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Linux/include/net/dst.h

  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 dst_entry        *from;
 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 net *net, struct sock *sk, struct sk_buff *skb);
 49 
 50         unsigned short          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_FAKE_RTABLE         0x0040
 58 #define DST_XFRM_TUNNEL         0x0080
 59 #define DST_XFRM_QUEUE          0x0100
 60 #define DST_METADATA            0x0200
 61 
 62         unsigned short          pending_confirm;
 63 
 64         short                   error;
 65 
 66         /* A non-zero value of dst->obsolete forces by-hand validation
 67          * of the route entry.  Positive values are set by the generic
 68          * dst layer to indicate that the entry has been forcefully
 69          * destroyed.
 70          *
 71          * Negative values are used by the implementation layer code to
 72          * force invocation of the dst_ops->check() method.
 73          */
 74         short                   obsolete;
 75 #define DST_OBSOLETE_NONE       0
 76 #define DST_OBSOLETE_DEAD       2
 77 #define DST_OBSOLETE_FORCE_CHK  -1
 78 #define DST_OBSOLETE_KILL       -2
 79         unsigned short          header_len;     /* more space at head required */
 80         unsigned short          trailer_len;    /* space to reserve at tail */
 81 #ifdef CONFIG_IP_ROUTE_CLASSID
 82         __u32                   tclassid;
 83 #else
 84         __u32                   __pad2;
 85 #endif
 86 
 87 #ifdef CONFIG_64BIT
 88         /*
 89          * Align __refcnt to a 64 bytes alignment
 90          * (L1_CACHE_SIZE would be too much)
 91          */
 92         long                    __pad_to_align_refcnt[2];
 93 #endif
 94         /*
 95          * __refcnt wants to be on a different cache line from
 96          * input/output/ops or performance tanks badly
 97          */
 98         atomic_t                __refcnt;       /* client references    */
 99         int                     __use;
100         unsigned long           lastuse;
101         struct lwtunnel_state   *lwtstate;
102         union {
103                 struct dst_entry        *next;
104                 struct rtable __rcu     *rt_next;
105                 struct rt6_info         *rt6_next;
106                 struct dn_route __rcu   *dn_next;
107         };
108 };
109 
110 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
111 extern const u32 dst_default_metrics[];
112 
113 #define DST_METRICS_READ_ONLY           0x1UL
114 #define DST_METRICS_FLAGS               0x3UL
115 #define __DST_METRICS_PTR(Y)    \
116         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
117 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
118 
119 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
120 {
121         return dst->_metrics & DST_METRICS_READ_ONLY;
122 }
123 
124 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
125 
126 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
127 {
128         unsigned long val = dst->_metrics;
129         if (!(val & DST_METRICS_READ_ONLY))
130                 __dst_destroy_metrics_generic(dst, val);
131 }
132 
133 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
134 {
135         unsigned long p = dst->_metrics;
136 
137         BUG_ON(!p);
138 
139         if (p & DST_METRICS_READ_ONLY)
140                 return dst->ops->cow_metrics(dst, p);
141         return __DST_METRICS_PTR(p);
142 }
143 
144 /* This may only be invoked before the entry has reached global
145  * visibility.
146  */
147 static inline void dst_init_metrics(struct dst_entry *dst,
148                                     const u32 *src_metrics,
149                                     bool read_only)
150 {
151         dst->_metrics = ((unsigned long) src_metrics) |
152                 (read_only ? DST_METRICS_READ_ONLY : 0);
153 }
154 
155 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
156 {
157         u32 *dst_metrics = dst_metrics_write_ptr(dest);
158 
159         if (dst_metrics) {
160                 u32 *src_metrics = DST_METRICS_PTR(src);
161 
162                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
163         }
164 }
165 
166 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
167 {
168         return DST_METRICS_PTR(dst);
169 }
170 
171 static inline u32
172 dst_metric_raw(const struct dst_entry *dst, const int metric)
173 {
174         u32 *p = DST_METRICS_PTR(dst);
175 
176         return p[metric-1];
177 }
178 
179 static inline u32
180 dst_metric(const struct dst_entry *dst, const int metric)
181 {
182         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
183                      metric == RTAX_ADVMSS ||
184                      metric == RTAX_MTU);
185         return dst_metric_raw(dst, metric);
186 }
187 
188 static inline u32
189 dst_metric_advmss(const struct dst_entry *dst)
190 {
191         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
192 
193         if (!advmss)
194                 advmss = dst->ops->default_advmss(dst);
195 
196         return advmss;
197 }
198 
199 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
200 {
201         u32 *p = dst_metrics_write_ptr(dst);
202 
203         if (p)
204                 p[metric-1] = val;
205 }
206 
