 
+        /* Fix illegal checksum combinations */
+        if ((dev->features & NETIF_F_HW_CSUM) &&
+            (dev->features & (NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
+                printk(KERN_NOTICE "%s: mixed HW and IP checksum settings.\n",
+                       dev->name);
+                dev->features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
+        }
+
+        if ((dev->features & NETIF_F_NO_CSUM) &&
+            (dev->features & (NETIF_F_HW_CSUM|NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
+                printk(KERN_NOTICE "%s: mixed no checksumming and other settings.\n",
+                       dev->name);
+                dev->features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM|NETIF_F_HW_CSUM);
+        }
+
+
         /* Fix illegal SG+CSUM combinations. */
         if ((dev->features & NETIF_F_SG) &&
             !(dev->features & NETIF_F_ALL_CSUM)) {
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 041fba3fa0aa..06c08e5740fb 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1170,6 +1170,9 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb, int features)
         int ihl;
         int id;
 
+        if (!(features & NETIF_F_V4_CSUM))
+                features &= ~NETIF_F_SG;
+
         if (unlikely(skb_shinfo(skb)->gso_type &
                      ~(SKB_GSO_TCPV4 |
                        SKB_GSO_UDP |
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 34ea4547ebbe..a7dd343d3a03 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -837,7 +837,7 @@ int ip_append_data(struct sock *sk,
          */
         if (transhdrlen &&
             length + fragheaderlen <= mtu &&
-            rt->u.dst.dev->features & NETIF_F_ALL_CSUM &&
+            rt->u.dst.dev->features & NETIF_F_V4_CSUM &&
             !exthdrlen)
                 csummode = CHECKSUM_PARTIAL;
 
diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c
index 15b6e5ce3a04..b1aa5983a95b 100644
--- a/net/ipv4/netfilter/nf_nat_helper.c
+++ b/net/ipv4/netfilter/nf_nat_helper.c
@@ -178,7 +178,7 @@ nf_nat_mangle_tcp_packet(struct sk_buff **pskb,
         datalen = (*pskb)->len - iph->ihl*4;
         if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) {
                 if (!(rt->rt_flags & RTCF_LOCAL) &&
-                    (*pskb)->dev->features & NETIF_F_ALL_CSUM) {
+                    (*pskb)->dev->features & NETIF_F_V4_CSUM) {
                         (*pskb)->ip_summed = CHECKSUM_PARTIAL;
                         (*pskb)->csum_start = skb_headroom(*pskb) +
                                               skb_network_offset(*pskb) +
@@ -265,7 +265,7 @@ nf_nat_mangle_udp_packet(struct sk_buff **pskb,
 
         if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) {
                 if (!(rt->rt_flags & RTCF_LOCAL) &&
-                    (*pskb)->dev->features & NETIF_F_ALL_CSUM) {
+                    (*pskb)->dev->features & NETIF_F_V4_CSUM) {
                         (*pskb)->ip_summed = CHECKSUM_PARTIAL;
                         (*pskb)->csum_start = skb_headroom(*pskb) +
                                               skb_network_offset(*pskb) +
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index b636c38411fb..1c3506696cb5 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -123,7 +123,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb, int features)
         struct ipv6hdr *ipv6h;
         struct inet6_protocol *ops;
 
-        if (!(features & NETIF_F_HW_CSUM))
+        if (!(features & NETIF_F_V6_CSUM))
                 features &= ~NETIF_F_SG;
 
         if (unlikely(skb_shinfo(skb)->gso_type &