include/net/nexthop.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Generic nexthop implementation
  *
  * Copyright (c) 2017-19 Cumulus Networks
  * Copyright (c) 2017-19 David Ahern <dsa@cumulusnetworks.com>
  */

 #ifndef __LINUX_NEXTHOP_H
 #define __LINUX_NEXTHOP_H

 #include <linux/netdevice.h>
 #include <linux/notifier.h>
 #include <linux/route.h>
 #include <linux/types.h>
 #include <net/ip_fib.h>
 #include <net/ip6_fib.h>
 #include <net/netlink.h>

 #define NEXTHOP_VALID_USER_FLAGS RTNH_F_ONLINK

 struct nexthop;

 struct nh_config {
 	u32		nh_id;

 	u8		nh_family;
 	u8		nh_protocol;
 	u8		nh_blackhole;
 	u8		nh_fdb;
 	u32		nh_flags;

 	int		nh_ifindex;
 	struct net_device *dev;

 	union {
 		__be32		ipv4;
 		struct in6_addr	ipv6;
 	} gw;

 	struct nlattr	*nh_grp;
 	u16		nh_grp_type;
 	u16		nh_grp_res_num_buckets;
 	unsigned long	nh_grp_res_idle_timer;
 	unsigned long	nh_grp_res_unbalanced_timer;
 	bool		nh_grp_res_has_num_buckets;
 	bool		nh_grp_res_has_idle_timer;
 	bool		nh_grp_res_has_unbalanced_timer;

 	struct nlattr	*nh_encap;
 	u16		nh_encap_type;

 	u32		nlflags;
 	struct nl_info	nlinfo;
 };

 struct nh_info {
 	struct hlist_node	dev_hash;    /* entry on netns devhash */
 	struct nexthop		*nh_parent;

 	u8			family;
 	bool			reject_nh;
 	bool			fdb_nh;

 	union {
 		struct fib_nh_common	fib_nhc;
 		struct fib_nh		fib_nh;
 		struct fib6_nh		fib6_nh;
 	};
 };

 struct nh_res_bucket {
 	struct nh_grp_entry __rcu *nh_entry;
 	atomic_long_t		used_time;
 	unsigned long		migrated_time;
 	bool			occupied;
 	u8			nh_flags;
 };

 struct nh_res_table {
 	struct net		*net;
 	u32			nhg_id;
 	struct delayed_work	upkeep_dw;

 	/* List of NHGEs that have too few buckets ("uw" for underweight).
 	 * Reclaimed buckets will be given to entries in this list.
 	 */
 	struct list_head	uw_nh_entries;
 	unsigned long		unbalanced_since;

 	u32			idle_timer;
 	u32			unbalanced_timer;

 	u16			num_nh_buckets;
 	struct nh_res_bucket	nh_buckets[];
 };

 struct nh_grp_entry {
 	struct nexthop	*nh;
 	u8		weight;

 	union {
 		struct {
 			atomic_t	upper_bound;
 		} hthr;
 		struct {
 			/* Member on uw_nh_entries. */
 			struct list_head	uw_nh_entry;

 			u16			count_buckets;
 			u16			wants_buckets;
 		} res;
 	};

 	struct list_head nh_list;
 	struct nexthop	*nh_parent;  /* nexthop of group with this entry */
 };

 struct nh_group {
 	struct nh_group		*spare; /* spare group for removals */
 	u16			num_nh;
 	bool			is_multipath;
 	bool			hash_threshold;
 	bool			resilient;
 	bool			fdb_nh;
 	bool			has_v4;

 	struct nh_res_table __rcu *res_table;
 	struct nh_grp_entry	nh_entries[];
 };

 struct nexthop {
 	struct rb_node		rb_node;    /* entry on netns rbtree */
 	struct list_head	fi_list;    /* v4 entries using nh */
 	struct list_head	f6i_list;   /* v6 entries using nh */
 	struct list_head        fdb_list;   /* fdb entries using this nh */
 	struct list_head	grp_list;   /* nh group entries using this nh */
 	struct net		*net;

 	u32			id;

 	u8			protocol;   /* app managing this nh */
 	u8			nh_flags;
 	bool			is_group;

 	refcount_t		refcnt;
 	struct rcu_head		rcu;

 	union {
 		struct nh_info	__rcu *nh_info;
 		struct nh_group __rcu *nh_grp;
 	};
 };

