]>
Commit | Line | Data |
---|---|---|
dec827d1 PE |
1 | /* |
2 | * generic net pointers | |
3 | */ | |
4 | ||
5 | #ifndef __NET_GENERIC_H__ | |
6 | #define __NET_GENERIC_H__ | |
7 | ||
187f1882 | 8 | #include <linux/bug.h> |
dec827d1 PE |
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: | |
65c0cfaf EB |
16 | * 1. set pernet_operations->id. After register_pernet_device you |
17 | * will have the id of your private pointer. | |
05fceb4a JP |
18 | * 2. set pernet_operations->size to have the code allocate and free |
19 | * a private structure pointed to from struct net. | |
dec827d1 PE |
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 | ||
27 | struct net_generic { | |
28 | unsigned int len; | |
29 | struct rcu_head rcu; | |
30 | ||
31 | void *ptr[0]; | |
32 | }; | |
33 | ||
20a95a21 | 34 | static inline void *net_generic(const struct net *net, int id) |
dec827d1 PE |
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 | ||
5ee4433e | 45 | BUG_ON(!ptr); |
dec827d1 PE |
46 | return ptr; |
47 | } | |
dec827d1 | 48 | #endif |