original_kernel/net/mpls/internal.h

#ifndef MPLS_INTERNAL_H
#define MPLS_INTERNAL_H
#include <net/mpls.h>

/* put a reasonable limit on the number of labels
 * we will accept from userspace
 */
#define MAX_NEW_LABELS 30

struct mpls_entry_decoded {
	u32 label;
	u8 ttl;
	u8 tc;
	u8 bos;
};

struct mpls_pcpu_stats {
	struct mpls_link_stats	stats;
	struct u64_stats_sync	syncp;
};

struct mpls_dev {
	int				input_enabled;
	struct net_device		*dev;
	struct mpls_pcpu_stats __percpu	*stats;

	struct ctl_table_header		*sysctl;
	struct rcu_head			rcu;
};

#if BITS_PER_LONG == 32

#define MPLS_INC_STATS_LEN(mdev, len, pkts_field, bytes_field)		\
	do {								\
		__typeof__(*(mdev)->stats) *ptr =			\
			raw_cpu_ptr((mdev)->stats);			\
		local_bh_disable();					\
		u64_stats_update_begin(&ptr->syncp);			\
		ptr->stats.pkts_field++;				\
		ptr->stats.bytes_field += (len);			\
		u64_stats_update_end(&ptr->syncp);			\
		local_bh_enable();					\
	} while (0)

#define MPLS_INC_STATS(mdev, field)					\
	do {								\
		__typeof__(*(mdev)->stats) *ptr =			\
			raw_cpu_ptr((mdev)->stats);			\
		local_bh_disable();					\
		u64_stats_update_begin(&ptr->syncp);			\
		ptr->stats.field++;					\
		u64_stats_update_end(&ptr->syncp);			\
		local_bh_enable();					\
	} while (0)

#else

#define MPLS_INC_STATS_LEN(mdev, len, pkts_field, bytes_field)		\
	do {								\
		this_cpu_inc((mdev)->stats->stats.pkts_field);		\
		this_cpu_add((mdev)->stats->stats.bytes_field, (len));	\
	} while (0)

#define MPLS_INC_STATS(mdev, field)			\
	this_cpu_inc((mdev)->stats->stats.field)

#endif

struct sk_buff;

#define LABEL_NOT_SPECIFIED (1 << 20)

/* This maximum ha length copied from the definition of struct neighbour */
#define VIA_ALEN_ALIGN sizeof(unsigned long)
#define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, VIA_ALEN_ALIGN))

enum mpls_payload_type {
	MPT_UNSPEC, /* IPv4 or IPv6 */
	MPT_IPV4 = 4,
	MPT_IPV6 = 6,

	/* Other types not implemented:
	 *  - Pseudo-wire with or without control word (RFC4385)
	 *  - GAL (RFC5586)
	 */
};

struct mpls_nh { /* next hop label forwarding entry */
	struct net_device __rcu *nh_dev;

	/* nh_flags is accessed under RCU in the packet path; it is
	 * modified handling netdev events with rtnl lock held
	 */
	unsigned int		nh_flags;
	u8			nh_labels;
	u8			nh_via_alen;
	u8			nh_via_table;
	u8			nh_reserved1;

	u32			nh_label[0];
};

/* offset of via from beginning of mpls_nh */
#define MPLS_NH_VIA_OFF(num_labels) \
		ALIGN(sizeof(struct mpls_nh) + (num_labels) * sizeof(u32), \
		      VIA_ALEN_ALIGN)

/* all nexthops within a route have the same size based on the
 * max number of labels and max via length across all nexthops
 */
#define MPLS_NH_SIZE(num_labels, max_via_alen)		\
		(MPLS_NH_VIA_OFF((num_labels)) +	\
		ALIGN((max_via_alen), VIA_ALEN_ALIGN))

enum mpls_ttl_propagation {
	MPLS_TTL_PROP_DEFAULT,
	MPLS_TTL_PROP_ENABLED,
	MPLS_TTL_PROP_DISABLED,
};

