1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * generic net pointers
4 */
5
6#ifndef __NET_GENERIC_H__
7#define __NET_GENERIC_H__
8
9#include <linux/bug.h>
10#include <linux/rcupdate.h>
11#include <net/net_namespace.h>
12
13/*
14 * Generic net pointers are to be used by modules to put some private
15 * stuff on the struct net without explicit struct net modification
16 *
17 * The rules are simple:
18 * 1. set pernet_operations->id. After register_pernet_device you
19 * will have the id of your private pointer.
20 * 2. set pernet_operations->size to have the code allocate and free
21 * a private structure pointed to from struct net.
22 * 3. do not change this pointer while the net is alive;
23 * 4. do not try to have any private reference on the net_generic object.
24 *
25 * After accomplishing all of the above, the private pointer can be
26 * accessed with the net_generic() call.
27 */
28
29struct net_generic {
30 union {
31 struct {
32 unsigned int len;
33 struct rcu_head rcu;
34 } s;
35
36 DECLARE_FLEX_ARRAY(void *, ptr);
37 };
38};
39
40static inline void *net_generic(const struct net *net, unsigned int id)
41{
42 struct net_generic *ng;
43 void *ptr;
44
45 rcu_read_lock();
46 ng = rcu_dereference(net->gen);
47 ptr = ng->ptr[id];
48 rcu_read_unlock();
49
50 return ptr;
51}
52#endif
53

source code of linux/include/net/netns/generic.h