[linux-block.git] / include / net / netns / generic.h

/*
 * generic net pointers
 */

#ifndef __NET_GENERIC_H__
#define __NET_GENERIC_H__

#include <linux/bug.h>
#include <linux/rcupdate.h>

/*
 * Generic net pointers are to be used by modules to put some private
 * stuff on the struct net without explicit struct net modification
 *
 * The rules are simple:
 * 1. set pernet_operations->id.  After register_pernet_device you
 *    will have the id of your private pointer.
 * 2. set pernet_operations->size to have the code allocate and free
 *    a private structure pointed to from struct net.
 * 3. do not change this pointer while the net is alive;
 * 4. do not try to have any private reference on the net_generic object.
 *
 * After accomplishing all of the above, the private pointer can be
 * accessed with the net_generic() call.
 */

struct net_generic {
	unsigned int len;
	struct rcu_head rcu;

	void *ptr[0];
};

static inline void *net_generic(const struct net *net, int id)
{
	struct net_generic *ng;
	void *ptr;

	rcu_read_lock();
	ng = rcu_dereference(net->gen);
	BUG_ON(id == 0 || id > ng->len);
	ptr = ng->ptr[id - 1];
	rcu_read_unlock();

	BUG_ON(!ptr);
	return ptr;
}
#endif
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
65c0cfaf EB	17	* will have the id of your private pointer.
05fceb4a JP	18	* 2. set pernet_operations->size to have the code allocate and free
05fceb4a JP	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;
dec827d1 PE	47	}
dec827d1	48	#endif