1/*
 2 * generic net pointers
 3 */
 4
 5#ifndef __NET_GENERIC_H__
 6#define __NET_GENERIC_H__
 7
 8#include <linux/bug.h>
 9#include <linux/rcupdate.h>
 
10
11/*
12 * Generic net pointers are to be used by modules to put some private
13 * stuff on the struct net without explicit struct net modification
14 *
15 * The rules are simple:
16 * 1. set pernet_operations->id.  After register_pernet_device you
17 *    will have the id of your private pointer.
18 * 2. set pernet_operations->size to have the code allocate and free
19 *    a private structure pointed to from struct net.
20 * 3. do not change this pointer while the net is alive;
21 * 4. do not try to have any private reference on the net_generic object.
22 *
23 * After accomplishing all of the above, the private pointer can be
24 * accessed with the net_generic() call.
25 */
26
27struct net_generic {
28	unsigned int len;
29	struct rcu_head rcu;
 
 
 
30
31	void *ptr[0];
 
32};
33
34static inline void *net_generic(const struct net *net, int id)
35{
36	struct net_generic *ng;
37	void *ptr;
38
39	rcu_read_lock();
40	ng = rcu_dereference(net->gen);
41	BUG_ON(id == 0 || id > ng->len);
42	ptr = ng->ptr[id - 1];
43	rcu_read_unlock();
44
45	BUG_ON(!ptr);
46	return ptr;
47}
48#endif

 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