 enum nexthop_event_type {
 	NEXTHOP_EVENT_DEL,
 	NEXTHOP_EVENT_REPLACE,
 	NEXTHOP_EVENT_RES_TABLE_PRE_REPLACE,
 	NEXTHOP_EVENT_BUCKET_REPLACE,
 };

 enum nh_notifier_info_type {
 	NH_NOTIFIER_INFO_TYPE_SINGLE,
 	NH_NOTIFIER_INFO_TYPE_GRP,
 	NH_NOTIFIER_INFO_TYPE_RES_TABLE,
 	NH_NOTIFIER_INFO_TYPE_RES_BUCKET,
 };

 struct nh_notifier_single_info {
 	struct net_device *dev;
 	u8 gw_family;
 	union {
 		__be32 ipv4;
 		struct in6_addr ipv6;
 	};
 	u8 is_reject:1,
 	   is_fdb:1,
 	   has_encap:1;
 };

 struct nh_notifier_grp_entry_info {
 	u8 weight;
 	u32 id;
 	struct nh_notifier_single_info nh;
 };

 struct nh_notifier_grp_info {
 	u16 num_nh;
 	bool is_fdb;
 	struct nh_notifier_grp_entry_info nh_entries[];
 };

 struct nh_notifier_res_bucket_info {
 	u16 bucket_index;
 	unsigned int idle_timer_ms;
 	bool force;
 	struct nh_notifier_single_info old_nh;
 	struct nh_notifier_single_info new_nh;
 };

 struct nh_notifier_res_table_info {
 	u16 num_nh_buckets;
 	struct nh_notifier_single_info nhs[];
 };

 struct nh_notifier_info {
 	struct net *net;
 	struct netlink_ext_ack *extack;
 	u32 id;
 	enum nh_notifier_info_type type;
 	union {
 		struct nh_notifier_single_info *nh;
 		struct nh_notifier_grp_info *nh_grp;
 		struct nh_notifier_res_table_info *nh_res_table;
 		struct nh_notifier_res_bucket_info *nh_res_bucket;
 	};
 };

 int register_nexthop_notifier(struct net *net, struct notifier_block *nb,
 			      struct netlink_ext_ack *extack);
 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
 void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap);
 void nexthop_bucket_set_hw_flags(struct net *net, u32 id, u16 bucket_index,
 				 bool offload, bool trap);
 void nexthop_res_grp_activity_update(struct net *net, u32 id, u16 num_buckets,
 				     unsigned long *activity);

 /* caller is holding rcu or rtnl; no reference taken to nexthop */
 struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
 void nexthop_free_rcu(struct rcu_head *head);

 static inline bool nexthop_get(struct nexthop *nh)
 {
 	return refcount_inc_not_zero(&nh->refcnt);
 }

 static inline void nexthop_put(struct nexthop *nh)
 {
 	if (refcount_dec_and_test(&nh->refcnt))
 		call_rcu(&nh->rcu, nexthop_free_rcu);
 }

 static inline bool nexthop_cmp(const struct nexthop *nh1,
 			       const struct nexthop *nh2)
 {
 	return nh1 == nh2;
 }

 static inline bool nexthop_is_fdb(const struct nexthop *nh)
 {
 	if (nh->is_group) {
 		const struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		return nh_grp->fdb_nh;
 	} else {
 		const struct nh_info *nhi;

 		nhi = rcu_dereference_rtnl(nh->nh_info);
 		return nhi->fdb_nh;
 	}
 }

 static inline bool nexthop_has_v4(const struct nexthop *nh)
 {
 	if (nh->is_group) {
 		struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		return nh_grp->has_v4;
 	}
 	return false;
 }

 static inline bool nexthop_is_multipath(const struct nexthop *nh)
 {
 	if (nh->is_group) {
 		struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		return nh_grp->is_multipath;
 	}
 	return false;
 }

 struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);

 static inline unsigned int nexthop_num_path(const struct nexthop *nh)
 {
 	unsigned int rc = 1;

 	if (nh->is_group) {
 		struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		if (nh_grp->is_multipath)
 			rc = nh_grp->num_nh;
 	}

 	return rc;
 }

 static inline
 struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
 {
 	/* for_nexthops macros in fib_semantics.c grabs a pointer to
 	 * the nexthop before checking nhsel
 	 */
 	if (nhsel >= nhg->num_nh)
 		return NULL;

