9 files changed, 13 insertions, 16 deletions

diff --git a/drivers/net/atlx/atl1.c b/drivers/net/atlx/atl1.c
index 53363108994e..def8df83359c 100644
--- a/drivers/net/atlx/atl1.c
+++ b/drivers/net/atlx/atl1.c
@@ -2174,7 +2174,7 @@ static int atl1_tx_csum(struct atl1_adapter *adapter, struct sk_buff *skb,
         u8 css, cso;
 
         if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
-                css = (u8) (skb->csum_start - skb_headroom(skb));
+                css = skb_checksum_start_offset(skb);
                 cso = css + (u8) skb->csum_offset;
                 if (unlikely(css & 0x1)) {
                         /* L1 hardware requires an even number here */
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 42567279843e..21845affea13 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -504,8 +504,7 @@ static int macvtap_skb_to_vnet_hdr(const struct sk_buff *skb,
 
         if (skb->ip_summed == CHECKSUM_PARTIAL) {
                 vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-                vnet_hdr->csum_start = skb->csum_start -
-                                        skb_headroom(skb);
+                vnet_hdr->csum_start = skb_checksum_start_offset(skb);
                 vnet_hdr->csum_offset = skb->csum_offset;
         } /* else everything is zero */
 
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 55f3a3e667a9..7599c457abd1 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -757,7 +757,7 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
 
                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
                         gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-                        gso.csum_start = skb->csum_start - skb_headroom(skb);
+                        gso.csum_start = skb_checksum_start_offset(skb);
                         gso.csum_offset = skb->csum_offset;
                 } /* else everything is zero */
 
diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c
index 65cb1abfbe57..bc86f4b6ecc2 100644
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -1163,9 +1163,8 @@ static int smsc95xx_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 
 static u32 smsc95xx_calc_csum_preamble(struct sk_buff *skb)
 {
-        int len = skb->data - skb->head;
-        u16 high_16 = (u16)(skb->csum_offset + skb->csum_start - len);
-        u16 low_16 = (u16)(skb->csum_start - len);
+        u16 low_16 = (u16)skb_checksum_start_offset(skb);
+        u16 high_16 = low_16 + skb->csum_offset;
         return (high_16 << 16) | low_16;
 }
 
@@ -1193,7 +1192,7 @@ static struct sk_buff *smsc95xx_tx_fixup(struct usbnet *dev,
                 if (skb->len <= 45) {
                         /* workaround - hardware tx checksum does not work
                          * properly with extremely small packets */
-                        long csstart = skb->csum_start - skb_headroom(skb);
+                        long csstart = skb_checksum_start_offset(skb);
                         __wsum calc = csum_partial(skb->data + csstart,
                                 skb->len - csstart, 0);
                         *((__sum16 *)(skb->data + csstart
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b6d402806ae6..90a23e410d1b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -519,7 +519,7 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
 
         if (skb->ip_summed == CHECKSUM_PARTIAL) {
                 hdr->hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-                hdr->hdr.csum_start = skb->csum_start - skb_headroom(skb);
+                hdr->hdr.csum_start = skb_checksum_start_offset(skb);
                 hdr->hdr.csum_offset = skb->csum_offset;
         } else {
                 hdr->hdr.flags = 0;
diff --git a/net/core/dev.c b/net/core/dev.c
index 794b20de5d44..92d414ac0e30 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1793,7 +1793,7 @@ int skb_checksum_help(struct sk_buff *skb)
                 goto out_set_summed;
         }
 
-        offset = skb->csum_start - skb_headroom(skb);
+        offset = skb_checksum_start_offset(skb);
         BUG_ON(offset >= skb_headlen(skb));
         csum = skb_checksum(skb, offset, skb->len - offset, 0);
 
@@ -2090,8 +2090,8 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
                          * checksumming here.
                          */
                         if (skb->ip_summed == CHECKSUM_PARTIAL) {
-                                skb_set_transport_header(skb, skb->csum_start -
-                                              skb_headroom(skb));
+                                skb_set_transport_header(skb,
+                                        skb_checksum_start_offset(skb));
                                 if (!dev_can_checksum(dev, skb) &&
                                      skb_checksum_help(skb))
                                         goto out_kfree_skb;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 8814a9a52f47..19d6c21220fd 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1824,7 +1824,7 @@ void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to)
         long csstart;
 
         if (skb->ip_summed == CHECKSUM_PARTIAL)
-                csstart = skb->csum_start - skb_headroom(skb);
+                csstart = skb_checksum_start_offset(skb);
         else
                 csstart = skb_headlen(skb);
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b37181da487c..1198adf45102 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2226,7 +2226,7 @@ struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, int features)
         /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
          * do checksum of UDP packets sent as multiple IP fragments.
          */
-        offset = skb->csum_start - skb_headroom(skb);
+        offset = skb_checksum_start_offset(skb);
         csum = skb_checksum(skb, offset, skb->len - offset, 0);
         offset += skb->csum_offset;
         *(__sum16 *)(skb->data + offset) = csum_fold(csum);
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index e79efaf06389..91cb1d71f018 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1650,8 +1650,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
 
                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
                         vnet_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-                        vnet_hdr.csum_start = skb->csum_start -
-                                                        skb_headroom(skb);
+                        vnet_hdr.csum_start = skb_checksum_start_offset(skb);
                         vnet_hdr.csum_offset = skb->csum_offset;
                 } /* else everything is zero */