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.
40 struct rcu_head rcu_head;
41 struct dst_entry *child;
42 struct net_device *dev;
48 #define DST_NOPOLICY 4
50 unsigned long expires;
52 unsigned short header_len; /* more space at head required */
53 unsigned short trailer_len; /* space to reserve at tail */
55 unsigned int rate_tokens;
56 unsigned long rate_last; /* rate limiting for ICMP */
58 struct dst_entry *path;
60 struct neighbour *neighbour;
63 struct xfrm_state *xfrm;
67 int (*input)(struct sk_buff*);
68 int (*output)(struct sk_buff*);
72 u32 metrics[RTAX_MAX];
74 #ifdef CONFIG_NET_CLS_ROUTE
82 * Align __refcnt to a 64 bytes alignment
83 * (L1_CACHE_SIZE would be too much)
86 long __pad_to_align_refcnt[2];
88 long __pad_to_align_refcnt[1];
91 * __refcnt wants to be on a different cache line from
92 * input/output/ops or performance tanks badly
94 atomic_t __refcnt; /* client references */
96 unsigned long lastuse;
98 struct dst_entry *next;
99 struct rtable *rt_next;
100 struct rt6_info *rt6_next;
101 struct dn_route *dn_next;
108 dst_metric(const struct dst_entry *dst, int metric)
110 return dst->metrics[metric-1];
114 dst_feature(const struct dst_entry *dst, u32 feature)
116 return (dst ? dst_metric(dst, RTAX_FEATURES) & feature : 0);
119 static inline u32 dst_mtu(const struct dst_entry *dst)
121 u32 mtu = dst_metric(dst, RTAX_MTU);
123 * Alexey put it here, so ask him about it :)
129 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
130 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
132 return msecs_to_jiffies(dst_metric(dst, metric));
135 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
138 dst->metrics[metric-1] = jiffies_to_msecs(rtt);
142 dst_allfrag(const struct dst_entry *dst)
144 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG);
145 /* Yes, _exactly_. This is paranoia. */
151 dst_metric_locked(struct dst_entry *dst, int metric)
153 return dst_metric(dst, RTAX_LOCK) & (1<<metric);
156 static inline void dst_hold(struct dst_entry * dst)
159 * If your kernel compilation stops here, please check
160 * __pad_to_align_refcnt declaration in struct dst_entry
162 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
163 atomic_inc(&dst->__refcnt);
166 static inline void dst_use(struct dst_entry *dst, unsigned long time)
174 struct dst_entry * dst_clone(struct dst_entry * dst)
177 atomic_inc(&dst->__refcnt);
181 extern void dst_release(struct dst_entry *dst);
182 static inline void skb_dst_drop(struct sk_buff *skb)
185 dst_release(skb_dst(skb));
189 /* Children define the path of the packet through the
190 * Linux networking. Thus, destinations are stackable.
193 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
195 struct dst_entry *child = dst_clone(dst->child);
201 extern int dst_discard(struct sk_buff *skb);
202 extern void * dst_alloc(struct dst_ops * ops);
203 extern void __dst_free(struct dst_entry * dst);
204 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
206 static inline void dst_free(struct dst_entry * dst)
208 if (dst->obsolete > 1)
210 if (!atomic_read(&dst->__refcnt)) {
211 dst = dst_destroy(dst);
218 static inline void dst_rcu_free(struct rcu_head *head)
220 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
224 static inline void dst_confirm(struct dst_entry *dst)
227 neigh_confirm(dst->neighbour);
230 static inline void dst_negative_advice(struct dst_entry **dst_p,
233 struct dst_entry * dst = *dst_p;
234 if (dst && dst->ops->negative_advice) {
235 *dst_p = dst->ops->negative_advice(dst);
238 extern void sk_reset_txq(struct sock *sk);
245 static inline void dst_link_failure(struct sk_buff *skb)
247 struct dst_entry *dst = skb_dst(skb);
248 if (dst && dst->ops && dst->ops->link_failure)
249 dst->ops->link_failure(skb);
252 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
254 unsigned long expires = jiffies + timeout;
259 if (dst->expires == 0 || time_before(expires, dst->expires))
260 dst->expires = expires;
263 /* Output packet to network from transport. */
264 static inline int dst_output(struct sk_buff *skb)
266 return skb_dst(skb)->output(skb);
269 /* Input packet from network to transport. */
270 static inline int dst_input(struct sk_buff *skb)
272 return skb_dst(skb)->input(skb);
275 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
278 dst = dst->ops->check(dst, cookie);
282 extern void dst_init(void);
284 /* Flags for xfrm_lookup flags argument. */
286 XFRM_LOOKUP_WAIT = 1 << 0,
287 XFRM_LOOKUP_ICMP = 1 << 1,
292 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
293 struct flowi *fl, struct sock *sk, int flags)
297 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
298 struct flowi *fl, struct sock *sk, int flags)
303 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
304 struct flowi *fl, struct sock *sk, int flags);
305 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
306 struct flowi *fl, struct sock *sk, int flags);
310 #endif /* _NET_DST_H */