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net: Use 16bits for *_headers fields of struct skbuff
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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>
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Simon Horman authored and David S. Miller committed May 28, 2013
1 parent 50ab731 commit 1a37e41
Showing 1 changed file with 6 additions and 113 deletions.
119 changes: 6 additions & 113 deletions include/linux/skbuff.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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)
{
Expand Down Expand Up @@ -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)
{
Expand Down

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