/* SPDX-License-Identifier: GPL-2.0 *//* * generic net pointers */ #ifndef __NET_GENERIC_H__#define __NET_GENERIC_H__ #include <linux/bug.h>#include <linux/rcupdate.h>#include <net/net_namespace.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 {	union {		struct {			unsigned int len;			struct rcu_head rcu;		} s; 		DECLARE_FLEX_ARRAY(void *, ptr);	};}; static inline void *net_generic(const struct net *net, unsigned int id){	struct net_generic *ng;	void *ptr; 	rcu_read_lock();	ng = rcu_dereference(net->gen);	ptr = ng->ptr[id];	rcu_read_unlock(); 	return ptr;}#endif