xref: /linux/include/net/dst.h (revision 87c34ed3aba9249cb06d1a1f100cd3618f29268c) 
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 <net/dst_ops.h>
12 #include <linux/netdevice.h>
13 #include <linux/rtnetlink.h>
14 #include <linux/rcupdate.h>
15 #include <linux/bug.h>
16 #include <linux/jiffies.h>
17 #include <net/neighbour.h>
18 #include <asm/processor.h>
19 
20 #define DST_GC_MIN	(HZ/10)
21 #define DST_GC_INC	(HZ/2)
22 #define DST_GC_MAX	(120*HZ)
23 
24 /* Each dst_entry has reference count and sits in some parent list(s).
25  * When it is removed from parent list, it is "freed" (dst_free).
26  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
27  * is zero, it can be destroyed immediately, otherwise it is added
28  * to gc list and garbage collector periodically checks the refcnt.
29  */
30 
31 struct sk_buff;
32 
33 struct dst_entry {
34 	struct rcu_head		rcu_head;
35 	struct dst_entry	*child;
36 	struct net_device       *dev;
37 	struct  dst_ops	        *ops;
38 	unsigned long		_metrics;
39 	unsigned long		expires;
40 	struct dst_entry	*path;
41 	struct neighbour __rcu	*_neighbour;
42 #ifdef CONFIG_XFRM
43 	struct xfrm_state	*xfrm;
44 #else
45 	void			*__pad1;
46 #endif
47 	int			(*input)(struct sk_buff*);
48 	int			(*output)(struct sk_buff*);
49 
50 	int			flags;
51 #define DST_HOST		0x0001
52 #define DST_NOXFRM		0x0002
53 #define DST_NOPOLICY		0x0004
54 #define DST_NOHASH		0x0008
55 #define DST_NOCACHE		0x0010
56 #define DST_NOCOUNT		0x0020
57 #define DST_NOPEER		0x0040
58 
59 	short			error;
60 	short			obsolete;
61 	unsigned short		header_len;	/* more space at head required */
62 	unsigned short		trailer_len;	/* space to reserve at tail */
63 #ifdef CONFIG_IP_ROUTE_CLASSID
64 	__u32			tclassid;
65 #else
66 	__u32			__pad2;
67 #endif
68 
69 	/*
70 	 * Align __refcnt to a 64 bytes alignment
71 	 * (L1_CACHE_SIZE would be too much)
72 	 */
73 #ifdef CONFIG_64BIT
74 	long			__pad_to_align_refcnt[2];
75 #endif
76 	/*
77 	 * __refcnt wants to be on a different cache line from
78 	 * input/output/ops or performance tanks badly
79 	 */
80 	atomic_t		__refcnt;	/* client references	*/
81 	int			__use;
82 	unsigned long		lastuse;
83 	union {
84 		struct dst_entry	*next;
85 		struct rtable __rcu	*rt_next;
86 		struct rt6_info		*rt6_next;
87 		struct dn_route __rcu	*dn_next;
88 	};
89 };
90 
91 static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst)
92 {
93 	return rcu_dereference(dst->_neighbour);
94 }
95 
96 static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst)
97 {
98 	return rcu_dereference_raw(dst->_neighbour);
99 }
100 
101 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
102 {
103 	rcu_assign_pointer(dst->_neighbour, neigh);
104 }
105 
106 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
107 extern const u32 dst_default_metrics[RTAX_MAX];
108 
109 #define DST_METRICS_READ_ONLY	0x1UL
110 #define __DST_METRICS_PTR(Y)	\
111 	((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
112 #define DST_METRICS_PTR(X)	__DST_METRICS_PTR((X)->_metrics)
113 
114 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
115 {
116 	return dst->_metrics & DST_METRICS_READ_ONLY;
117 }
118 
119 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
120 
121 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
122 {
123 	unsigned long val = dst->_metrics;
124 	if (!(val & DST_METRICS_READ_ONLY))
125 		__dst_destroy_metrics_generic(dst, val);
126 }
127 
128 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
129 {
130 	unsigned long p = dst->_metrics;
131 
132 	BUG_ON(!p);
133 
134 	if (p & DST_METRICS_READ_ONLY)
135 		return dst->ops->cow_metrics(dst, p);
136 	return __DST_METRICS_PTR(p);
137 }
138 
139 /* This may only be invoked before the entry has reached global
140  * visibility.
