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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 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 
 61         unsigned short          pending_confirm;
 62 
 63         short                   error;
 64 
 65         /* A non-zero value of dst->obsolete forces by-hand validation
 66          * of the route entry.  Positive values are set by the generic
 67          * dst layer to indicate that the entry has been forcefully
 68          * destroyed.
 69          *
 70          * Negative values are used by the implementation layer code to
 71          * force invocation of the dst_ops->check() method.
 72          */
 73         short                   obsolete;
 74 #define DST_OBSOLETE_NONE       0
 75 #define DST_OBSOLETE_DEAD       2
 76 #define DST_OBSOLETE_FORCE_CHK  -1
 77 #define DST_OBSOLETE_KILL       -2
 78         unsigned short          header_len;     /* more space at head required */
 79         unsigned short          trailer_len;    /* space to reserve at tail */
 80 #ifdef CONFIG_IP_ROUTE_CLASSID
 81         __u32                   tclassid;
 82 #else
 83         __u32                   __pad2;
 84 #endif
 85 
 86         /*
 87          * Align __refcnt to a 64 bytes alignment
 88          * (L1_CACHE_SIZE would be too much)
 89          */
 90 #ifdef CONFIG_64BIT
 91         long                    __pad_to_align_refcnt[2];
 92 #endif
 93         /*
 94          * __refcnt wants to be on a different cache line from
 95          * input/output/ops or performance tanks badly
 96          */
 97         atomic_t                __refcnt;       /* client references    */
 98         int                     __use;
 99         unsigned long           lastuse;
100         union {
101                 struct dst_entry        *next;
102                 struct rtable __rcu     *rt_next;
103                 struct rt6_info         *rt6_next;
104                 struct dn_route __rcu   *dn_next;
105         };
106 };
107 
108 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
109 extern const u32 dst_default_metrics[];
110 
111 #define DST_METRICS_READ_ONLY           0x1UL
112 #define DST_METRICS_FORCE_OVERWRITE     0x2UL
113 #define DST_METRICS_FLAGS               0x3UL
114 #define __DST_METRICS_PTR(Y)    \
115         ((u32 *)((Y) & ~DST_METRICS_FLAGS))
116 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
117 
118 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
119 {
120         return dst->_metrics & DST_METRICS_READ_ONLY;
121 }
122 
123 static inline void dst_metrics_set_force_overwrite(struct dst_entry *dst)
124 {
125         dst->_metrics |= DST_METRICS_FORCE_OVERWRITE;
126 }
127 
128 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
129 
130 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
131 {
132         unsigned long val = dst->_metrics;
133         if (!(val & DST_METRICS_READ_ONLY))
134                 __dst_destroy_metrics_generic(dst, val);
135 }
136 
137 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
138 {
139         unsigned long p = dst->_metrics;
140 
141         BUG_ON(!p);
142 
143         if (p & DST_METRICS_READ_ONLY)
144                 return dst->ops->cow_metrics(dst, p);
145         return __DST_METRICS_PTR(p);
146 }
147 
148 /* This may only be invoked before the entry has reached global
149  * visibility.
