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. set pernet_operations->size to have the code allocate and free 18 * a private structure pointed to from struct net. 19 * 3. do not change this pointer while the net is alive; 20 * 4. do not try to have any private reference on the net_generic object. 21 * 22 * After accomplishing all of the above, the private pointer can be 23 * accessed with the net_generic() call. 24 */ 25 26struct net_generic { 27 unsigned int len; 28 struct rcu_head rcu; 29 30 void *ptr[0]; 31}; 32 33static inline void *net_generic(struct net *net, int id) 34{ 35 struct net_generic *ng; 36 void *ptr; 37 38 rcu_read_lock(); 39 ng = rcu_dereference(net->gen); 40 BUG_ON(id == 0 || id > ng->len); 41 ptr = ng->ptr[id - 1]; 42 rcu_read_unlock(); 43 44 return ptr; 45} 46#endif 47