 	return nhg->nh_entries[nhsel].nh;
 }

 static inline
 int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 			    u8 rt_family)
 {
 	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
 	int i;

 	for (i = 0; i < nhg->num_nh; i++) {
 		struct nexthop *nhe = nhg->nh_entries[i].nh;
 		struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
 		struct fib_nh_common *nhc = &nhi->fib_nhc;
 		int weight = nhg->nh_entries[i].weight;

 		if (fib_add_nexthop(skb, nhc, weight, rt_family, 0) < 0)
 			return -EMSGSIZE;
 	}

 	return 0;
 }

 /* called with rcu lock */
 static inline bool nexthop_is_blackhole(const struct nexthop *nh)
 {
 	const struct nh_info *nhi;

 	if (nh->is_group) {
 		struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		if (nh_grp->num_nh > 1)
 			return false;

 		nh = nh_grp->nh_entries[0].nh;
 	}

 	nhi = rcu_dereference_rtnl(nh->nh_info);
 	return nhi->reject_nh;
 }

 static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
 {
 	struct nh_info *nhi;
 	struct nexthop *nh;

 	nh = nexthop_select_path(res->fi->nh, hash);
 	nhi = rcu_dereference(nh->nh_info);
 	res->nhc = &nhi->fib_nhc;
 }

 /* called with rcu read lock or rtnl held */
 static inline
 struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
 {
 	struct nh_info *nhi;

 	BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
 	BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);

 	if (nh->is_group) {
 		struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		if (nh_grp->is_multipath) {
 			nh = nexthop_mpath_select(nh_grp, nhsel);
 			if (!nh)
 				return NULL;
 		}
 	}

 	nhi = rcu_dereference_rtnl(nh->nh_info);
 	return &nhi->fib_nhc;
 }

 /* called from fib_table_lookup with rcu_lock */
 static inline
 struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
 					     int fib_flags,
 					     const struct flowi4 *flp,
 					     int *nhsel)
 {
 	struct nh_info *nhi;

 	if (nh->is_group) {
 		struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 		int i;

 		for (i = 0; i < nhg->num_nh; i++) {
 			struct nexthop *nhe = nhg->nh_entries[i].nh;

 			nhi = rcu_dereference(nhe->nh_info);
 			if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 				*nhsel = i;
 				return &nhi->fib_nhc;
 			}
 		}
 	} else {
 		nhi = rcu_dereference(nh->nh_info);
 		if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
 			*nhsel = 0;
 			return &nhi->fib_nhc;
 		}
 	}

 	return NULL;
 }

 static inline bool nexthop_uses_dev(const struct nexthop *nh,
 				    const struct net_device *dev)
 {
 	struct nh_info *nhi;

 	if (nh->is_group) {
 		struct nh_group *nhg = rcu_dereference(nh->nh_grp);
 		int i;

 		for (i = 0; i < nhg->num_nh; i++) {
 			struct nexthop *nhe = nhg->nh_entries[i].nh;

 			nhi = rcu_dereference(nhe->nh_info);
 			if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 				return true;
 		}
 	} else {
 		nhi = rcu_dereference(nh->nh_info);
 		if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
 			return true;
 	}

 	return false;
 }

 static inline unsigned int fib_info_num_path(const struct fib_info *fi)
 {
 	if (unlikely(fi->nh))
 		return nexthop_num_path(fi->nh);

 	return fi->fib_nhs;
 }

 int fib_check_nexthop(struct nexthop *nh, u8 scope,
 		      struct netlink_ext_ack *extack);

 static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
 {
 	if (unlikely(fi->nh))
 		return nexthop_fib_nhc(fi->nh, nhsel);

 	return &fi->fib_nh[nhsel].nh_common;
 }

 /* only used when fib_nh is built into fib_info */
 static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
 {
 	WARN_ON(fi->nh);

 	return &fi->fib_nh[nhsel];
 }

 /*
  * IPv6 variants
  */
 int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
 		       struct netlink_ext_ack *extack);

