net: Use 16bits for *_headers fields of struct skbuff

In order to mitigate ongoing incresase in the size of struct skbuff
use 16 bit integer offsets rather than pointers for inner_*_headers.

This appears to reduce the size of struct skbuff from 0xd0 to 0xc0
bytes on x86_64 with the following all unset.

	CONFIG_XFRM
	CONFIG_NF_CONNTRACK
	CONFIG_NF_CONNTRACK_MODULE
	NET_SKBUFF_NF_DEFRAG_NEEDED
	CONFIG_BRIDGE_NETFILTER
	CONFIG_NET_SCHED
	CONFIG_IPV6_NDISC_NODETYPE
	CONFIG_NET_DMA
	CONFIG_NETWORK_SECMARK

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 113 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2e0ced1af3b1..5663e3592784 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -509,12 +509,12 @@ struct sk_buff {
                 __u32           reserved_tailroom;
         };
 
-        sk_buff_data_t          inner_transport_header;
-        sk_buff_data_t          inner_network_header;
-        sk_buff_data_t          inner_mac_header;
-        sk_buff_data_t          transport_header;
-        sk_buff_data_t          network_header;
-        sk_buff_data_t          mac_header;
+        __u16                   inner_transport_header;
+        __u16                   inner_network_header;
+        __u16                   inner_mac_header;
+        __u16                   transport_header;
+        __u16                   network_header;
+        __u16                   mac_header;
         /* These elements must be at the end, see alloc_skb() for details.  */
         sk_buff_data_t          tail;
         sk_buff_data_t          end;
@@ -1527,7 +1527,6 @@ static inline void skb_reset_mac_len(struct sk_buff *skb)
         skb->mac_len = skb->network_header - skb->mac_header;
 }
 
-#ifdef NET_SKBUFF_DATA_USES_OFFSET
 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
                                                         *skb)
 {
@@ -1638,112 +1637,6 @@ static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
         skb->mac_header += offset;
 }
 
-#else /* NET_SKBUFF_DATA_USES_OFFSET */
-static inline unsigned char *skb_inner_transport_header(const struct sk_buff
-                                                        *skb)
-{
-        return skb->inner_transport_header;
-}
-
-static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
-{
-        skb->inner_transport_header = skb->data;
-}
-
-static inline void skb_set_inner_transport_header(struct sk_buff *skb,
-                                                   const int offset)
-{
-        skb->inner_transport_header = skb->data + offset;
-}
-
-static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
-{
-        return skb->inner_network_header;
-}
-
-static inline void skb_reset_inner_network_header(struct sk_buff *skb)
-{
-        skb->inner_network_header = skb->data;
-}
-
-static inline void skb_set_inner_network_header(struct sk_buff *skb,
-                                                const int offset)
-{
-        skb->inner_network_header = skb->data + offset;
-}
-
-static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
-{
-        return skb->inner_mac_header;
-}
-
-static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
-{
-        skb->inner_mac_header = skb->data;
-}
-
-static inline void skb_set_inner_mac_header(struct sk_buff *skb,
-                                                const int offset)
-{
-        skb->inner_mac_header = skb->data + offset;
-}
-static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
-{
-        return skb->transport_header != NULL;
-}
-
-static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
-{
-        return skb->transport_header;
-}
-
-static inline void skb_reset_transport_header(struct sk_buff *skb)
-{
-        skb->transport_header = skb->data;
-}
-
-static inline void skb_set_transport_header(struct sk_buff *skb,
-                                            const int offset)
-{
-        skb->transport_header = skb->data + offset;
-}
-
-static inline unsigned char *skb_network_header(const struct sk_buff *skb)
-{
-        return skb->network_header;
-}
-
-static inline void skb_reset_network_header(struct sk_buff *skb)
-{
-        skb->network_header = skb->data;
-}
-
-static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
-{
-        skb->network_header = skb->data + offset;
-}
-
-static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
-{
-        return skb->mac_header;
-}
-
-static inline int skb_mac_header_was_set(const struct sk_buff *skb)
-{
-        return skb->mac_header != NULL;
-}
-
-static inline void skb_reset_mac_header(struct sk_buff *skb)
-{
-        skb->mac_header = skb->data;
-}
-
-static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
-{
-        skb->mac_header = skb->data + offset;
-}
-#endif /* NET_SKBUFF_DATA_USES_OFFSET */
-
 static inline void skb_probe_transport_header(struct sk_buff *skb,
                                               const int offset_hint)
 {