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
36 struct sk_buff;
37
38 struct 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 unsigned int rate_tokens;
56 unsigned long rate_last; /* rate limiting for ICMP */
57
58 struct dst_entry *path;
59
60 struct neighbour *neighbour;
61 struct hh_cache *hh;
62 struct xfrm_state *xfrm;
63
64 int (*input)(struct sk_buff*);
65 int (*output)(struct sk_buff*);
66
67 struct dst_ops *ops;
68
69 u32 metrics[RTAX_MAX];
70
71 #ifdef CONFIG_NET_CLS_ROUTE
72 __u32 tclassid;
73 #endif
74
75 /*
76 * __refcnt wants to be on a different cache line from
77 * input/output/ops or performance tanks badly
78 */
79 atomic_t __refcnt; /* client references */
80 int __use;
81 unsigned long lastuse;
82 union {
83 struct dst_entry *next;
84 struct rtable *rt_next;
85 struct rt6_info *rt6_next;
86 struct dn_route *dn_next;
87 };
88 };
89
90
91 struct dst_ops
92 {
93 unsigned short family;
94 __be16 protocol;
95 unsigned gc_thresh;
96
97 int (*gc)(struct dst_ops *ops);
98 struct dst_entry * (*check)(struct dst_entry *, __u32 cookie);
99 void (*destroy)(struct dst_entry *);
100 void (*ifdown)(struct dst_entry *,
101 struct net_device *dev, int how);
102 struct dst_entry * (*negative_advice)(struct dst_entry *);
103 void (*link_failure)(struct sk_buff *);
104 void (*update_pmtu)(struct dst_entry *dst, u32 mtu);
105 int (*local_out)(struct sk_buff *skb);
106 int entry_size;
107
108 atomic_t entries;
109 struct kmem_cache *kmem_cachep;
110 struct net *dst_net;
111 };
112
113 #ifdef __KERNEL__
114
115 static inline u32
116 dst_metric(const struct dst_entry *dst, int metric)
117 {
118 return dst->metrics[metric-1];
119 }
120
121 static inline u32 dst_mtu(const struct dst_entry *dst)
122 {
123 u32 mtu = dst_metric(dst, RTAX_MTU);
124 /*
125 * Alexey put it here, so ask him about it :)
126 */
127 barrier();
128 return mtu;
129 }
130
131 static inline u32
132 dst_allfrag(const struct dst_entry *dst)
133 {
134 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
135 /* Yes, _exactly_. This is paranoia. */
136 barrier();
137 return ret;
138 }
139
140 static inline int
141 dst_metric_locked(struct dst_entry *dst, int metric)
142 {
143 return dst_metric(dst, RTAX_LOCK) & (1<<metric);
144 }
145
146 static inline void dst_hold(struct dst_entry * dst)
147 {
148 atomic_inc(&dst->__refcnt);
149 }
150
151 static inline void dst_use(struct dst_entry *dst, unsigned long time)
152 {
153 dst_hold(dst);
154 dst->__use++;
155 dst->lastuse = time;
156 }
157
158 static inline
159 struct dst_entry * dst_clone(struct dst_entry * dst)
160 {
161 if (dst)
162 atomic_inc(&dst->__refcnt);
163 return dst;
164 }
165
166 static inline
167 void dst_release(struct dst_entry * dst)
168 {
169 if (dst) {
170 WARN_ON(atomic_read(&dst->__refcnt) < 1);
171 smp_mb__before_atomic_dec();
172 atomic_dec(&dst->__refcnt);
173 }
174 }
175
176 /* Children define the path of the packet through the
177 * Linux networking. Thus, destinations are stackable.
178 */
179
180 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
181 {
182 struct dst_entry *child = dst_clone(dst->child);
183
184 dst_release(dst);
185 return child;
186 }
187
188 extern int dst_discard(struct sk_buff *skb);
189 extern void * dst_alloc(struct dst_ops * ops);
190 extern void __dst_free(struct dst_entry * dst);
191 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
192
193 static inline void dst_free(struct dst_entry * dst)
194 {
195 if (dst->obsolete > 1)
196 return;
197 if (!atomic_read(&dst->__refcnt)) {
198 dst = dst_destroy(dst);
199 if (!dst)
200 return;
201 }
202 __dst_free(dst);
203 }
204
205 static inline void dst_rcu_free(struct rcu_head *head)
206 {
207 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
208 dst_free(dst);
209 }
210
211 static inline void dst_confirm(struct dst_entry *dst)
212 {
213 if (dst)
214 neigh_confirm(dst->neighbour);
215 }
216
217 static inline void dst_negative_advice(struct dst_entry **dst_p)
218 {
219 struct dst_entry * dst = *dst_p;
220 if (dst && dst->ops->negative_advice)
221 *dst_p = dst->ops->negative_advice(dst);
222 }
223
224 static inline void dst_link_failure(struct sk_buff *skb)
225 {
226 struct dst_entry * dst = skb->dst;
227 if (dst && dst->ops && dst->ops->link_failure)
228 dst->ops->link_failure(skb);
229 }
230
231 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
232 {
233 unsigned long expires = jiffies + timeout;
234
235 if (expires == 0)
236 expires = 1;
237
238 if (dst->expires == 0 || time_before(expires, dst->expires))
239 dst->expires = expires;
240 }
241
242 /* Output packet to network from transport. */
243 static inline int dst_output(struct sk_buff *skb)
244 {
245 return skb->dst->output(skb);
246 }
247
248 /* Input packet from network to transport. */
249 static inline int dst_input(struct sk_buff *skb)
250 {
251 int err;
252
253 for (;;) {
254 err = skb->dst->input(skb);
255
256 if (likely(err == 0))
257 return err;
258 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
259 if (unlikely(err != NET_XMIT_BYPASS))
260 return err;
261 }
262 }
263
264 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
265 {
266 if (dst->obsolete)
267 dst = dst->ops->check(dst, cookie);
268 return dst;
269 }
270
271 extern void dst_init(void);
272
273 /* Flags for xfrm_lookup flags argument. */
274 enum {
275 XFRM_LOOKUP_WAIT = 1 << 0,
276 XFRM_LOOKUP_ICMP = 1 << 1,
277 };
278
279 struct flowi;
280 #ifndef CONFIG_XFRM
281 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
282 struct sock *sk, int flags)
283 {
284 return 0;
285 }
286 static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
287 struct sock *sk, int flags)
288 {
289 return 0;
290 }
291 #else
292 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
293 struct sock *sk, int flags);
294 extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
295 struct sock *sk, int flags);
296 #endif
297 #endif
298
299 #endif /* _NET_DST_H */
300
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