linux/include/net/gso.h

/* 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 { … };
#define SKB_GSO_CB_OFFSET …
#define SKB_GSO_CB(skb) …

static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
{ … }

static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
{ … }

static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
{ … }

/* 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)
{ … }

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)
{ … }

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)
{ … }

#endif /* _NET_GSO_H */