 /* Caller should either hold rcu_read_lock(), or RTNL. */
 static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
 {
 	struct nh_info *nhi;

 	if (nh->is_group) {
 		struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		nh = nexthop_mpath_select(nh_grp, 0);
 		if (!nh)
 			return NULL;
 	}

 	nhi = rcu_dereference_rtnl(nh->nh_info);
 	if (nhi->family == AF_INET6)
 		return &nhi->fib6_nh;

 	return NULL;
 }

 /* Variant of nexthop_fib6_nh().
  * Caller should either hold rcu_read_lock(), or RTNL.
  */
 static inline struct fib6_nh *nexthop_fib6_nh_bh(struct nexthop *nh)
 {
 	struct nh_info *nhi;

 	if (nh->is_group) {
 		struct nh_group *nh_grp;

 		nh_grp = rcu_dereference_rtnl(nh->nh_grp);
 		nh = nexthop_mpath_select(nh_grp, 0);
 		if (!nh)
 			return NULL;
 	}

 	nhi = rcu_dereference_rtnl(nh->nh_info);
 	if (nhi->family == AF_INET6)
 		return &nhi->fib6_nh;

 	return NULL;
 }

 static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
 {
 	struct fib6_nh *fib6_nh;

 	fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
 	return fib6_nh->fib_nh_dev;
 }

 static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
 {
 	struct nexthop *nh = res->f6i->nh;
 	struct nh_info *nhi;

 	nh = nexthop_select_path(nh, hash);

 	nhi = rcu_dereference_rtnl(nh->nh_info);
 	if (nhi->reject_nh) {
 		res->fib6_type = RTN_BLACKHOLE;
 		res->fib6_flags |= RTF_REJECT;
 		res->nh = nexthop_fib6_nh(nh);
 	} else {
 		res->nh = &nhi->fib6_nh;
 	}
 }

 int nexthop_for_each_fib6_nh(struct nexthop *nh,
 			     int (*cb)(struct fib6_nh *nh, void *arg),
 			     void *arg);

 static inline int nexthop_get_family(struct nexthop *nh)
 {
 	struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);

 	return nhi->family;
 }

 static inline
 struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
 {
 	struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);

 	return &nhi->fib_nhc;
 }

 static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop *nh,
 							    int hash)
 {
 	struct nh_info *nhi;
 	struct nexthop *nhp;

 	nhp = nexthop_select_path(nh, hash);
 	if (unlikely(!nhp))
 		return NULL;
 	nhi = rcu_dereference(nhp->nh_info);
 	return &nhi->fib_nhc;
 }
 #endif
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* Generic nexthop implementation
	*
	* Copyright (c) 2017-19 Cumulus Networks
	* Copyright (c) 2017-19 David Ahern <dsa@cumulusnetworks.com>
	*/

	#ifndef __LINUX_NEXTHOP_H
	#define __LINUX_NEXTHOP_H

	#include <linux/netdevice.h>
	#include <linux/notifier.h>
	#include <linux/route.h>
	#include <linux/types.h>
	#include <net/ip_fib.h>
	#include <net/ip6_fib.h>
	#include <net/netlink.h>

	#define NEXTHOP_VALID_USER_FLAGS RTNH_F_ONLINK

	struct nexthop;

	struct nh_config {
	u32 nh_id;

	u8 nh_family;
	u8 nh_protocol;
	u8 nh_blackhole;
	u8 nh_fdb;
	u32 nh_flags;

	int nh_ifindex;
	struct net_device *dev;

	union {
	__be32 ipv4;
	struct in6_addr ipv6;
	} gw;

	struct nlattr *nh_grp;
	u16 nh_grp_type;
	u16 nh_grp_res_num_buckets;
	unsigned long nh_grp_res_idle_timer;
	unsigned long nh_grp_res_unbalanced_timer;
	bool nh_grp_res_has_num_buckets;
	bool nh_grp_res_has_idle_timer;
	bool nh_grp_res_has_unbalanced_timer;

	struct nlattr *nh_encap;
	u16 nh_encap_type;

	u32 nlflags;
	struct nl_info nlinfo;
	};

	struct nh_info {
	struct hlist_node dev_hash; /* entry on netns devhash */
	struct nexthop *nh_parent;

	u8 family;
	bool reject_nh;
	bool fdb_nh;

	union {
	struct fib_nh_common fib_nhc;
	struct fib_nh fib_nh;
	struct fib6_nh fib6_nh;
	};
	};

	struct nh_res_bucket {
	struct nh_grp_entry __rcu *nh_entry;
	atomic_long_t used_time;
	unsigned long migrated_time;
	bool occupied;
	u8 nh_flags;
	};

	struct nh_res_table {
	struct net *net;
	u32 nhg_id;
	struct delayed_work upkeep_dw;

