net/l2tp/l2tp_debugfs.c

File Facts

System

Linux kernel

Corpus path

net/l2tp/l2tp_debugfs.c

Extension

.c

Size

9155 bytes

Lines

348

Domain

Networking Core

Bucket

Sockets, Protocols, Packet Path, And Network Policy

Inferred role

Networking Core: operation-table or driver-model contract

Status

pattern 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.
• Defines an operation table; this is where Linux turns generic core objects into subsystem-specific behavior.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/module.h
• linux/skbuff.h
• linux/socket.h
• linux/hash.h
• linux/l2tp.h
• linux/in.h
• linux/etherdevice.h
• linux/spinlock.h
• linux/debugfs.h
• net/sock.h
• net/ip.h
• net/icmp.h
• net/udp.h
• net/inet_common.h
• net/inet_hashtables.h
• net/tcp_states.h
• net/protocol.h
• net/xfrm.h
• net/net_namespace.h
• net/netns/generic.h
• l2tp_core.h

Detected Declarations

• struct l2tp_dfs_seq_data
• function l2tp_dfs_next_tunnel
• function l2tp_dfs_next_session
• function l2tp_dfs_seq_stop
• function l2tp_dfs_next_tunnel
• function l2tp_dfs_seq_tunnel_show
• function l2tp_dfs_seq_session_show
• function l2tp_dfs_seq_show
• function l2tp_dfs_seq_open
• function l2tp_dfs_seq_release
• function l2tp_debugfs_init
• function l2tp_debugfs_exit
• module init l2tp_debugfs_init

Annotated Snippet

static const struct file_operations l2tp_dfs_fops = {
	.owner		= THIS_MODULE,
	.open		= l2tp_dfs_seq_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= l2tp_dfs_seq_release,
};

static int __init l2tp_debugfs_init(void)
{
	rootdir = debugfs_create_dir("l2tp", NULL);

	debugfs_create_file("tunnels", 0600, rootdir, NULL, &l2tp_dfs_fops);

	pr_info("L2TP debugfs support\n");

	return 0;
}

static void __exit l2tp_debugfs_exit(void)
{
	debugfs_remove_recursive(rootdir);
}

module_init(l2tp_debugfs_init);
module_exit(l2tp_debugfs_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("L2TP debugfs driver");
MODULE_VERSION("1.0");

Annotation

• Immediate include surface: `linux/module.h`, `linux/skbuff.h`, `linux/socket.h`, `linux/hash.h`, `linux/l2tp.h`, `linux/in.h`, `linux/etherdevice.h`, `linux/spinlock.h`.
• Detected declarations: `struct l2tp_dfs_seq_data`, `function l2tp_dfs_next_tunnel`, `function l2tp_dfs_next_session`, `function l2tp_dfs_seq_stop`, `function l2tp_dfs_next_tunnel`, `function l2tp_dfs_seq_tunnel_show`, `function l2tp_dfs_seq_session_show`, `function l2tp_dfs_seq_show`, `function l2tp_dfs_seq_open`, `function l2tp_dfs_seq_release`.
• Atlas domain: Networking Core / Sockets, Protocols, Packet Path, And Network Policy.
• Implementation status: pattern 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.