207 /* Kernel-internal feature bits that are unallocated in user space. */
208 #define DST_FEATURE_ECN_CA      (1 << 31)
209 
210 #define DST_FEATURE_MASK        (DST_FEATURE_ECN_CA)
211 #define DST_FEATURE_ECN_MASK    (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
212 
213 static inline u32
214 dst_feature(const struct dst_entry *dst, u32 feature)
215 {
216         return dst_metric(dst, RTAX_FEATURES) & feature;
217 }
218 
219 static inline u32 dst_mtu(const struct dst_entry *dst)
220 {
221         return dst->ops->mtu(dst);
222 }
223 
224 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
225 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
226 {
227         return msecs_to_jiffies(dst_metric(dst, metric));
228 }
229 
230 static inline u32
231 dst_allfrag(const struct dst_entry *dst)
232 {
233         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
234         return ret;
235 }
236 
237 static inline int
238 dst_metric_locked(const struct dst_entry *dst, int metric)
239 {
240         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
241 }
242 
243 static inline void dst_hold(struct dst_entry *dst)
244 {
245         /*
246          * If your kernel compilation stops here, please check
247          * __pad_to_align_refcnt declaration in struct dst_entry
248          */
249         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
250         atomic_inc(&dst->__refcnt);
251 }
252 
253 static inline void dst_use(struct dst_entry *dst, unsigned long time)
254 {
255         dst_hold(dst);
256         dst->__use++;
257         dst->lastuse = time;
258 }
259 
260 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
261 {
262         dst->__use++;
263         dst->lastuse = time;
264 }
265 
266 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
267 {
268         if (dst)
269                 atomic_inc(&dst->__refcnt);
270         return dst;
271 }
272 
273 void dst_release(struct dst_entry *dst);
274 
275 static inline void refdst_drop(unsigned long refdst)
276 {
277         if (!(refdst & SKB_DST_NOREF))
278                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
279 }
280 
281 /**
282  * skb_dst_drop - drops skb dst
283  * @skb: buffer
284  *
285  * Drops dst reference count if a reference was taken.
286  */
287 static inline void skb_dst_drop(struct sk_buff *skb)
288 {
289         if (skb->_skb_refdst) {
290                 refdst_drop(skb->_skb_refdst);
291                 skb->_skb_refdst = 0UL;
292         }
293 }
294 
295 static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
296 {
297         nskb->_skb_refdst = refdst;
298         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
299                 dst_clone(skb_dst(nskb));
300 }
301 
302 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
303 {
304         __skb_dst_copy(nskb, oskb->_skb_refdst);
305 }
306 
307 /**
308  * skb_dst_force - makes sure skb dst is refcounted
309  * @skb: buffer
310  *
311  * If dst is not yet refcounted, let's do it
312  */
313 static inline void skb_dst_force(struct sk_buff *skb)
314 {
315         if (skb_dst_is_noref(skb)) {
316                 WARN_ON(!rcu_read_lock_held());
317                 skb->_skb_refdst &= ~SKB_DST_NOREF;
318                 dst_clone(skb_dst(skb));
319         }
320 }
321 
322 /**
323  * dst_hold_safe - Take a reference on a dst if possible
324  * @dst: pointer to dst entry
325  *
326  * This helper returns false if it could not safely
327  * take a reference on a dst.
328  */
329 static inline bool dst_hold_safe(struct dst_entry *dst)
330 {
331         if (dst->flags & DST_NOCACHE)
332                 return atomic_inc_not_zero(&dst->__refcnt);
333         dst_hold(dst);
334         return true;
335 }
336 
337 /**
338  * skb_dst_force_safe - makes sure skb dst is refcounted
339  * @skb: buffer
340  *
341  * If dst is not yet refcounted and not destroyed, grab a ref on it.
342  */
343 static inline void skb_dst_force_safe(struct sk_buff *skb)
344 {
345         if (skb_dst_is_noref(skb)) {
346                 struct dst_entry *dst = skb_dst(skb);
347 
348                 if (!dst_hold_safe(dst))
349                         dst = NULL;
350 
351                 skb->_skb_refdst = (unsigned long)dst;
352         }
353 }
354 
355 
356 /**
357  *      __skb_tunnel_rx - prepare skb for rx reinsert
358  *      @skb: buffer
359  *      @dev: tunnel device
360  *      @net: netns for packet i/o
361  *
362  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
363  *      so make some cleanups. (no accounting done)
364  */
365 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
366                                    struct net *net)
367 {
368         skb->dev = dev;
369 
370         /*
371          * Clear hash so that we can recalulate the hash for the
372          * encapsulated packet, unless we have already determine the hash
373          * over the L4 4-tuple.
374          */
375         skb_clear_hash_if_not_l4(skb);
376         skb_set_queue_mapping(skb, 0);
377         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
378 }
379 
380 /**
381  *      skb_tunnel_rx - prepare skb for rx reinsert
382  *      @skb: buffer
383  *      @dev: tunnel device
384  *
385  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
386  *      so make some cleanups, and perform accounting.
387  *      Note: this accounting is not SMP safe.