	/* List of NHGEs that have too few buckets ("uw" for underweight).
	* Reclaimed buckets will be given to entries in this list.
	*/
	struct list_head uw_nh_entries;
	unsigned long unbalanced_since;

	u32 idle_timer;
	u32 unbalanced_timer;

	u16 num_nh_buckets;
	struct nh_res_bucket nh_buckets[];
	};

	struct nh_grp_entry {
	struct nexthop *nh;
	u8 weight;

	union {
	struct {
	atomic_t upper_bound;
	} hthr;
	struct {
	/* Member on uw_nh_entries. */
	struct list_head uw_nh_entry;

	u16 count_buckets;
	u16 wants_buckets;
	} res;
	};

	struct list_head nh_list;
	struct nexthop nh_parent; / nexthop of group with this entry */
	};

	struct nh_group {
	struct nh_group spare; / spare group for removals */
	u16 num_nh;
	bool is_multipath;
	bool hash_threshold;
	bool resilient;
	bool fdb_nh;
	bool has_v4;

	struct nh_res_table __rcu *res_table;
	struct nh_grp_entry nh_entries[];
	};

	struct nexthop {
	struct rb_node rb_node; /* entry on netns rbtree */
	struct list_head fi_list; /* v4 entries using nh */
	struct list_head f6i_list; /* v6 entries using nh */
	struct list_head fdb_list; /* fdb entries using this nh */
	struct list_head grp_list; /* nh group entries using this nh */
	struct net *net;

	u32 id;

	u8 protocol; /* app managing this nh */
	u8 nh_flags;
	bool is_group;

	refcount_t refcnt;
	struct rcu_head rcu;

	union {
	struct nh_info __rcu *nh_info;
	struct nh_group __rcu *nh_grp;
	};
	};

	enum nexthop_event_type {
	NEXTHOP_EVENT_DEL,
	NEXTHOP_EVENT_REPLACE,
	NEXTHOP_EVENT_RES_TABLE_PRE_REPLACE,
	NEXTHOP_EVENT_BUCKET_REPLACE,
	};

	enum nh_notifier_info_type {
	NH_NOTIFIER_INFO_TYPE_SINGLE,
	NH_NOTIFIER_INFO_TYPE_GRP,
	NH_NOTIFIER_INFO_TYPE_RES_TABLE,
	NH_NOTIFIER_INFO_TYPE_RES_BUCKET,
	};

	struct nh_notifier_single_info {
	struct net_device *dev;
	u8 gw_family;
	union {
	__be32 ipv4;
	struct in6_addr ipv6;
	};
	u8 is_reject:1,
	is_fdb:1,
	has_encap:1;
	};

	struct nh_notifier_grp_entry_info {
	u8 weight;
	u32 id;
	struct nh_notifier_single_info nh;
	};

	struct nh_notifier_grp_info {
	u16 num_nh;
	bool is_fdb;
	struct nh_notifier_grp_entry_info nh_entries[];
	};

	struct nh_notifier_res_bucket_info {
	u16 bucket_index;
	unsigned int idle_timer_ms;
	bool force;
	struct nh_notifier_single_info old_nh;
	struct nh_notifier_single_info new_nh;
	};

	struct nh_notifier_res_table_info {
	u16 num_nh_buckets;
	struct nh_notifier_single_info nhs[];
	};

	struct nh_notifier_info {
	struct net *net;
	struct netlink_ext_ack *extack;
	u32 id;
	enum nh_notifier_info_type type;
	union {
	struct nh_notifier_single_info *nh;
	struct nh_notifier_grp_info *nh_grp;
	struct nh_notifier_res_table_info *nh_res_table;
	struct nh_notifier_res_bucket_info *nh_res_bucket;
	};
	};

	int register_nexthop_notifier(struct net net, struct notifier_block nb,
	struct netlink_ext_ack *extack);
	int unregister_nexthop_notifier(struct net net, struct notifier_block nb);
	void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap);
	void nexthop_bucket_set_hw_flags(struct net *net, u32 id, u16 bucket_index,
	bool offload, bool trap);
	void nexthop_res_grp_activity_update(struct net *net, u32 id, u16 num_buckets,
	unsigned long *activity);

