1/*
2 * net/dst.h	Protocol independent destination cache definitions.
3 *
4 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
5 *
6 */
7
8#ifndef _NET_DST_H
9#define _NET_DST_H
10
11#include <linux/netdevice.h>
12#include <linux/rtnetlink.h>
13#include <linux/rcupdate.h>
14#include <linux/jiffies.h>
15#include <net/neighbour.h>
16#include <asm/processor.h>
17
18/*
19 * 0 - no debugging messages
20 * 1 - rare events and bugs (default)
21 * 2 - trace mode.
22 */
23#define RT_CACHE_DEBUG		0
24
25#define DST_GC_MIN	(HZ/10)
26#define DST_GC_INC	(HZ/2)
27#define DST_GC_MAX	(120*HZ)
28
29/* Each dst_entry has reference count and sits in some parent list(s).
30 * When it is removed from parent list, it is "freed" (dst_free).
31 * After this it enters dead state (dst->obsolete > 0) and if its refcnt
32 * is zero, it can be destroyed immediately, otherwise it is added
33 * to gc list and garbage collector periodically checks the refcnt.
34 */
35
36struct sk_buff;
37
38struct dst_entry
39{
40	struct rcu_head		rcu_head;
41	struct dst_entry	*child;
42	struct net_device       *dev;
43	short			error;
44	short			obsolete;
45	int			flags;
46#define DST_HOST		1
47#define DST_NOXFRM		2
48#define DST_NOPOLICY		4
49#define DST_NOHASH		8
50#define DST_BALANCED            0x10
51	unsigned long		expires;
52
53	unsigned short		header_len;	/* more space at head required */
54	unsigned short		nfheader_len;	/* more non-fragment space at head required */
55	unsigned short		trailer_len;	/* space to reserve at tail */
56
57	u32			metrics[RTAX_MAX];
58	struct dst_entry	*path;
59
60	unsigned long		rate_last;	/* rate limiting for ICMP */
61	unsigned long		rate_tokens;
62
63	struct neighbour	*neighbour;
64	struct hh_cache		*hh;
65	struct xfrm_state	*xfrm;
66
67	int			(*input)(struct sk_buff*);
68	int			(*output)(struct sk_buff*);
69
70#ifdef CONFIG_NET_CLS_ROUTE
71	__u32			tclassid;
72#endif
73
74	struct  dst_ops	        *ops;
75
76	unsigned long		lastuse;
77	atomic_t		__refcnt;	/* client references	*/
78	int			__use;
79	union {
80		struct dst_entry *next;
81		struct rtable    *rt_next;
82		struct rt6_info   *rt6_next;
83		struct dn_route  *dn_next;
84	};
85	char			info[0];
86};
87
88
89struct dst_ops
90{
91	unsigned short		family;
92	__be16			protocol;
93	unsigned		gc_thresh;
94
95	int			(*gc)(void);
96	struct dst_entry *	(*check)(struct dst_entry *, __u32 cookie);
97	void			(*destroy)(struct dst_entry *);
98	void			(*ifdown)(struct dst_entry *,
99					  struct net_device *dev, int how);
100	struct dst_entry *	(*negative_advice)(struct dst_entry *);
101	void			(*link_failure)(struct sk_buff *);
102	void			(*update_pmtu)(struct dst_entry *dst, u32 mtu);
103	int			entry_size;
104
105	atomic_t		entries;
106	struct kmem_cache 		*kmem_cachep;
107};
108
109#ifdef __KERNEL__
110
111static inline u32
112dst_metric(const struct dst_entry *dst, int metric)
113{
114	return dst->metrics[metric-1];
115}
116
117static inline u32 dst_mtu(const struct dst_entry *dst)
118{
119	u32 mtu = dst_metric(dst, RTAX_MTU);
120	/*
121	 * Alexey put it here, so ask him about it :)
122	 */
123	barrier();
124	return mtu;
125}
126
127static inline u32
128dst_allfrag(const struct dst_entry *dst)
129{
130	int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
131	/* Yes, _exactly_. This is paranoia. */
132	barrier();
133	return ret;
134}
135
136static inline int
137dst_metric_locked(struct dst_entry *dst, int metric)
138{
139	return dst_metric(dst, RTAX_LOCK) & (1<<metric);
140}
141
142static inline void dst_hold(struct dst_entry * dst)
143{
144	atomic_inc(&dst->__refcnt);
145}
146
147static inline
148struct dst_entry * dst_clone(struct dst_entry * dst)
149{
150	if (dst)
151		atomic_inc(&dst->__refcnt);
152	return dst;
153}
154
155static inline
156void dst_release(struct dst_entry * dst)
157{
158	if (dst) {
159		WARN_ON(atomic_read(&dst->__refcnt) < 1);
160		smp_mb__before_atomic_dec();
161		atomic_dec(&dst->__refcnt);
162	}
163}
164
165/* Children define the path of the packet through the
166 * Linux networking.  Thus, destinations are stackable.
