2 * net/dst.h Protocol independent destination cache definitions.
4 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
11 #include <net/dst_ops.h>
12 #include <linux/netdevice.h>
13 #include <linux/rtnetlink.h>
14 #include <linux/rcupdate.h>
15 #include <linux/jiffies.h>
16 #include <net/neighbour.h>
17 #include <asm/processor.h>
20 * 0 - no debugging messages
21 * 1 - rare events and bugs (default)
24 #define RT_CACHE_DEBUG 0
26 #define DST_GC_MIN (HZ/10)
27 #define DST_GC_INC (HZ/2)
28 #define DST_GC_MAX (120*HZ)
30 /* Each dst_entry has reference count and sits in some parent list(s).
31 * When it is removed from parent list, it is "freed" (dst_free).
32 * After this it enters dead state (dst->obsolete > 0) and if its refcnt
33 * is zero, it can be destroyed immediately, otherwise it is added
34 * to gc list and garbage collector periodically checks the refcnt.
41 struct rcu_head rcu_head;
42 struct dst_entry *child;
43 struct net_device *dev;
49 #define DST_NOPOLICY 4
51 unsigned long expires;
53 unsigned short header_len; /* more space at head required */
54 unsigned short trailer_len; /* space to reserve at tail */
56 unsigned int rate_tokens;
57 unsigned long rate_last; /* rate limiting for ICMP */
59 struct dst_entry *path;
61 struct neighbour *neighbour;
64 struct xfrm_state *xfrm;
68 int (*input)(struct sk_buff*);
69 int (*output)(struct sk_buff*);
73 u32 metrics[RTAX_MAX];
75 #ifdef CONFIG_NET_CLS_ROUTE
83 * Align __refcnt to a 64 bytes alignment
84 * (L1_CACHE_SIZE would be too much)
87 long __pad_to_align_refcnt[2];
89 long __pad_to_align_refcnt[1];
92 * __refcnt wants to be on a different cache line from
93 * input/output/ops or performance tanks badly
95 atomic_t __refcnt; /* client references */
97 unsigned long lastuse;
99 struct dst_entry *next;
100 struct rtable *rt_next;
101 struct rt6_info *rt6_next;
102 struct dn_route *dn_next;
109 dst_metric(const struct dst_entry *dst, int metric)
111 return dst->metrics[metric-1];
114 static inline u32 dst_mtu(const struct dst_entry *dst)
116 u32 mtu = dst_metric(dst, RTAX_MTU);
118 * Alexey put it here, so ask him about it :)
124 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
125 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
127 return msecs_to_jiffies(dst_metric(dst, metric));
130 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
133 dst->metrics[metric-1] = jiffies_to_msecs(rtt);
137 dst_allfrag(const struct dst_entry *dst)
139 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
140 /* Yes, _exactly_. This is paranoia. */
146 dst_metric_locked(struct dst_entry *dst, int metric)
148 return dst_metric(dst, RTAX_LOCK) & (1<<metric);
151 static inline void dst_hold(struct dst_entry * dst)
154 * If your kernel compilation stops here, please check
155 * __pad_to_align_refcnt declaration in struct dst_entry
157 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
158 atomic_inc(&dst->__refcnt);
161 static inline void dst_use(struct dst_entry *dst, unsigned long time)
169 struct dst_entry * dst_clone(struct dst_entry * dst)
172 atomic_inc(&dst->__refcnt);
176 extern void dst_release(struct dst_entry *dst);
177 static inline void skb_dst_drop(struct sk_buff *skb)
180 dst_release(skb_dst(skb));
184 /* Children define the path of the packet through the
185 * Linux networking. Thus, destinations are stackable.
188 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
190 struct dst_entry *child = dst_clone(dst->child);
196 extern int dst_discard(struct sk_buff *skb);
197 extern void * dst_alloc(struct dst_ops * ops);
198 extern void __dst_free(struct dst_entry * dst);
199 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
201 static inline void dst_free(struct dst_entry * dst)
203 if (dst->obsolete > 1)
205 if (!atomic_read(&dst->__refcnt)) {
206 dst = dst_destroy(dst);
213 static inline void dst_rcu_free(struct rcu_head *head)
215 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
219 static inline void dst_confirm(struct dst_entry *dst)
222 neigh_confirm(dst->neighbour);
225 static inline void dst_negative_advice(struct dst_entry **dst_p)
227 struct dst_entry * dst = *dst_p;
228 if (dst && dst->ops->negative_advice)
229 *dst_p = dst->ops->negative_advice(dst);
232 static inline void dst_link_failure(struct sk_buff *skb)
234 struct dst_entry *dst = skb_dst(skb);
235 if (dst && dst->ops && dst->ops->link_failure)
236 dst->ops->link_failure(skb);
239 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
241 unsigned long expires = jiffies + timeout;
246 if (dst->expires == 0 || time_before(expires, dst->expires))
247 dst->expires = expires;
250 /* Output packet to network from transport. */
251 static inline int dst_output(struct sk_buff *skb)
253 return skb_dst(skb)->output(skb);
256 /* Input packet from network to transport. */
257 static inline int dst_input(struct sk_buff *skb)
259 return skb_dst(skb)->input(skb);
262 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
265 dst = dst->ops->check(dst, cookie);
269 extern void dst_init(void);
271 /* Flags for xfrm_lookup flags argument. */
273 XFRM_LOOKUP_WAIT = 1 << 0,
274 XFRM_LOOKUP_ICMP = 1 << 1,
279 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
280 struct flowi *fl, struct sock *sk, int flags)
284 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
285 struct flowi *fl, struct sock *sk, int flags)
290 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
291 struct flowi *fl, struct sock *sk, int flags);
292 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
293 struct flowi *fl, struct sock *sk, int flags);
297 #endif /* _NET_DST_H */