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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 unsigned long expires;
51
52 unsigned short header_len; /* more space at head required */
53 unsigned short trailer_len; /* space to reserve at tail */
54
55 u32 metrics[RTAX_MAX];
56 struct dst_entry *path;
57
58 unsigned long rate_last; /* rate limiting for ICMP */
59 unsigned int rate_tokens;
60
61#ifdef CONFIG_NET_CLS_ROUTE
62 __u32 tclassid;
63#endif
64
65 struct neighbour *neighbour;
66 struct hh_cache *hh;
67 struct xfrm_state *xfrm;
68
69 int (*input)(struct sk_buff*);
70 int (*output)(struct sk_buff*);
71
72 struct dst_ops *ops;
73
74 unsigned long lastuse;
75 atomic_t __refcnt; /* client references */
76 int __use;
77 union {
78 struct dst_entry *next;
79 struct rtable *rt_next;
80 struct rt6_info *rt6_next;
81 struct dn_route *dn_next;
82 };
83};
84
85
86struct dst_ops
87{
88 unsigned short family;
89 __be16 protocol;
90 unsigned gc_thresh;
91
92 int (*gc)(struct dst_ops *ops);
93 struct dst_entry * (*check)(struct dst_entry *, __u32 cookie);
94 void (*destroy)(struct dst_entry *);
95 void (*ifdown)(struct dst_entry *,
96 struct net_device *dev, int how);
97 struct dst_entry * (*negative_advice)(struct dst_entry *);
98 void (*link_failure)(struct sk_buff *);
99 void (*update_pmtu)(struct dst_entry *dst, u32 mtu);
100 int (*local_out)(struct sk_buff *skb);
101 int entry_size;
102
103 atomic_t entries;
104 struct kmem_cache *kmem_cachep;
105 struct net *dst_net;
106};
107
108#ifdef __KERNEL__
109
110static inline u32
111dst_metric(const struct dst_entry *dst, int metric)
112{
113 return dst->metrics[metric-1];
114}
115
116static inline u32 dst_mtu(const struct dst_entry *dst)
117{
118 u32 mtu = dst_metric(dst, RTAX_MTU);
119 /*
120 * Alexey put it here, so ask him about it :)
121 */
122 barrier();
123 return mtu;
124}
125
126static inline u32
127dst_allfrag(const struct dst_entry *dst)
128{
129 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
130 /* Yes, _exactly_. This is paranoia. */
131 barrier();
132 return ret;
133}
134
135static inline int
136dst_metric_locked(struct dst_entry *dst, int metric)
137{
138 return dst_metric(dst, RTAX_LOCK) & (1<<metric);
139}
140
141static inline void dst_hold(struct dst_entry * dst)
142{
143 atomic_inc(&dst->__refcnt);
144}
145
146static inline void dst_use(struct dst_entry *dst, unsigned long time)
147{
148 dst_hold(dst);
149 dst->__use++;
150 dst->lastuse = time;
151}
152
153static inline
154struct dst_entry * dst_clone(struct dst_entry * dst)
155{
156 if (dst)
157 atomic_inc(&dst->__refcnt);
158 return dst;
159}
160
161static inline
162void dst_release(struct dst_entry * dst)
163{
164 if (dst) {
165 WARN_ON(atomic_read(&dst->__refcnt) < 1);
166 smp_mb__before_atomic_dec();
167 atomic_dec(&dst->__refcnt);
168 }
169}
170
171/* Children define the path of the packet through the
172 * Linux networking. Thus, destinations are stackable.
173 */
174
175static inline struct dst_entry *dst_pop(struct dst_entry *dst)
176{
177 struct dst_entry *child = dst_clone(dst->child);
178
179 dst_release(dst);
180 return child;
181}
182
183extern int dst_discard(struct sk_buff *skb);
184extern void * dst_alloc(struct dst_ops * ops);
185extern void __dst_free(struct dst_entry * dst);
186extern struct dst_entry *dst_destroy(struct dst_entry * dst);
187
188static inline void dst_free(struct dst_entry * dst)
189{
190 if (dst->obsolete > 1)
191 return;
192 if (!atomic_read(&dst->__refcnt)) {
193 dst = dst_destroy(dst);
194 if (!dst)
195 return;
196 }
197 __dst_free(dst);
198}
199
200static inline void dst_rcu_free(struct rcu_head *head)
201{
202 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
203 dst_free(dst);
204}
205
206static inline void dst_confirm(struct dst_entry *dst)
207{
208 if (dst)
209 neigh_confirm(dst->neighbour);
210}
211
212static inline void dst_negative_advice(struct dst_entry **dst_p)
213{
214 struct dst_entry * dst = *dst_p;
215 if (dst && dst->ops->negative_advice)
216 *dst_p = dst->ops->negative_advice(dst);
217}
218
219static inline void dst_link_failure(struct sk_buff *skb)
220{
221 struct dst_entry * dst = skb->dst;
222 if (dst && dst->ops && dst->ops->link_failure)
223 dst->ops->link_failure(skb);
224}
225
226static inline void dst_set_expires(struct dst_entry *dst, int timeout)
227{
228 unsigned long expires = jiffies + timeout;
229
230 if (expires == 0)
231 expires = 1;
232
233 if (dst->expires == 0 || time_before(expires, dst->expires))
234 dst->expires = expires;
235}
236
237/* Output packet to network from transport. */
238static inline int dst_output(struct sk_buff *skb)
239{
240 return skb->dst->output(skb);
241}
242
243/* Input packet from network to transport. */
244static inline int dst_input(struct sk_buff *skb)
245{
246 int err;
247
248 for (;;) {
249 err = skb->dst->input(skb);
250
251 if (likely(err == 0))
252 return err;
253 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
254 if (unlikely(err != NET_XMIT_BYPASS))
255 return err;
256 }
257}
258
259static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
260{
261 if (dst->obsolete)
262 dst = dst->ops->check(dst, cookie);
263 return dst;
264}
265
266extern void dst_init(void);
267
268/* Flags for xfrm_lookup flags argument. */
269enum {
270 XFRM_LOOKUP_WAIT = 1 << 0,
271 XFRM_LOOKUP_ICMP = 1 << 1,
272};
273
274struct flowi;
275#ifndef CONFIG_XFRM
276static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
277 struct sock *sk, int flags)
278{
279 return 0;
280}
281static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
282 struct sock *sk, int flags)
283{
284 return 0;
285}
286#else
287extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
288 struct sock *sk, int flags);
289extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
290 struct sock *sk, int flags);
291#endif
292#endif
293
294#endif /* _NET_DST_H */