xref: /openbmc/linux/include/net/dst.h (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/netdevice.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 rcu_head		rcu_head;
41 	struct dst_entry	*child;
42 	struct net_device       *dev;
43 	short			error;
44 	short			obsolete;
45 	int			flags;
46 #define DST_HOST		1
47 #define DST_NOXFRM		2
48 #define DST_NOPOLICY		4
49 #define DST_NOHASH		8
50 #define DST_BALANCED            0x10
51 	unsigned long		expires;
52 
53 	unsigned short		header_len;	/* more space at head required */
54 	unsigned short		nfheader_len;	/* more non-fragment space at head required */
55 	unsigned short		trailer_len;	/* space to reserve at tail */
56 
57 	u32			metrics[RTAX_MAX];
58 	struct dst_entry	*path;
59 
60 	unsigned long		rate_last;	/* rate limiting for ICMP */
61 	unsigned long		rate_tokens;
62 
63 	struct neighbour	*neighbour;
64 	struct hh_cache		*hh;
65 	struct xfrm_state	*xfrm;
66 
67 	int			(*input)(struct sk_buff*);
68 	int			(*output)(struct sk_buff*);
69 
70 #ifdef CONFIG_NET_CLS_ROUTE
71 	__u32			tclassid;
72 #endif
73 
74 	struct  dst_ops	        *ops;
75 
76 	unsigned long		lastuse;
77 	atomic_t		__refcnt;	/* client references	*/
78 	int			__use;
79 	union {
80 		struct dst_entry *next;
81 		struct rtable    *rt_next;
82 		struct rt6_info   *rt6_next;
83 		struct dn_route  *dn_next;
84 	};
85 	char			info[0];
86 };
87 
88 
89 struct dst_ops
90 {
91 	unsigned short		family;
92 	__be16			protocol;
93 	unsigned		gc_thresh;
94 
95 	int			(*gc)(void);
96 	struct dst_entry *	(*check)(struct dst_entry *, __u32 cookie);
97 	void			(*destroy)(struct dst_entry *);
98 	void			(*ifdown)(struct dst_entry *,
99 					  struct net_device *dev, int how);
100 	struct dst_entry *	(*negative_advice)(struct dst_entry *);
101 	void			(*link_failure)(struct sk_buff *);
102 	void			(*update_pmtu)(struct dst_entry *dst, u32 mtu);
103 	int			entry_size;
104 
105 	atomic_t		entries;
106 	struct kmem_cache 		*kmem_cachep;
107 };
108 
109 #ifdef __KERNEL__
110 
111 static inline u32
112 dst_metric(const struct dst_entry *dst, int metric)
113 {
114 	return dst->metrics[metric-1];
115 }
116 
117 static inline u32 dst_mtu(const struct dst_entry *dst)
118 {
119 	u32 mtu = dst_metric(dst, RTAX_MTU);
120 	/*
121 	 * Alexey put it here, so ask him about it :)
122 	 */
123 	barrier();
124 	return mtu;
125 }
126 
127 static inline u32
128 dst_allfrag(const struct dst_entry *dst)
129 {
130 	int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
131 	/* Yes, _exactly_. This is paranoia. */
132 	barrier();
133 	return ret;
134 }
135 
136 static inline int
137 dst_metric_locked(struct dst_entry *dst, int metric)
138 {
139 	return dst_metric(dst, RTAX_LOCK) & (1<<metric);
140 }
141 
142 static inline void dst_hold(struct dst_entry * dst)
143 {
144 	atomic_inc(&dst->__refcnt);
145 }
146 
147 static inline
148 struct dst_entry * dst_clone(struct dst_entry * dst)
149 {
150 	if (dst)
151 		atomic_inc(&dst->__refcnt);
152 	return dst;
153 }
154 
155 static inline
156 void dst_release(struct dst_entry * dst)
157 {
158 	if (dst) {
159 		WARN_ON(atomic_read(&dst->__refcnt) < 1);
160 		smp_mb__before_atomic_dec();
161 		atomic_dec(&dst->__refcnt);
162 	}
163 }
164 
165 /* Children define the path of the packet through the
166  * Linux networking.  Thus, destinations are stackable.
167  */
168 
169 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
170 {
171 	struct dst_entry *child = dst_clone(dst->child);
172 
173 	dst_release(dst);
174 	return child;
175 }
176 
177 extern void * dst_alloc(struct dst_ops * ops);
178 extern void __dst_free(struct dst_entry * dst);
179 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
180 
181 static inline void dst_free(struct dst_entry * dst)
182 {
183 	if (dst->obsolete > 1)
184 		return;
185 	if (!atomic_read(&dst->__refcnt)) {
186 		dst = dst_destroy(dst);
187 		if (!dst)
188 			return;
189 	}
190 	__dst_free(dst);
191 }
192 
193 static inline void dst_rcu_free(struct rcu_head *head)
194 {
195 	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
196 	dst_free(dst);
197 }
198 
199 static inline void dst_confirm(struct dst_entry *dst)
200 {
201 	if (dst)
202 		neigh_confirm(dst->neighbour);
203 }
204 
205 static inline void dst_negative_advice(struct dst_entry **dst_p)
206 {
207 	struct dst_entry * dst = *dst_p;
208 	if (dst && dst->ops->negative_advice)
209 		*dst_p = dst->ops->negative_advice(dst);
210 }
211 
212 static inline void dst_link_failure(struct sk_buff *skb)
213 {
214 	struct dst_entry * dst = skb->dst;
215 	if (dst && dst->ops && dst->ops->link_failure)
216 		dst->ops->link_failure(skb);
217 }
218 
219 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
220 {
221 	unsigned long expires = jiffies + timeout;
222 
223 	if (expires == 0)
224 		expires = 1;
225 
226 	if (dst->expires == 0 || time_before(expires, dst->expires))
227 		dst->expires = expires;
228 }
229 
230 /* Output packet to network from transport.  */
231 static inline int dst_output(struct sk_buff *skb)
232 {
233 	return skb->dst->output(skb);
234 }
235 
236 /* Input packet from network to transport.  */
237 static inline int dst_input(struct sk_buff *skb)
238 {
239 	int err;
240 
241 	for (;;) {
242 		err = skb->dst->input(skb);
243 
244 		if (likely(err == 0))
245 			return err;
246 		/* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
247 		if (unlikely(err != NET_XMIT_BYPASS))
248 			return err;
249 	}
250 }
251 
252 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
253 {
254 	if (dst->obsolete)
255 		dst = dst->ops->check(dst, cookie);
256 	return dst;
257 }
258 
259 extern void		dst_init(void);
260 
261 struct flowi;
262 #ifndef CONFIG_XFRM
263 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
264 		       struct sock *sk, int flags)
265 {
266 	return 0;
267 }
268 #else
269 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
270 		       struct sock *sk, int flags);
271 #endif
272 #endif
273 
274 #endif /* _NET_DST_H */
275