167 */
168
169static inline struct dst_entry *dst_pop(struct dst_entry *dst)
170{
171	struct dst_entry *child = dst_clone(dst->child);
172
173	dst_release(dst);
174	return child;
175}
176
177extern void * dst_alloc(struct dst_ops * ops);
178extern void __dst_free(struct dst_entry * dst);
179extern struct dst_entry *dst_destroy(struct dst_entry * dst);
180
181static inline void dst_free(struct dst_entry * dst)
182{
183	if (dst->obsolete > 1)
184		return;
185	if (!atomic_read(&dst->__refcnt)) {
186		dst = dst_destroy(dst);
187		if (!dst)
188			return;
189	}
190	__dst_free(dst);
191}
192
193static inline void dst_rcu_free(struct rcu_head *head)
194{
195	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
196	dst_free(dst);
197}
198
199static inline void dst_confirm(struct dst_entry *dst)
200{
201	if (dst)
202		neigh_confirm(dst->neighbour);
203}
204
205static inline void dst_negative_advice(struct dst_entry **dst_p)
206{
207	struct dst_entry * dst = *dst_p;
208	if (dst && dst->ops->negative_advice)
209		*dst_p = dst->ops->negative_advice(dst);
210}
211
212static inline void dst_link_failure(struct sk_buff *skb)
213{
214	struct dst_entry * dst = skb->dst;
215	if (dst && dst->ops && dst->ops->link_failure)
216		dst->ops->link_failure(skb);
217}
218
219static inline void dst_set_expires(struct dst_entry *dst, int timeout)
220{
221	unsigned long expires = jiffies + timeout;
222
223	if (expires == 0)
224		expires = 1;
225
226	if (dst->expires == 0 || time_before(expires, dst->expires))
227		dst->expires = expires;
228}
229
230/* Output packet to network from transport.  */
231static inline int dst_output(struct sk_buff *skb)
232{
233	return skb->dst->output(skb);
234}
235
236/* Input packet from network to transport.  */
237static inline int dst_input(struct sk_buff *skb)
238{
239	int err;
240
241	for (;;) {
242		err = skb->dst->input(skb);
243
244		if (likely(err == 0))
245			return err;
246		/* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
247		if (unlikely(err != NET_XMIT_BYPASS))
248			return err;
249	}
250}
251
252static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
253{
254	if (dst->obsolete)
255		dst = dst->ops->check(dst, cookie);
256	return dst;
257}
258
259extern void		dst_init(void);
260
261struct flowi;
262#ifndef CONFIG_XFRM
263static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
264		       struct sock *sk, int flags)
265{
266	return 0;
267}
268static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
269				struct sock *sk, int flags)
270{
271	return 0;
272}
273#else
274extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
275		       struct sock *sk, int flags);
276extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
277			 struct sock *sk, int flags);
278#endif
279#endif
280
281#endif /* _NET_DST_H */
282