2 * net/dst.h Protocol independent destination cache definitions.
4 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
11 #include <linux/config.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>
19 * 0 - no debugging messages
20 * 1 - rare events and bugs (default)
23 #define RT_CACHE_DEBUG 0
25 #define DST_GC_MIN (HZ/10)
26 #define DST_GC_INC (HZ/2)
27 #define DST_GC_MAX (120*HZ)
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.
40 struct dst_entry *next;
41 atomic_t __refcnt; /* client references */
43 struct dst_entry *child;
44 struct net_device *dev;
49 #define DST_NOPOLICY 4
51 unsigned long lastuse;
52 unsigned long expires;
54 unsigned short header_len; /* more space at head required */
55 unsigned short trailer_len; /* space to reserve at tail */
57 u32 metrics[RTAX_MAX];
58 struct dst_entry *path;
60 unsigned long rate_last; /* rate limiting for ICMP */
61 unsigned long rate_tokens;
65 struct neighbour *neighbour;
67 struct xfrm_state *xfrm;
69 int (*input)(struct sk_buff*);
70 int (*output)(struct sk_buff*);
72 #ifdef CONFIG_NET_CLS_ROUTE
77 struct rcu_head rcu_head;
85 unsigned short family;
86 unsigned short protocol;
90 struct dst_entry * (*check)(struct dst_entry *, __u32 cookie);
91 void (*destroy)(struct dst_entry *);
92 void (*ifdown)(struct dst_entry *,
93 struct net_device *dev, int how);
94 struct dst_entry * (*negative_advice)(struct dst_entry *);
95 void (*link_failure)(struct sk_buff *);
96 void (*update_pmtu)(struct dst_entry *dst, u32 mtu);
97 int (*get_mss)(struct dst_entry *dst, u32 mtu);
101 kmem_cache_t *kmem_cachep;
107 dst_metric(const struct dst_entry *dst, int metric)
109 return dst->metrics[metric-1];
113 dst_path_metric(const struct dst_entry *dst, int metric)
115 return dst->path->metrics[metric-1];
119 dst_pmtu(const struct dst_entry *dst)
121 u32 mtu = dst_path_metric(dst, RTAX_MTU);
122 /* Yes, _exactly_. This is paranoia. */
128 dst_metric_locked(struct dst_entry *dst, int metric)
130 return dst_metric(dst, RTAX_LOCK) & (1<<metric);
133 static inline void dst_hold(struct dst_entry * dst)
135 atomic_inc(&dst->__refcnt);
139 struct dst_entry * dst_clone(struct dst_entry * dst)
142 atomic_inc(&dst->__refcnt);
147 void dst_release(struct dst_entry * dst)
150 WARN_ON(atomic_read(&dst->__refcnt) < 1);
151 smp_mb__before_atomic_dec();
152 atomic_dec(&dst->__refcnt);
156 /* Children define the path of the packet through the
157 * Linux networking. Thus, destinations are stackable.
160 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
162 struct dst_entry *child = dst_clone(dst->child);
168 extern void * dst_alloc(struct dst_ops * ops);
169 extern void __dst_free(struct dst_entry * dst);
170 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
172 static inline void dst_free(struct dst_entry * dst)
174 if (dst->obsolete > 1)
176 if (!atomic_read(&dst->__refcnt)) {
177 dst = dst_destroy(dst);
184 static inline void dst_rcu_free(struct rcu_head *head)
186 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
190 static inline void dst_confirm(struct dst_entry *dst)
193 neigh_confirm(dst->neighbour);
196 static inline void dst_negative_advice(struct dst_entry **dst_p)
198 struct dst_entry * dst = *dst_p;
199 if (dst && dst->ops->negative_advice)
200 *dst_p = dst->ops->negative_advice(dst);
203 static inline void dst_link_failure(struct sk_buff *skb)
205 struct dst_entry * dst = skb->dst;
206 if (dst && dst->ops && dst->ops->link_failure)
207 dst->ops->link_failure(skb);
210 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
212 unsigned long expires = jiffies + timeout;
217 if (dst->expires == 0 || time_before(expires, dst->expires))
218 dst->expires = expires;
221 /* Output packet to network from transport. */
222 static inline int dst_output(struct sk_buff *skb)
227 err = skb->dst->output(skb);
229 if (likely(err == 0))
231 if (unlikely(err != NET_XMIT_BYPASS))
236 /* Input packet from network to transport. */
237 static inline int dst_input(struct sk_buff *skb)
242 err = skb->dst->input(skb);
244 if (likely(err == 0))
246 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
247 if (unlikely(err != NET_XMIT_BYPASS))
252 extern void dst_init(void);
256 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
257 struct sock *sk, int flags)
262 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
263 struct sock *sk, int flags);
267 #endif /* _NET_DST_H */