xref: /openbmc/linux/include/net/dst.h (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * net/dst.h	Protocol independent destination cache definitions.
3  *
4  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
5  *
6  */
7 
8 #ifndef _NET_DST_H
9 #define _NET_DST_H
10 
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>
17 
18 /*
19  * 0 - no debugging messages
20  * 1 - rare events and bugs (default)
21  * 2 - trace mode.
22  */
23 #define RT_CACHE_DEBUG		0
24 
25 #define DST_GC_MIN	(HZ/10)
26 #define DST_GC_INC	(HZ/2)
27 #define DST_GC_MAX	(120*HZ)
28 
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.
34  */
35 
36 struct sk_buff;
37 
38 struct dst_entry
39 {
40 	struct dst_entry        *next;
41 	atomic_t		__refcnt;	/* client references	*/
42 	int			__use;
43 	struct dst_entry	*child;
44 	struct net_device       *dev;
45 	short			error;
46 	short			obsolete;
47 	int			flags;
48 #define DST_HOST		1
49 #define DST_NOXFRM		2
50 #define DST_NOPOLICY		4
51 #define DST_NOHASH		8
52 #define DST_BALANCED            0x10
53 	unsigned long		lastuse;
54 	unsigned long		expires;
55 
56 	unsigned short		header_len;	/* more space at head required */
57 	unsigned short		trailer_len;	/* space to reserve at tail */
58 
59 	u32			metrics[RTAX_MAX];
60 	struct dst_entry	*path;
61 
62 	unsigned long		rate_last;	/* rate limiting for ICMP */
63 	unsigned long		rate_tokens;
64 
65 	struct neighbour	*neighbour;
66 	struct hh_cache		*hh;
67 	struct xfrm_state	*xfrm;
68 
69 	int			(*input)(struct sk_buff*);
70 	int			(*output)(struct sk_buff*);
71 
72 #ifdef CONFIG_NET_CLS_ROUTE
73 	__u32			tclassid;
74 #endif
75 
76 	struct  dst_ops	        *ops;
77 	struct rcu_head		rcu_head;
78 
79 	char			info[0];
80 };
81 
82 
83 struct dst_ops
84 {
85 	unsigned short		family;
86 	unsigned short		protocol;
87 	unsigned		gc_thresh;
88 
89 	int			(*gc)(void);
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			entry_size;
98 
99 	atomic_t		entries;
100 	kmem_cache_t 		*kmem_cachep;
101 };
102 
103 #ifdef __KERNEL__
104 
105 static inline u32
106 dst_metric(const struct dst_entry *dst, int metric)
107 {
108 	return dst->metrics[metric-1];
109 }
110 
111 static inline u32 dst_mtu(const struct dst_entry *dst)
112 {
113 	u32 mtu = dst_metric(dst, RTAX_MTU);
114 	/*
115 	 * Alexey put it here, so ask him about it :)
116 	 */
117 	barrier();
118 	return mtu;
119 }
120 
121 static inline u32
122 dst_allfrag(const struct dst_entry *dst)
123 {
124 	int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
125 	/* Yes, _exactly_. This is paranoia. */
126 	barrier();
127 	return ret;
128 }
129 
130 static inline int
131 dst_metric_locked(struct dst_entry *dst, int metric)
132 {
133 	return dst_metric(dst, RTAX_LOCK) & (1<<metric);
134 }
135 
136 static inline void dst_hold(struct dst_entry * dst)
137 {
138 	atomic_inc(&dst->__refcnt);
139 }
140 
141 static inline
142 struct dst_entry * dst_clone(struct dst_entry * dst)
143 {
144 	if (dst)
145 		atomic_inc(&dst->__refcnt);
146 	return dst;
147 }
148 
149 static inline
150 void dst_release(struct dst_entry * dst)
151 {
152 	if (dst) {
153 		WARN_ON(atomic_read(&dst->__refcnt) < 1);
154 		smp_mb__before_atomic_dec();
155 		atomic_dec(&dst->__refcnt);
156 	}
157 }
158 
159 /* Children define the path of the packet through the
160  * Linux networking.  Thus, destinations are stackable.
161  */
162 
163 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
164 {
165 	struct dst_entry *child = dst_clone(dst->child);
166 
167 	dst_release(dst);
168 	return child;
169 }
170 
171 extern void * dst_alloc(struct dst_ops * ops);
172 extern void __dst_free(struct dst_entry * dst);
173 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
174 
175 static inline void dst_free(struct dst_entry * dst)
176 {
177 	if (dst->obsolete > 1)
178 		return;
179 	if (!atomic_read(&dst->__refcnt)) {
180 		dst = dst_destroy(dst);
181 		if (!dst)
182 			return;
183 	}
184 	__dst_free(dst);
185 }
186 
187 static inline void dst_rcu_free(struct rcu_head *head)
188 {
189 	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
190 	dst_free(dst);
191 }
192 
193 static inline void dst_confirm(struct dst_entry *dst)
194 {
195 	if (dst)
196 		neigh_confirm(dst->neighbour);
197 }
198 
199 static inline void dst_negative_advice(struct dst_entry **dst_p)
200 {
201 	struct dst_entry * dst = *dst_p;
202 	if (dst && dst->ops->negative_advice)
203 		*dst_p = dst->ops->negative_advice(dst);
204 }
205 
206 static inline void dst_link_failure(struct sk_buff *skb)
207 {
208 	struct dst_entry * dst = skb->dst;
209 	if (dst && dst->ops && dst->ops->link_failure)
210 		dst->ops->link_failure(skb);
211 }
212 
213 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
214 {
215 	unsigned long expires = jiffies + timeout;
216 
217 	if (expires == 0)
218 		expires = 1;
219 
220 	if (dst->expires == 0 || time_before(expires, dst->expires))
221 		dst->expires = expires;
222 }
223 
224 /* Output packet to network from transport.  */
225 static inline int dst_output(struct sk_buff *skb)
226 {
227 	int err;
228 
229 	for (;;) {
230 		err = skb->dst->output(skb);
231 
232 		if (likely(err == 0))
233 			return err;
234 		if (unlikely(err != NET_XMIT_BYPASS))
235 			return err;
236 	}
237 }
238 
239 /* Input packet from network to transport.  */
240 static inline int dst_input(struct sk_buff *skb)
241 {
242 	int err;
243 
244 	for (;;) {
245 		err = skb->dst->input(skb);
246 
247 		if (likely(err == 0))
248 			return err;
249 		/* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
250 		if (unlikely(err != NET_XMIT_BYPASS))
251 			return err;
252 	}
253 }
254 
255 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
256 {
257 	if (dst->obsolete)
258 		dst = dst->ops->check(dst, cookie);
259 	return dst;
260 }
261 
262 extern void		dst_init(void);
263 
264 struct flowi;
265 #ifndef CONFIG_XFRM
266 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
267 		       struct sock *sk, int flags)
268 {
269 	return 0;
270 }
271 #else
272 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
273 		       struct sock *sk, int flags);
274 #endif
275 #endif
276 
277 #endif /* _NET_DST_H */
278