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
31struct sk_buff;
32
33struct 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	union {
40		unsigned long           expires;
41		/* point to where the dst_entry copied from */
42		struct dst_entry        *from;
43	};
44	struct dst_entry	*path;
45	struct neighbour __rcu	*_neighbour;
46#ifdef CONFIG_XFRM
47	struct xfrm_state	*xfrm;
48#else
49	void			*__pad1;
50#endif
51	int			(*input)(struct sk_buff*);
52	int			(*output)(struct sk_buff*);
53
54	int			flags;
55#define DST_HOST		0x0001
56#define DST_NOXFRM		0x0002
57#define DST_NOPOLICY		0x0004
58#define DST_NOHASH		0x0008
59#define DST_NOCACHE		0x0010
60#define DST_NOCOUNT		0x0020
61#define DST_NOPEER		0x0040
62#define DST_FAKE_RTABLE		0x0080
63#define DST_XFRM_TUNNEL		0x0100
64
65	short			error;
66	short			obsolete;
67	unsigned short		header_len;	/* more space at head required */
68	unsigned short		trailer_len;	/* space to reserve at tail */
69#ifdef CONFIG_IP_ROUTE_CLASSID
70	__u32			tclassid;
71#else
72	__u32			__pad2;
73#endif
74
75	/*
76	 * Align __refcnt to a 64 bytes alignment
77	 * (L1_CACHE_SIZE would be too much)
78	 */
79#ifdef CONFIG_64BIT
80	long			__pad_to_align_refcnt[2];
81#endif
82	/*
83	 * __refcnt wants to be on a different cache line from
84	 * input/output/ops or performance tanks badly
85	 */
86	atomic_t		__refcnt;	/* client references	*/
87	int			__use;
88	unsigned long		lastuse;
89	union {
90		struct dst_entry	*next;
91		struct rtable __rcu	*rt_next;
92		struct rt6_info		*rt6_next;
93		struct dn_route __rcu	*dn_next;
94	};
95};
96
97static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst)
98{
99	return rcu_dereference(dst->_neighbour);
100}
101
102static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst)
103{
104	return rcu_dereference_raw(dst->_neighbour);
105}
106
107static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
108{
109	rcu_assign_pointer(dst->_neighbour, neigh);
110}
111
112extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
113extern const u32 dst_default_metrics[RTAX_MAX];
114
115#define DST_METRICS_READ_ONLY	0x1UL
116#define __DST_METRICS_PTR(Y)	\
117	((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
118#define DST_METRICS_PTR(X)	__DST_METRICS_PTR((X)->_metrics)
119
120static inline bool dst_metrics_read_only(const struct dst_entry *dst)
121{
122	return dst->_metrics & DST_METRICS_READ_ONLY;
123}
124
125extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
126
127static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
128{
129	unsigned long val = dst->_metrics;
130	if (!(val & DST_METRICS_READ_ONLY))
131		__dst_destroy_metrics_generic(dst, val);
132}
133
134static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
135{
136	unsigned long p = dst->_metrics;
137
138	BUG_ON(!p);
139
140	if (p & DST_METRICS_READ_ONLY)
141		return dst->ops->cow_metrics(dst, p);
142	return __DST_METRICS_PTR(p);
143}
144
145/* This may only be invoked before the entry has reached global
146 * visibility.