141  */
142 static inline void dst_init_metrics(struct dst_entry *dst,
143 				    const u32 *src_metrics,
144 				    bool read_only)
145 {
146 	dst->_metrics = ((unsigned long) src_metrics) |
147 		(read_only ? DST_METRICS_READ_ONLY : 0);
148 }
149 
150 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
151 {
152 	u32 *dst_metrics = dst_metrics_write_ptr(dest);
153 
154 	if (dst_metrics) {
155 		u32 *src_metrics = DST_METRICS_PTR(src);
156 
157 		memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
158 	}
159 }
160 
161 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
162 {
163 	return DST_METRICS_PTR(dst);
164 }
165 
166 static inline u32
167 dst_metric_raw(const struct dst_entry *dst, const int metric)
168 {
169 	u32 *p = DST_METRICS_PTR(dst);
170 
171 	return p[metric-1];
172 }
173 
174 static inline u32
175 dst_metric(const struct dst_entry *dst, const int metric)
176 {
177 	WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
178 		     metric == RTAX_ADVMSS ||
179 		     metric == RTAX_MTU);
180 	return dst_metric_raw(dst, metric);
181 }
182 
183 static inline u32
184 dst_metric_advmss(const struct dst_entry *dst)
185 {
186 	u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
187 
188 	if (!advmss)
189 		advmss = dst->ops->default_advmss(dst);
190 
191 	return advmss;
192 }
193 
194 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
195 {
196 	u32 *p = dst_metrics_write_ptr(dst);
197 
198 	if (p)
199 		p[metric-1] = val;
200 }
201 
202 static inline u32
203 dst_feature(const struct dst_entry *dst, u32 feature)
204 {
205 	return dst_metric(dst, RTAX_FEATURES) & feature;
206 }
207 
208 static inline u32 dst_mtu(const struct dst_entry *dst)
209 {
210 	return dst->ops->mtu(dst);
211 }
212 
213 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
214 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
215 {
216 	return msecs_to_jiffies(dst_metric(dst, metric));
217 }
218 
219 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
220 				      unsigned long rtt)
221 {
222 	dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
223 }
224 
225 static inline u32
226 dst_allfrag(const struct dst_entry *dst)
227 {
228 	int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
229 	return ret;
230 }
231 
232 static inline int
233 dst_metric_locked(const struct dst_entry *dst, int metric)
234 {
235 	return dst_metric(dst, RTAX_LOCK) & (1<<metric);
236 }
237 
238 static inline void dst_hold(struct dst_entry * dst)
239 {
240 	/*
241 	 * If your kernel compilation stops here, please check
242 	 * __pad_to_align_refcnt declaration in struct dst_entry
243 	 */
244 	BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
245 	atomic_inc(&dst->__refcnt);
246 }
247 
248 static inline void dst_use(struct dst_entry *dst, unsigned long time)
249 {
250 	dst_hold(dst);
251 	dst->__use++;
252 	dst->lastuse = time;
253 }
254 
255 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
256 {
257 	dst->__use++;
258 	dst->lastuse = time;
259 }
260 
261 static inline
262 struct dst_entry * dst_clone(struct dst_entry * dst)
263 {
264 	if (dst)
265 		atomic_inc(&dst->__refcnt);
266 	return dst;
267 }
268 
269 extern void dst_release(struct dst_entry *dst);
270 
271 static inline void refdst_drop(unsigned long refdst)
272 {
273 	if (!(refdst & SKB_DST_NOREF))
274 		dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
275 }
276 
277 /**
278  * skb_dst_drop - drops skb dst
279  * @skb: buffer
280  *
281  * Drops dst reference count if a reference was taken.
282  */
283 static inline void skb_dst_drop(struct sk_buff *skb)
284 {
285 	if (skb->_skb_refdst) {
286 		refdst_drop(skb->_skb_refdst);
287 		skb->_skb_refdst = 0UL;
288 	}
289 }
290 
291 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
292 {
293 	nskb->_skb_refdst = oskb->_skb_refdst;
294 	if (!(nskb->_skb_refdst & SKB_DST_NOREF))
295 		dst_clone(skb_dst(nskb));
296 }
297 
298 /**
299  * skb_dst_force - makes sure skb dst is refcounted
300  * @skb: buffer
301  *
302  * If dst is not yet refcounted, let's do it
303  */
304 static inline void skb_dst_force(struct sk_buff *skb)
305 {
306 	if (skb_dst_is_noref(skb)) {
307 		WARN_ON(!rcu_read_lock_held());
308 		skb->_skb_refdst &= ~SKB_DST_NOREF;
309 		dst_clone(skb_dst(skb));
310 	}
311 }
312 
313 
314 /**
315  *	__skb_tunnel_rx - prepare skb for rx reinsert
316  *	@skb: buffer
317  *	@dev: tunnel device
318  *
319  *	After decapsulation, packet is going to re-enter (netif_rx()) our stack,
320  *	so make some cleanups. (no accounting done)
321  */
322 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
323 {
324 	skb->dev = dev;
325 
326 	/*
327 	 * Clear rxhash so that we can recalulate the hash for the
328 	 * encapsulated packet, unless we have already determine the hash
329 	 * over the L4 4-tuple.
