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Commit 1a37e412 authored by Simon Horman's avatar Simon Horman Committed by David S. Miller
Browse files

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: default avatarSimon Horman <horms@verge.net.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 50ab731e

include/linux/skbuff.h

+6 −113
Original line number Diff line number Diff line
@@ -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)

{