147 */
148static inline void dst_init_metrics(struct dst_entry *dst,
149				    const u32 *src_metrics,
150				    bool read_only)
151{
152	dst->_metrics = ((unsigned long) src_metrics) |
153		(read_only ? DST_METRICS_READ_ONLY : 0);
154}
155
156static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
157{
158	u32 *dst_metrics = dst_metrics_write_ptr(dest);
159
160	if (dst_metrics) {
161		u32 *src_metrics = DST_METRICS_PTR(src);
162
163		memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
164	}
165}
166
167static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
168{
169	return DST_METRICS_PTR(dst);
170}
171
172static inline u32
173dst_metric_raw(const struct dst_entry *dst, const int metric)
174{
175	u32 *p = DST_METRICS_PTR(dst);
176
177	return p[metric-1];
178}
179
180static inline u32
181dst_metric(const struct dst_entry *dst, const int metric)
182{
183	WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
184		     metric == RTAX_ADVMSS ||
185		     metric == RTAX_MTU);
186	return dst_metric_raw(dst, metric);
187}
188
189static inline u32
190dst_metric_advmss(const struct dst_entry *dst)
191{
192	u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
193
194	if (!advmss)
195		advmss = dst->ops->default_advmss(dst);
196
197	return advmss;
198}
199
200static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
201{
202	u32 *p = dst_metrics_write_ptr(dst);
203
204	if (p)
205		p[metric-1] = val;
206}
207
208static inline u32
209dst_feature(const struct dst_entry *dst, u32 feature)
210{
211	return dst_metric(dst, RTAX_FEATURES) & feature;
212}
213
214static inline u32 dst_mtu(const struct dst_entry *dst)
215{
216	return dst->ops->mtu(dst);
217}
218
219/* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
220static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
221{
222	return msecs_to_jiffies(dst_metric(dst, metric));
223}
224
225static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
226				      unsigned long rtt)
227{
228	dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
229}
230
231static inline u32
232dst_allfrag(const struct dst_entry *dst)
233{
234	int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
235	return ret;
236}
237
238static inline int
239dst_metric_locked(const struct dst_entry *dst, int metric)
240{
241	return dst_metric(dst, RTAX_LOCK) & (1<<metric);
242}
243
244static inline void dst_hold(struct dst_entry * dst)
245{
246	/*
247	 * If your kernel compilation stops here, please check
248	 * __pad_to_align_refcnt declaration in struct dst_entry
249	 */
250	BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
251	atomic_inc(&dst->__refcnt);
252}
253
254static inline void dst_use(struct dst_entry *dst, unsigned long time)
255{
256	dst_hold(dst);
257	dst->__use++;
258	dst->lastuse = time;
259}
260
261static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
262{
263	dst->__use++;
264	dst->lastuse = time;
265}
266
267static inline
268struct dst_entry * dst_clone(struct dst_entry * dst)
269{
270	if (dst)
271		atomic_inc(&dst->__refcnt);
272	return dst;
273}
274
275extern void dst_release(struct dst_entry *dst);
276
277static inline void refdst_drop(unsigned long refdst)
278{
279	if (!(refdst & SKB_DST_NOREF))
280		dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
281}
282
283/**
284 * skb_dst_drop - drops skb dst
285 * @skb: buffer
286 *
287 * Drops dst reference count if a reference was taken.
288 */
289static inline void skb_dst_drop(struct sk_buff *skb)
290{
291	if (skb->_skb_refdst) {
292		refdst_drop(skb->_skb_refdst);
293		skb->_skb_refdst = 0UL;
294	}
295}
296
297static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
298{
299	nskb->_skb_refdst = oskb->_skb_refdst;
300	if (!(nskb->_skb_refdst & SKB_DST_NOREF))
301		dst_clone(skb_dst(nskb));
302}
303
304/**
305 * skb_dst_force - makes sure skb dst is refcounted
306 * @skb: buffer
307 *
308 * If dst is not yet refcounted, let's do it
309 */
310static inline void skb_dst_force(struct sk_buff *skb)
311{
312	if (skb_dst_is_noref(skb)) {
313		WARN_ON(!rcu_read_lock_held());
314		skb->_skb_refdst &= ~SKB_DST_NOREF;
315		dst_clone(skb_dst(skb));
316	}
317}
318
319
320/**
321 *	__skb_tunnel_rx - prepare skb for rx reinsert
322 *	@skb: buffer
323 *	@dev: tunnel device
324 *
325 *	After decapsulation, packet is going to re-enter (netif_rx()) our stack,
326 *	so make some cleanups. (no accounting done)
327 */
328static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
329{
330	skb->dev = dev;
331
332	/*
333	 * Clear rxhash so that we can recalulate the hash for the
334	 * encapsulated packet, unless we have already determine the hash
335	 * over the L4 4-tuple.
