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 struct dst_entry
* (*negative_advice
)(struct dst_entry
*);
93 void (*link_failure
)(struct sk_buff
*);
94 void (*update_pmtu
)(struct dst_entry
*dst
, u32 mtu
);
95 int (*get_mss
)(struct dst_entry
*dst
, u32 mtu
);
99 kmem_cache_t
*kmem_cachep
;
105 dst_metric(struct dst_entry
*dst
, int metric
)
107 return dst
->metrics
[metric
-1];
111 dst_path_metric(struct dst_entry
*dst
, int metric
)
113 return dst
->path
->metrics
[metric
-1];
117 dst_pmtu(struct dst_entry
*dst
)
119 u32 mtu
= dst_path_metric(dst
, RTAX_MTU
);
120 /* Yes, _exactly_. This is paranoia. */
126 dst_metric_locked(struct dst_entry
*dst
, int metric
)
128 return dst_metric(dst
, RTAX_LOCK
) & (1<<metric
);
131 static inline void dst_hold(struct dst_entry
* dst
)
133 atomic_inc(&dst
->__refcnt
);
137 struct dst_entry
* dst_clone(struct dst_entry
* dst
)
140 atomic_inc(&dst
->__refcnt
);
145 void dst_release(struct dst_entry
* dst
)
148 if (atomic_read(&dst
->__refcnt
) < 1) {
149 printk("BUG: dst underflow %d: %p\n",
150 atomic_read(&dst
->__refcnt
),
151 current_text_addr());
153 atomic_dec(&dst
->__refcnt
);
157 /* Children define the path of the packet through the
158 * Linux networking. Thus, destinations are stackable.
161 static inline struct dst_entry
*dst_pop(struct dst_entry
*dst
)
163 struct dst_entry
*child
= dst_clone(dst
->child
);
169 extern void * dst_alloc(struct dst_ops
* ops
);
170 extern void __dst_free(struct dst_entry
* dst
);
171 extern struct dst_entry
*dst_destroy(struct dst_entry
* dst
);
173 static inline void dst_free(struct dst_entry
* dst
)
175 if (dst
->obsolete
> 1)
177 if (!atomic_read(&dst
->__refcnt
)) {
178 dst
= dst_destroy(dst
);
185 static inline void dst_confirm(struct dst_entry
*dst
)
188 neigh_confirm(dst
->neighbour
);
191 static inline void dst_negative_advice(struct dst_entry
**dst_p
)
193 struct dst_entry
* dst
= *dst_p
;
194 if (dst
&& dst
->ops
->negative_advice
)
195 *dst_p
= dst
->ops
->negative_advice(dst
);
198 static inline void dst_link_failure(struct sk_buff
*skb
)
200 struct dst_entry
* dst
= skb
->dst
;
201 if (dst
&& dst
->ops
&& dst
->ops
->link_failure
)
202 dst
->ops
->link_failure(skb
);
205 static inline void dst_set_expires(struct dst_entry
*dst
, int timeout
)
207 unsigned long expires
= jiffies
+ timeout
;
212 if (dst
->expires
== 0 || time_before(expires
, dst
->expires
))
213 dst
->expires
= expires
;
216 /* Output packet to network from transport. */
217 static inline int dst_output(struct sk_buff
*skb
)
222 err
= skb
->dst
->output(skb
);
224 if (likely(err
== 0))
226 if (unlikely(err
!= NET_XMIT_BYPASS
))
231 /* Input packet from network to transport. */
232 static inline int dst_input(struct sk_buff
*skb
)
237 err
= skb
->dst
->input(skb
);
239 if (likely(err
== 0))
241 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
242 if (unlikely(err
!= NET_XMIT_BYPASS
))
247 extern void dst_init(void);
250 extern int xfrm_lookup(struct dst_entry
**dst_p
, struct flowi
*fl
,
251 struct sock
*sk
, int flags
);
254 #endif /* _NET_DST_H */