include/net/nexthop.h

File Facts

System

Linux kernel

Corpus path

include/net/nexthop.h

Extension

.h

Size

13056 bytes

Lines

589

Domain

Networking Core

Bucket

Sockets, Protocols, Packet Path, And Network Policy

Inferred role

Networking Core: implementation source

Status

source implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

• Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/netdevice.h
• linux/notifier.h
• linux/route.h
• linux/types.h
• net/ip_fib.h
• net/ip6_fib.h
• net/netlink.h

Detected Declarations

• struct nexthop
• struct nh_config
• struct nh_info
• struct nh_res_bucket
• struct nh_res_table
• struct nh_grp_entry_stats
• struct nh_grp_entry
• struct nh_group
• struct nexthop
• struct nh_notifier_single_info
• struct nh_notifier_grp_entry_info
• struct nh_notifier_grp_info
• struct nh_notifier_res_bucket_info
• struct nh_notifier_res_table_info
• struct nh_notifier_grp_hw_stats_entry_info
• struct nh_notifier_grp_hw_stats_info
• struct nh_notifier_info
• enum nexthop_event_type
• enum nh_notifier_info_type
• function nexthop_get
• function nexthop_put
• function nexthop_cmp
• function nexthop_is_fdb
• function nexthop_has_v4
• function nexthop_is_multipath
• function nexthop_num_path
• function nexthop_mpath_fill_node
• function nexthop_is_blackhole
• function nexthop_path_fib_result
• function nexthop_uses_dev
• function fib_info_num_path
• function nexthop_path_fib6_result
• function nexthop_get_family

Annotated Snippet

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;

	bool		nh_hw_stats;

	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[] __counted_by(num_nh_buckets);
};

struct nh_grp_entry_stats {
	u64_stats_t packets;
	struct u64_stats_sync syncp;
};

struct nh_grp_entry {
	struct nexthop	*nh;
	struct nh_grp_entry_stats __percpu	*stats;
	u16		weight;

	union {
		struct {
			atomic_t	upper_bound;
		} hthr;

Annotation

• Immediate include surface: `linux/netdevice.h`, `linux/notifier.h`, `linux/route.h`, `linux/types.h`, `net/ip_fib.h`, `net/ip6_fib.h`, `net/netlink.h`.
• Detected declarations: `struct nexthop`, `struct nh_config`, `struct nh_info`, `struct nh_res_bucket`, `struct nh_res_table`, `struct nh_grp_entry_stats`, `struct nh_grp_entry`, `struct nh_group`, `struct nexthop`, `struct nh_notifier_single_info`.
• Atlas domain: Networking Core / Sockets, Protocols, Packet Path, And Network Policy.
• Implementation status: source implementation candidate.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.