	/* caller is holding rcu or rtnl; no reference taken to nexthop */
	struct nexthop nexthop_find_by_id(struct net net, u32 id);
	void nexthop_free_rcu(struct rcu_head *head);

	static inline bool nexthop_get(struct nexthop *nh)
	{
	return refcount_inc_not_zero(&nh->refcnt);
	}

	static inline void nexthop_put(struct nexthop *nh)
	{
	if (refcount_dec_and_test(&nh->refcnt))
	call_rcu(&nh->rcu, nexthop_free_rcu);
	}

	static inline bool nexthop_cmp(const struct nexthop *nh1,
	const struct nexthop *nh2)
	{
	return nh1 == nh2;
	}

	static inline bool nexthop_is_fdb(const struct nexthop *nh)
	{
	if (nh->is_group) {
	const struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	return nh_grp->fdb_nh;
	} else {
	const struct nh_info *nhi;

	nhi = rcu_dereference_rtnl(nh->nh_info);
	return nhi->fdb_nh;
	}
	}

	static inline bool nexthop_has_v4(const struct nexthop *nh)
	{
	if (nh->is_group) {
	struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	return nh_grp->has_v4;
	}
	return false;
	}

	static inline bool nexthop_is_multipath(const struct nexthop *nh)
	{
	if (nh->is_group) {
	struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	return nh_grp->is_multipath;
	}
	return false;
	}

	struct nexthop nexthop_select_path(struct nexthop nh, int hash);

	static inline unsigned int nexthop_num_path(const struct nexthop *nh)
	{
	unsigned int rc = 1;

	if (nh->is_group) {
	struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	if (nh_grp->is_multipath)
	rc = nh_grp->num_nh;
	}

	return rc;
	}

	static inline
	struct nexthop nexthop_mpath_select(const struct nh_group nhg, int nhsel)
	{
	/* for_nexthops macros in fib_semantics.c grabs a pointer to
	* the nexthop before checking nhsel
	*/
	if (nhsel >= nhg->num_nh)
	return NULL;

	return nhg->nh_entries[nhsel].nh;
	}

	static inline
	int nexthop_mpath_fill_node(struct sk_buff skb, struct nexthop nh,
	u8 rt_family)
	{
	struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
	int i;

	for (i = 0; i < nhg->num_nh; i++) {
	struct nexthop *nhe = nhg->nh_entries[i].nh;
	struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
	struct fib_nh_common *nhc = &nhi->fib_nhc;
	int weight = nhg->nh_entries[i].weight;

	if (fib_add_nexthop(skb, nhc, weight, rt_family, 0) < 0)
	return -EMSGSIZE;
	}

	return 0;
	}

	/* called with rcu lock */
	static inline bool nexthop_is_blackhole(const struct nexthop *nh)
	{
	const struct nh_info *nhi;

	if (nh->is_group) {
	struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	if (nh_grp->num_nh > 1)
	return false;

	nh = nh_grp->nh_entries[0].nh;
	}

	nhi = rcu_dereference_rtnl(nh->nh_info);
	return nhi->reject_nh;
	}

	static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
	{
	struct nh_info *nhi;
	struct nexthop *nh;

	nh = nexthop_select_path(res->fi->nh, hash);
	nhi = rcu_dereference(nh->nh_info);
	res->nhc = &nhi->fib_nhc;
	}

	/* called with rcu read lock or rtnl held */
	static inline
	struct fib_nh_common nexthop_fib_nhc(struct nexthop nh, int nhsel)
	{
	struct nh_info *nhi;

	BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
	BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);

	if (nh->is_group) {
	struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	if (nh_grp->is_multipath) {
	nh = nexthop_mpath_select(nh_grp, nhsel);
	if (!nh)
	return NULL;
	}
	}

	nhi = rcu_dereference_rtnl(nh->nh_info);
	return &nhi->fib_nhc;
	}

	/* called from fib_table_lookup with rcu_lock */
	static inline
	struct fib_nh_common nexthop_get_nhc_lookup(const struct nexthop nh,
	int fib_flags,
	const struct flowi4 *flp,
	int *nhsel)
	{
	struct nh_info *nhi;

	if (nh->is_group) {
	struct nh_group *nhg = rcu_dereference(nh->nh_grp);
	int i;

	for (i = 0; i < nhg->num_nh; i++) {
	struct nexthop *nhe = nhg->nh_entries[i].nh;

	nhi = rcu_dereference(nhe->nh_info);
	if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
	*nhsel = i;
	return &nhi->fib_nhc;
	}
	}
	} else {
	nhi = rcu_dereference(nh->nh_info);
	if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
	*nhsel = 0;
	return &nhi->fib_nhc;
	}
	}

