net/802/psnap.c

File Facts

System

Linux kernel

Corpus path

net/802/psnap.c

Extension

.c

Size

3405 bytes

Lines

165

Domain

Networking Core

Bucket

Sockets, Protocols, Packet Path, And Network Policy

Inferred role

Networking Core: exported/initcall integration point

Status

integration 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.
• Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.
• 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/netdevice.h
• linux/skbuff.h
• linux/slab.h
• net/datalink.h
• net/llc.h
• net/psnap.h
• linux/mm.h
• linux/in.h
• linux/init.h
• linux/rculist.h

Detected Declarations

• function list_for_each_entry_rcu
• function snap_rcv
• function snap_request
• function snap_init
• function snap_exit
• function int
• function unregister_snap_client
• module init snap_init
• export register_snap_client
• export unregister_snap_client

Annotated Snippet

module_init(snap_init);

static void __exit snap_exit(void)
{
	llc_sap_put(snap_sap);
}

module_exit(snap_exit);


/*
 *	Register SNAP clients. We don't yet use this for IP.
 */
struct datalink_proto *register_snap_client(const unsigned char *desc,
					    int (*rcvfunc)(struct sk_buff *,
							   struct net_device *,
							   struct packet_type *,
							   struct net_device *))
{
	struct datalink_proto *proto = NULL;

	spin_lock_bh(&snap_lock);

	if (find_snap_client(desc))
		goto out;

	proto = kmalloc_obj(*proto, GFP_ATOMIC);
	if (proto) {
		memcpy(proto->type, desc, 5);
		proto->rcvfunc		= rcvfunc;
		proto->header_length	= 5 + 3; /* snap + 802.2 */
		proto->request		= snap_request;
		list_add_rcu(&proto->node, &snap_list);
	}
out:
	spin_unlock_bh(&snap_lock);

	return proto;
}

/*
 *	Unregister SNAP clients. Protocols no longer want to play with us ...
 */
void unregister_snap_client(struct datalink_proto *proto)
{
	spin_lock_bh(&snap_lock);
	list_del_rcu(&proto->node);
	spin_unlock_bh(&snap_lock);

	synchronize_net();

	kfree(proto);
}

MODULE_DESCRIPTION("SNAP data link layer. Derived from 802.2");
MODULE_LICENSE("GPL");

Annotation

• Immediate include surface: `linux/module.h`, `linux/netdevice.h`, `linux/skbuff.h`, `linux/slab.h`, `net/datalink.h`, `net/llc.h`, `net/psnap.h`, `linux/mm.h`.
• Detected declarations: `function list_for_each_entry_rcu`, `function snap_rcv`, `function snap_request`, `function snap_init`, `function snap_exit`, `function int`, `function unregister_snap_client`, `module init snap_init`, `export register_snap_client`, `export unregister_snap_client`.
• Atlas domain: Networking Core / Sockets, Protocols, Packet Path, And Network Policy.
• Implementation status: integration 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.