330 	 */
331 	if (!skb->l4_rxhash)
332 		skb->rxhash = 0;
333 	skb_set_queue_mapping(skb, 0);
334 	skb_dst_drop(skb);
335 	nf_reset(skb);
336 }
337 
338 /**
339  *	skb_tunnel_rx - prepare skb for rx reinsert
340  *	@skb: buffer
341  *	@dev: tunnel device
342  *
343  *	After decapsulation, packet is going to re-enter (netif_rx()) our stack,
344  *	so make some cleanups, and perform accounting.
345  *	Note: this accounting is not SMP safe.
346  */
347 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
348 {
349 	/* TODO : stats should be SMP safe */
350 	dev->stats.rx_packets++;
351 	dev->stats.rx_bytes += skb->len;
352 	__skb_tunnel_rx(skb, dev);
353 }
354 
355 /* Children define the path of the packet through the
356  * Linux networking.  Thus, destinations are stackable.
357  */
358 
359 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
360 {
361 	struct dst_entry *child = dst_clone(skb_dst(skb)->child);
362 
363 	skb_dst_drop(skb);
364 	return child;
365 }
366 
367 extern int dst_discard(struct sk_buff *skb);
368 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
369 		       int initial_ref, int initial_obsolete, int flags);
370 extern void __dst_free(struct dst_entry * dst);
371 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
372 
373 static inline void dst_free(struct dst_entry * dst)
374 {
375 	if (dst->obsolete > 1)
376 		return;
377 	if (!atomic_read(&dst->__refcnt)) {
378 		dst = dst_destroy(dst);
379 		if (!dst)
380 			return;
381 	}
382 	__dst_free(dst);
383 }
384 
385 static inline void dst_rcu_free(struct rcu_head *head)
386 {
387 	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
388 	dst_free(dst);
389 }
390 
391 static inline void dst_confirm(struct dst_entry *dst)
392 {
393 	if (dst) {
394 		struct neighbour *n;
395 
396 		rcu_read_lock();
397 		n = dst_get_neighbour_noref(dst);
398 		neigh_confirm(n);
399 		rcu_read_unlock();
400 	}
401 }
402 
403 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
404 {
405 	return dst->ops->neigh_lookup(dst, daddr);
406 }
407 
408 static inline void dst_link_failure(struct sk_buff *skb)
409 {
410 	struct dst_entry *dst = skb_dst(skb);
411 	if (dst && dst->ops && dst->ops->link_failure)
412 		dst->ops->link_failure(skb);
413 }
414 
415 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
416 {
417 	unsigned long expires = jiffies + timeout;
418 
419 	if (expires == 0)
420 		expires = 1;
421 
422 	if (dst->expires == 0 || time_before(expires, dst->expires))
423 		dst->expires = expires;
424 }
425 
426 /* Output packet to network from transport.  */
427 static inline int dst_output(struct sk_buff *skb)
428 {
429 	return skb_dst(skb)->output(skb);
430 }
431 
432 /* Input packet from network to transport.  */
433 static inline int dst_input(struct sk_buff *skb)
434 {
435 	return skb_dst(skb)->input(skb);
436 }
437 
438 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
439 {
440 	if (dst->obsolete)
441 		dst = dst->ops->check(dst, cookie);
442 	return dst;
443 }
444 
445 extern void		dst_init(void);
446 
447 /* Flags for xfrm_lookup flags argument. */
448 enum {
449 	XFRM_LOOKUP_ICMP = 1 << 0,
450 };
451 
452 struct flowi;
453 #ifndef CONFIG_XFRM
454 static inline struct dst_entry *xfrm_lookup(struct net *net,
455 					    struct dst_entry *dst_orig,
456 					    const struct flowi *fl, struct sock *sk,
457 					    int flags)
458 {
459 	return dst_orig;
460 }
461 #else
462 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
463 				     const struct flowi *fl, struct sock *sk,
464 				     int flags);
465 #endif
466 
467 #endif /* _NET_DST_H */
468