/* SPDX-License-Identifier: GPL-2.0-or-later */ #ifndef _NET_GSO_H#define _NET_GSO_H #include <linux/skbuff.h> /* Keeps track of mac header offset relative to skb->head. * It is useful for TSO of Tunneling protocol. e.g. GRE. * For non-tunnel skb it points to skb_mac_header() and for * tunnel skb it points to outer mac header. * Keeps track of level of encapsulation of network headers. */struct skb_gso_cb {	union {		int	mac_offset;		int	data_offset;	};	int	encap_level;	__wsum	csum;	__u16	csum_start;};#define SKB_GSO_CB_OFFSET	32#define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_GSO_CB_OFFSET)) static inline int skb_tnl_header_len(const struct sk_buff *inner_skb){	return (skb_mac_header(inner_skb) - inner_skb->head) -		SKB_GSO_CB(inner_skb)->mac_offset;} static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra){	int new_headroom, headroom;	int ret; 	headroom = skb_headroom(skb);	ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);	if (ret)		return ret; 	new_headroom = skb_headroom(skb);	SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);	return 0;} static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res){	/* Do not update partial checksums if remote checksum is enabled. */	if (skb->remcsum_offload)		return; 	SKB_GSO_CB(skb)->csum = res;	SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;} /* Compute the checksum for a gso segment. First compute the checksum value * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and * then add in skb->csum (checksum from csum_start to end of packet). * skb->csum and csum_start are then updated to reflect the checksum of the * resultant packet starting from the transport header-- the resultant checksum * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo * header. */static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res){	unsigned char *csum_start = skb_transport_header(skb);	int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;	__wsum partial = SKB_GSO_CB(skb)->csum; 	SKB_GSO_CB(skb)->csum = res;	SKB_GSO_CB(skb)->csum_start = csum_start - skb->head; 	return csum_fold(csum_partial(csum_start, plen, partial));} struct sk_buff *__skb_gso_segment(struct sk_buff *skb,				  netdev_features_t features, bool tx_path); static inline struct sk_buff *skb_gso_segment(struct sk_buff *skb,					      netdev_features_t features){	return __skb_gso_segment(skb, features, true);} struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,				    netdev_features_t features, __be16 type); struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,				    netdev_features_t features); bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu); bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len); static inline void skb_gso_error_unwind(struct sk_buff *skb, __be16 protocol,					int pulled_hlen, u16 mac_offset,					int mac_len){	skb->protocol = protocol;	skb->encapsulation = 1;	skb_push(skb, pulled_hlen);	skb_reset_transport_header(skb);	skb->mac_header = mac_offset;	skb->network_header = skb->mac_header + mac_len;	skb->mac_len = mac_len;} #endif /* _NET_GSO_H */