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[1];
89 * __refcnt wants to be on a different cache line from
90 * input/output/ops or performance tanks badly
92 atomic_t __refcnt; /* client references */
94 unsigned long lastuse;
96 struct dst_entry *next;
97 struct rtable *rt_next;
98 struct rt6_info *rt6_next;
99 struct dn_route *dn_next;
106 dst_metric(const struct dst_entry *dst, int metric)
108 return dst->metrics[metric-1];
112 dst_feature(const struct dst_entry *dst, u32 feature)
114 return dst_metric(dst, RTAX_FEATURES) & feature;
117 static inline u32 dst_mtu(const struct dst_entry *dst)
119 u32 mtu = dst_metric(dst, RTAX_MTU);
121 * Alexey put it here, so ask him about it :)
127 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
128 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
130 return msecs_to_jiffies(dst_metric(dst, metric));
133 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
136 dst->metrics[metric-1] = jiffies_to_msecs(rtt);
140 dst_allfrag(const struct dst_entry *dst)
142 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG);
143 /* Yes, _exactly_. This is paranoia. */
149 dst_metric_locked(struct dst_entry *dst, int metric)
151 return dst_metric(dst, RTAX_LOCK) & (1<<metric);
154 static inline void dst_hold(struct dst_entry * dst)
157 * If your kernel compilation stops here, please check
158 * __pad_to_align_refcnt declaration in struct dst_entry
160 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
161 atomic_inc(&dst->__refcnt);
164 static inline void dst_use(struct dst_entry *dst, unsigned long time)
171 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
178 struct dst_entry * dst_clone(struct dst_entry * dst)
181 atomic_inc(&dst->__refcnt);
185 extern void dst_release(struct dst_entry *dst);
187 static inline void refdst_drop(unsigned long refdst)
189 if (!(refdst & SKB_DST_NOREF))
190 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
194 * skb_dst_drop - drops skb dst
197 * Drops dst reference count if a reference was taken.
199 static inline void skb_dst_drop(struct sk_buff *skb)
201 if (skb->_skb_refdst) {
202 refdst_drop(skb->_skb_refdst);
203 skb->_skb_refdst = 0UL;
207 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
209 nskb->_skb_refdst = oskb->_skb_refdst;
210 if (!(nskb->_skb_refdst & SKB_DST_NOREF))
211 dst_clone(skb_dst(nskb));
215 * skb_dst_force - makes sure skb dst is refcounted
218 * If dst is not yet refcounted, let's do it
220 static inline void skb_dst_force(struct sk_buff *skb)
222 if (skb_dst_is_noref(skb)) {
223 WARN_ON(!rcu_read_lock_held());
224 skb->_skb_refdst &= ~SKB_DST_NOREF;
225 dst_clone(skb_dst(skb));
231 * skb_tunnel_rx - prepare skb for rx reinsert
233 * @dev: tunnel device
235 * After decapsulation, packet is going to re-enter (netif_rx()) our stack,
236 * so make some cleanups, and perform accounting.
238 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
241 /* TODO : stats should be SMP safe */
242 dev->stats.rx_packets++;
243 dev->stats.rx_bytes += skb->len;
245 skb_set_queue_mapping(skb, 0);
250 /* Children define the path of the packet through the
251 * Linux networking. Thus, destinations are stackable.
254 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
256 struct dst_entry *child = skb_dst(skb)->child;
262 extern int dst_discard(struct sk_buff *skb);
263 extern void * dst_alloc(struct dst_ops * ops);
264 extern void __dst_free(struct dst_entry * dst);
265 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
267 static inline void dst_free(struct dst_entry * dst)
269 if (dst->obsolete > 1)
271 if (!atomic_read(&dst->__refcnt)) {
272 dst = dst_destroy(dst);
279 static inline void dst_rcu_free(struct rcu_head *head)
281 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
285 static inline void dst_confirm(struct dst_entry *dst)
288 neigh_confirm(dst->neighbour);
291 static inline void dst_link_failure(struct sk_buff *skb)
293 struct dst_entry *dst = skb_dst(skb);
294 if (dst && dst->ops && dst->ops->link_failure)
295 dst->ops->link_failure(skb);
298 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
300 unsigned long expires = jiffies + timeout;
305 if (dst->expires == 0 || time_before(expires, dst->expires))
306 dst->expires = expires;
309 /* Output packet to network from transport. */
310 static inline int dst_output(struct sk_buff *skb)
312 return skb_dst(skb)->output(skb);
315 /* Input packet from network to transport. */
316 static inline int dst_input(struct sk_buff *skb)
318 return skb_dst(skb)->input(skb);
321 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
324 dst = dst->ops->check(dst, cookie);
328 extern void dst_init(void);
330 /* Flags for xfrm_lookup flags argument. */
332 XFRM_LOOKUP_WAIT = 1 << 0,
333 XFRM_LOOKUP_ICMP = 1 << 1,
338 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
339 struct flowi *fl, struct sock *sk, int flags)
343 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
344 struct flowi *fl, struct sock *sk, int flags)
349 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
350 struct flowi *fl, struct sock *sk, int flags);
351 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
352 struct flowi *fl, struct sock *sk, int flags);
356 #endif /* _NET_DST_H */