388  */
389 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
390                                  struct net *net)
391 {
392         /* TODO : stats should be SMP safe */
393         dev->stats.rx_packets++;
394         dev->stats.rx_bytes += skb->len;
395         __skb_tunnel_rx(skb, dev, net);
396 }
397 
398 static inline u32 dst_tclassid(const struct sk_buff *skb)
399 {
400 #ifdef CONFIG_IP_ROUTE_CLASSID
401         const struct dst_entry *dst;
402 
403         dst = skb_dst(skb);
404         if (dst)
405                 return dst->tclassid;
406 #endif
407         return 0;
408 }
409 
410 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
411 static inline int dst_discard(struct sk_buff *skb)
412 {
413         return dst_discard_out(&init_net, skb->sk, skb);
414 }
415 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
416                 int initial_obsolete, unsigned short flags);
417 void dst_init(struct dst_entry *dst, struct dst_ops *ops,
418               struct net_device *dev, int initial_ref, int initial_obsolete,
419               unsigned short flags);
420 void __dst_free(struct dst_entry *dst);
421 struct dst_entry *dst_destroy(struct dst_entry *dst);
422 
423 static inline void dst_free(struct dst_entry *dst)
424 {
425         if (dst->obsolete > 0)
426                 return;
427         if (!atomic_read(&dst->__refcnt)) {
428                 dst = dst_destroy(dst);
429                 if (!dst)
430                         return;
431         }
432         __dst_free(dst);
433 }
434 
435 static inline void dst_rcu_free(struct rcu_head *head)
436 {
437         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
438         dst_free(dst);
439 }
440 
441 static inline void dst_confirm(struct dst_entry *dst)
442 {
443         dst->pending_confirm = 1;
444 }
445 
446 static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
447                                    struct sk_buff *skb)
448 {
449         const struct hh_cache *hh;
450 
451         if (dst->pending_confirm) {
452                 unsigned long now = jiffies;
453 
454                 dst->pending_confirm = 0;
455                 /* avoid dirtying neighbour */
456                 if (n->confirmed != now)
457                         n->confirmed = now;
458         }
459 
460         hh = &n->hh;
461         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
462                 return neigh_hh_output(hh, skb);
463         else
464                 return n->output(n, skb);
465 }
466 
467 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
468 {
469         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
470         return IS_ERR(n) ? NULL : n;
471 }
472 
473 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
474                                                      struct sk_buff *skb)
475 {
476         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
477         return IS_ERR(n) ? NULL : n;
478 }
479 
480 static inline void dst_link_failure(struct sk_buff *skb)
481 {
482         struct dst_entry *dst = skb_dst(skb);
483         if (dst && dst->ops && dst->ops->link_failure)
484                 dst->ops->link_failure(skb);
485 }
486 
487 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
488 {
489         unsigned long expires = jiffies + timeout;
490 
491         if (expires == 0)
492                 expires = 1;
493 
494         if (dst->expires == 0 || time_before(expires, dst->expires))
495                 dst->expires = expires;
496 }
497 
498 /* Output packet to network from transport.  */
499 static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
500 {
501         return skb_dst(skb)->output(net, sk, skb);
502 }
503 
504 /* Input packet from network to transport.  */
505 static inline int dst_input(struct sk_buff *skb)
506 {
507         return skb_dst(skb)->input(skb);
508 }
509 
510 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
511 {
512         if (dst->obsolete)
513                 dst = dst->ops->check(dst, cookie);
514         return dst;
515 }
516 
517 void dst_subsys_init(void);
518 
519 /* Flags for xfrm_lookup flags argument. */
520 enum {
521         XFRM_LOOKUP_ICMP = 1 << 0,
522         XFRM_LOOKUP_QUEUE = 1 << 1,
523         XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
524 };
525 
526 struct flowi;
527 #ifndef CONFIG_XFRM
528 static inline struct dst_entry *xfrm_lookup(struct net *net,
529                                             struct dst_entry *dst_orig,
530                                             const struct flowi *fl,
531                                             const struct sock *sk,
532                                             int flags)
533 {
534         return dst_orig;
535 }
536 
537 static inline struct dst_entry *xfrm_lookup_route(struct net *net,
538                                                   struct dst_entry *dst_orig,
539                                                   const struct flowi *fl,
540                                                   const struct sock *sk,
541                                                   int flags)
542 {
543         return dst_orig;
544 }
545 
546 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
547 {
548         return NULL;
549 }
550 
551 #else
552 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
553                               const struct flowi *fl, const struct sock *sk,
554                               int flags);
555 
556 struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
557                                     const struct flowi *fl, const struct sock *sk,
558                                     int flags);
559 
560 /* skb attached with this dst needs transformation if dst->xfrm is valid */
561 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
562 {
563         return dst->xfrm;
564 }
565 #endif
566 
567 #endif /* _NET_DST_H */
568 

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