	return NULL;
	}

	static inline bool nexthop_uses_dev(const struct nexthop *nh,
	const struct net_device *dev)
	{
	struct nh_info *nhi;

	if (nh->is_group) {
	struct nh_group *nhg = rcu_dereference(nh->nh_grp);
	int i;

	for (i = 0; i < nhg->num_nh; i++) {
	struct nexthop *nhe = nhg->nh_entries[i].nh;

	nhi = rcu_dereference(nhe->nh_info);
	if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
	return true;
	}
	} else {
	nhi = rcu_dereference(nh->nh_info);
	if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
	return true;
	}

	return false;
	}

	static inline unsigned int fib_info_num_path(const struct fib_info *fi)
	{
	if (unlikely(fi->nh))
	return nexthop_num_path(fi->nh);

	return fi->fib_nhs;
	}

	int fib_check_nexthop(struct nexthop *nh, u8 scope,
	struct netlink_ext_ack *extack);

	static inline struct fib_nh_common fib_info_nhc(struct fib_info fi, int nhsel)
	{
	if (unlikely(fi->nh))
	return nexthop_fib_nhc(fi->nh, nhsel);

	return &fi->fib_nh[nhsel].nh_common;
	}

	/* only used when fib_nh is built into fib_info */
	static inline struct fib_nh fib_info_nh(struct fib_info fi, int nhsel)
	{
	WARN_ON(fi->nh);

	return &fi->fib_nh[nhsel];
	}

	/*
	* IPv6 variants
	*/
	int fib6_check_nexthop(struct nexthop nh, struct fib6_config cfg,
	struct netlink_ext_ack *extack);

	/* Caller should either hold rcu_read_lock(), or RTNL. */
	static inline struct fib6_nh nexthop_fib6_nh(struct nexthop nh)
	{
	struct nh_info *nhi;

	if (nh->is_group) {
	struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	nh = nexthop_mpath_select(nh_grp, 0);
	if (!nh)
	return NULL;
	}

	nhi = rcu_dereference_rtnl(nh->nh_info);
	if (nhi->family == AF_INET6)
	return &nhi->fib6_nh;

	return NULL;
	}

	/* Variant of nexthop_fib6_nh().
	* Caller should either hold rcu_read_lock(), or RTNL.
	*/
	static inline struct fib6_nh nexthop_fib6_nh_bh(struct nexthop nh)
	{
	struct nh_info *nhi;

	if (nh->is_group) {
	struct nh_group *nh_grp;

	nh_grp = rcu_dereference_rtnl(nh->nh_grp);
	nh = nexthop_mpath_select(nh_grp, 0);
	if (!nh)
	return NULL;
	}

	nhi = rcu_dereference_rtnl(nh->nh_info);
	if (nhi->family == AF_INET6)
	return &nhi->fib6_nh;

	return NULL;
	}

	static inline struct net_device fib6_info_nh_dev(struct fib6_info f6i)
	{
	struct fib6_nh *fib6_nh;

	fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
	return fib6_nh->fib_nh_dev;
	}

	static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
	{
	struct nexthop *nh = res->f6i->nh;
	struct nh_info *nhi;

	nh = nexthop_select_path(nh, hash);

	nhi = rcu_dereference_rtnl(nh->nh_info);
	if (nhi->reject_nh) {
	res->fib6_type = RTN_BLACKHOLE;
	res->fib6_flags \|= RTF_REJECT;
	res->nh = nexthop_fib6_nh(nh);
	} else {
	res->nh = &nhi->fib6_nh;
	}
	}

	int nexthop_for_each_fib6_nh(struct nexthop *nh,
	int (cb)(struct fib6_nh nh, void *arg),
	void *arg);

	static inline int nexthop_get_family(struct nexthop *nh)
	{
	struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);

	return nhi->family;
	}

	static inline
	struct fib_nh_common nexthop_fdb_nhc(struct nexthop nh)
	{
	struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);

	return &nhi->fib_nhc;
	}

	static inline struct fib_nh_common nexthop_path_fdb_result(struct nexthop nh,
	int hash)
	{
	struct nh_info *nhi;
	struct nexthop *nhp;

	nhp = nexthop_select_path(nh, hash);
	if (unlikely(!nhp))
	return NULL;
	nhi = rcu_dereference(nhp->nh_info);
	return &nhi->fib_nhc;
	}
	#endif