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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 { | |
6af2d5ff AD |
28 | union { |
29 | struct { | |
30 | unsigned int len; | |
31 | struct rcu_head rcu; | |
32 | } s; | |
33 | ||
34 | void *ptr[0]; | |
35 | }; | |
dec827d1 PE |
36 | }; |
37 | ||
c7d03a00 | 38 | static inline void *net_generic(const struct net *net, unsigned int id) |
dec827d1 PE |
39 | { |
40 | struct net_generic *ng; | |
41 | void *ptr; | |
42 | ||
43 | rcu_read_lock(); | |
44 | ng = rcu_dereference(net->gen); | |
6af2d5ff | 45 | ptr = ng->ptr[id]; |
dec827d1 PE |
46 | rcu_read_unlock(); |
47 | ||
48 | return ptr; | |
49 | } | |
dec827d1 | 50 | #endif |