[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>

9 files changed, 49 insertions, 17 deletions

diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c
index ce3ed67a878e..0f4f76fda26f 100644
--- a/drivers/net/bnx2.c
+++ b/drivers/net/bnx2.c
@@ -6490,10 +6490,10 @@ bnx2_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         memcpy(dev->perm_addr, bp->mac_addr, 6);
         bp->name = board_info[ent->driver_data].name;
 
+        dev->features |= NETIF_F_IP_CSUM | NETIF_F_SG;
         if (CHIP_NUM(bp) == CHIP_NUM_5709)
-                dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
-        else
-                dev->features |= NETIF_F_IP_CSUM | NETIF_F_SG;
+                dev->features |= NETIF_F_IPV6_CSUM;
+
 #ifdef BCM_VLAN
         dev->features |= NETIF_F_HW_VLAN_TX | NETIF_F_HW_VLAN_RX;
 #endif
diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index 2f3184184ad9..3a43426ced32 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -11944,12 +11944,11 @@ static int __devinit tg3_init_one(struct pci_dev *pdev,
          * checksumming.
          */
         if ((tp->tg3_flags & TG3_FLAG_BROKEN_CHECKSUMS) == 0) {
+                dev->features |= NETIF_F_IP_CSUM | NETIF_F_SG;
                 if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5755 ||
                     GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5787)
-                        dev->features |= NETIF_F_HW_CSUM;
-                else
-                        dev->features |= NETIF_F_IP_CSUM;
-                dev->features |= NETIF_F_SG;
+                        dev->features |= NETIF_F_IPV6_CSUM;
+
                 tp->tg3_flags |= TG3_FLAG_RX_CHECKSUMS;
         } else
                 tp->tg3_flags &= ~TG3_FLAG_RX_CHECKSUMS;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e7913ee5581c..7a8f22fb4eee 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -314,9 +314,10 @@ struct net_device
         /* Net device features */
         unsigned long           features;
 #define NETIF_F_SG              1       /* Scatter/gather IO. */
-#define NETIF_F_IP_CSUM         2       /* Can checksum only TCP/UDP over IPv4. */
+#define NETIF_F_IP_CSUM         2       /* Can checksum TCP/UDP over IPv4. */
 #define NETIF_F_NO_CSUM         4       /* Does not require checksum. F.e. loopack. */
 #define NETIF_F_HW_CSUM         8       /* Can checksum all the packets. */
+#define NETIF_F_IPV6_CSUM       16      /* Can checksum TCP/UDP over IPV6 */
 #define NETIF_F_HIGHDMA         32      /* Can DMA to high memory. */
 #define NETIF_F_FRAGLIST        64      /* Scatter/gather IO. */
 #define NETIF_F_HW_VLAN_TX      128     /* Transmit VLAN hw acceleration */
@@ -338,8 +339,11 @@ struct net_device
         /* List of features with software fallbacks. */
 #define NETIF_F_GSO_SOFTWARE    (NETIF_F_TSO | NETIF_F_TSO_ECN | NETIF_F_TSO6)
 
+
 #define NETIF_F_GEN_CSUM        (NETIF_F_NO_CSUM | NETIF_F_HW_CSUM)
-#define NETIF_F_ALL_CSUM        (NETIF_F_IP_CSUM | NETIF_F_GEN_CSUM)
+#define NETIF_F_V4_CSUM         (NETIF_F_GEN_CSUM | NETIF_F_IP_CSUM)
+#define NETIF_F_V6_CSUM         (NETIF_F_GEN_CSUM | NETIF_F_IPV6_CSUM)
+#define NETIF_F_ALL_CSUM        (NETIF_F_V4_CSUM | NETIF_F_V6_CSUM)
 
         struct net_device       *next_sched;
 
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 &