336	 */
337	if (!skb->l4_rxhash)
338		skb->rxhash = 0;
339	skb_set_queue_mapping(skb, 0);
340	skb_dst_drop(skb);
341	nf_reset(skb);
342}
343
344/**
345 *	skb_tunnel_rx - prepare skb for rx reinsert
346 *	@skb: buffer
347 *	@dev: tunnel device
348 *
349 *	After decapsulation, packet is going to re-enter (netif_rx()) our stack,
350 *	so make some cleanups, and perform accounting.
351 *	Note: this accounting is not SMP safe.
352 */
353static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
354{
355	/* TODO : stats should be SMP safe */
356	dev->stats.rx_packets++;
357	dev->stats.rx_bytes += skb->len;
358	__skb_tunnel_rx(skb, dev);
359}
360
361/* Children define the path of the packet through the
362 * Linux networking.  Thus, destinations are stackable.
363 */
364
365static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
366{
367	struct dst_entry *child = dst_clone(skb_dst(skb)->child);
368
369	skb_dst_drop(skb);
370	return child;
371}
372
373extern int dst_discard(struct sk_buff *skb);
374extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
375		       int initial_ref, int initial_obsolete, int flags);
376extern void __dst_free(struct dst_entry * dst);
377extern struct dst_entry *dst_destroy(struct dst_entry * dst);
378
379static inline void dst_free(struct dst_entry * dst)
380{
381	if (dst->obsolete > 1)
382		return;
383	if (!atomic_read(&dst->__refcnt)) {
384		dst = dst_destroy(dst);
385		if (!dst)
386			return;
387	}
388	__dst_free(dst);
389}
390
391static inline void dst_rcu_free(struct rcu_head *head)
392{
393	struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
394	dst_free(dst);
395}
396
397static inline void dst_confirm(struct dst_entry *dst)
398{
399	if (dst) {
400		struct neighbour *n;
401
402		rcu_read_lock();
403		n = dst_get_neighbour_noref(dst);
404		neigh_confirm(n);
405		rcu_read_unlock();
406	}
407}
408
409static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
410{
411	return dst->ops->neigh_lookup(dst, daddr);
412}
413
414static inline void dst_link_failure(struct sk_buff *skb)
415{
416	struct dst_entry *dst = skb_dst(skb);
417	if (dst && dst->ops && dst->ops->link_failure)
418		dst->ops->link_failure(skb);
419}
420
421static inline void dst_set_expires(struct dst_entry *dst, int timeout)
422{
423	unsigned long expires = jiffies + timeout;
424
425	if (expires == 0)
426		expires = 1;
427
428	if (dst->expires == 0 || time_before(expires, dst->expires))
429		dst->expires = expires;
430}
431
432/* Output packet to network from transport.  */
433static inline int dst_output(struct sk_buff *skb)
434{
435	return skb_dst(skb)->output(skb);
436}
437
438/* Input packet from network to transport.  */
439static inline int dst_input(struct sk_buff *skb)
440{
441	return skb_dst(skb)->input(skb);
442}
443
444static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
445{
446	if (dst->obsolete)
447		dst = dst->ops->check(dst, cookie);
448	return dst;
449}
450
451extern void		dst_init(void);
452
453/* Flags for xfrm_lookup flags argument. */
454enum {
455	XFRM_LOOKUP_ICMP = 1 << 0,
456};
457
458struct flowi;
459#ifndef CONFIG_XFRM
460static inline struct dst_entry *xfrm_lookup(struct net *net,
461					    struct dst_entry *dst_orig,
462					    const struct flowi *fl, struct sock *sk,
463					    int flags)
464{
465	return dst_orig;
466}
467#else
468extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
469				     const struct flowi *fl, struct sock *sk,
470				     int flags);
471#endif
472
473#endif /* _NET_DST_H */
474