tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * generic net pointers
3 */
4
5#ifndef __NET_GENERIC_H__
6#define __NET_GENERIC_H__
7
8#include <linux/rcupdate.h>
9
10/*
11 * Generic net pointers are to be used by modules to put some private
12 * stuff on the struct net without explicit struct net modification
13 *
14 * The rules are simple:
15 * 1. set pernet_operations->id. After register_pernet_device you
16 * will have the id of your private pointer.
17 * 2. Either set pernet_operations->size (to have the code allocate and
18 * free a private structure pointed to from struct net ) or
19 * call net_assign_generic() to put the private data on the struct
20 * net (most preferably this should be done in the ->init callback
21 * of the ops registered);
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 unsigned int len;
31 struct rcu_head rcu;
32
33 void *ptr[0];
34};
35
36static inline void *net_generic(struct net *net, int id)
37{
38 struct net_generic *ng;
39 void *ptr;
40
41 rcu_read_lock();
42 ng = rcu_dereference(net->gen);
43 BUG_ON(id == 0 || id > ng->len);
44 ptr = ng->ptr[id - 1];
45 rcu_read_unlock();
46
47 return ptr;
48}
49
50extern int net_assign_generic(struct net *net, int id, void *data);
51#endif