/* The route, nexthops and vias are stored together in the same memory
 * block:
 *
 * +----------------------+
 * | mpls_route           |
 * +----------------------+
 * | mpls_nh 0            |
 * +----------------------+
 * | alignment padding    |   4 bytes for odd number of labels
 * +----------------------+
 * | via[rt_max_alen] 0   |
 * +----------------------+
 * | alignment padding    |   via's aligned on sizeof(unsigned long)
 * +----------------------+
 * | ...                  |
 * +----------------------+
 * | mpls_nh n-1          |
 * +----------------------+
 * | via[rt_max_alen] n-1 |
 * +----------------------+
 */
struct mpls_route { /* next hop label forwarding entry */
	struct rcu_head		rt_rcu;
	u8			rt_protocol;
	u8			rt_payload_type;
	u8			rt_max_alen;
	u8			rt_ttl_propagate;
	u8			rt_nhn;
	/* rt_nhn_alive is accessed under RCU in the packet path; it
	 * is modified handling netdev events with rtnl lock held
	 */
	u8			rt_nhn_alive;
	u8			rt_nh_size;
	u8			rt_via_offset;
	u8			rt_reserved1;
	struct mpls_nh		rt_nh[0];
};

#define for_nexthops(rt) {						\
	int nhsel; struct mpls_nh *nh;  u8 *__nh;			\
	for (nhsel = 0, nh = (rt)->rt_nh, __nh = (u8 *)((rt)->rt_nh);	\
	     nhsel < (rt)->rt_nhn;					\
	     __nh += rt->rt_nh_size, nh = (struct mpls_nh *)__nh, nhsel++)

#define change_nexthops(rt) {						\
	int nhsel; struct mpls_nh *nh; u8 *__nh;			\
	for (nhsel = 0, nh = (struct mpls_nh *)((rt)->rt_nh),		\
			__nh = (u8 *)((rt)->rt_nh);			\
	     nhsel < (rt)->rt_nhn;					\
	     __nh += rt->rt_nh_size, nh = (struct mpls_nh *)__nh, nhsel++)

#define endfor_nexthops(rt) }

static inline struct mpls_shim_hdr mpls_entry_encode(u32 label, unsigned ttl, unsigned tc, bool bos)
{
	struct mpls_shim_hdr result;
	result.label_stack_entry =
		cpu_to_be32((label << MPLS_LS_LABEL_SHIFT) |
			    (tc << MPLS_LS_TC_SHIFT) |
			    (bos ? (1 << MPLS_LS_S_SHIFT) : 0) |
			    (ttl << MPLS_LS_TTL_SHIFT));
	return result;
}

static inline struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *hdr)
{
	struct mpls_entry_decoded result;
	unsigned entry = be32_to_cpu(hdr->label_stack_entry);

	result.label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
	result.ttl = (entry & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
	result.tc =  (entry & MPLS_LS_TC_MASK) >> MPLS_LS_TC_SHIFT;
	result.bos = (entry & MPLS_LS_S_MASK) >> MPLS_LS_S_SHIFT;

	return result;
}

static inline struct mpls_dev *mpls_dev_get(const struct net_device *dev)
{
	return rcu_dereference_rtnl(dev->mpls_ptr);
}

int nla_put_labels(struct sk_buff *skb, int attrtype,  u8 labels,
		   const u32 label[]);
int nla_get_labels(const struct nlattr *nla, u8 max_labels, u8 *labels,
		   u32 label[], struct netlink_ext_ack *extack);
bool mpls_output_possible(const struct net_device *dev);
unsigned int mpls_dev_mtu(const struct net_device *dev);
bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu);
void mpls_stats_inc_outucastpkts(struct net_device *dev,
				 const struct sk_buff *skb);

#endif /* MPLS_INTERNAL_H */