150  */
151 static inline void dst_init_metrics(struct dst_entry *dst,
152                                     const u32 *src_metrics,
153                                     bool read_only)
154 {
155         dst->_metrics = ((unsigned long) src_metrics) |
156                 (read_only ? DST_METRICS_READ_ONLY : 0);
157 }
158 
159 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
160 {
161         u32 *dst_metrics = dst_metrics_write_ptr(dest);
162 
163         if (dst_metrics) {
164                 u32 *src_metrics = DST_METRICS_PTR(src);
165 
166                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
167         }
168 }
169 
170 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
171 {
172         return DST_METRICS_PTR(dst);
173 }
174 
175 static inline u32
176 dst_metric_raw(const struct dst_entry *dst, const int metric)
177 {
178         u32 *p = DST_METRICS_PTR(dst);
179 
180         return p[metric-1];
181 }
182 
183 static inline u32
184 dst_metric(const struct dst_entry *dst, const int metric)
185 {
186         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
187                      metric == RTAX_ADVMSS ||
188                      metric == RTAX_MTU);
189         return dst_metric_raw(dst, metric);
190 }
191 
192 static inline u32
193 dst_metric_advmss(const struct dst_entry *dst)
194 {
195         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
196 
197         if (!advmss)
198                 advmss = dst->ops->default_advmss(dst);
199 
200         return advmss;
201 }
202 
203 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
204 {
205         u32 *p = dst_metrics_write_ptr(dst);
206 
207         if (p)
208                 p[metric-1] = val;
209 }
210 
211 static inline u32
212 dst_feature(const struct dst_entry *dst, u32 feature)
213 {
214         return dst_metric(dst, RTAX_FEATURES) & feature;
215 }
216 
217 static inline u32 dst_mtu(const struct dst_entry *dst)
218 {
219         return dst->ops->mtu(dst);
220 }
221 
222 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
223 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
224 {
225         return msecs_to_jiffies(dst_metric(dst, metric));
226 }
227 
228 static inline u32
229 dst_allfrag(const struct dst_entry *dst)
230 {
231         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
232         return ret;
233 }
234 
235 static inline int
236 dst_metric_locked(const struct dst_entry *dst, int metric)
237 {
238         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
239 }
240 
241 static inline void dst_hold(struct dst_entry *dst)
242 {
243         /*
244          * If your kernel compilation stops here, please check
245          * __pad_to_align_refcnt declaration in struct dst_entry
246          */
247         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
248         atomic_inc(&dst->__refcnt);
249 }
250 
251 static inline void dst_use(struct dst_entry *dst, unsigned long time)
252 {
253         dst_hold(dst);
254         dst->__use++;
255         dst->lastuse = time;
256 }
257 
258 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
259 {
260         dst->__use++;
261         dst->lastuse = time;
262 }
263 
264 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
265 {
266         if (dst)
267                 atomic_inc(&dst->__refcnt);
268         return dst;
269 }
270 
271 void dst_release(struct dst_entry *dst);
272 
273 static inline void refdst_drop(unsigned long refdst)
274 {
275         if (!(refdst & SKB_DST_NOREF))
276                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
277 }
278 
279 /**
280  * skb_dst_drop - drops skb dst
281  * @skb: buffer
282  *
283  * Drops dst reference count if a reference was taken.
284  */
285 static inline void skb_dst_drop(struct sk_buff *skb)
286 {
287         if (skb->_skb_refdst) {
288                 refdst_drop(skb->_skb_refdst);
289                 skb->_skb_refdst = 0UL;
290         }
291 }
292 
293 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
294 {
295         nskb->_skb_refdst = oskb->_skb_refdst;
296         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
297                 dst_clone(skb_dst(nskb));
298 }
299 
300 /**
301  * skb_dst_force - makes sure skb dst is refcounted
302  * @skb: buffer
303  *
304  * If dst is not yet refcounted, let's do it
305  */
306 static inline void skb_dst_force(struct sk_buff *skb)
307 {
308         if (skb_dst_is_noref(skb)) {
309                 WARN_ON(!rcu_read_lock_held());
310                 skb->_skb_refdst &= ~SKB_DST_NOREF;
311                 dst_clone(skb_dst(skb));
312         }
313 }
314 
315 
316 /**
317  *      __skb_tunnel_rx - prepare skb for rx reinsert
318  *      @skb: buffer
319  *      @dev: tunnel device
320  *      @net: netns for packet i/o
321  *
322  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
323  *      so make some cleanups. (no accounting done)
324  */
325 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
326                                    struct net *net)
327 {
328         skb->dev = dev;
329 
330         /*
331          * Clear hash so that we can recalulate the hash for the
332          * encapsulated packet, unless we have already determine the hash
333          * over the L4 4-tuple.
334          */
335         skb_clear_hash_if_not_l4(skb);
336         skb_set_queue_mapping(skb, 0);
337         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
338 }
339 
340 /**
341  *      skb_tunnel_rx - prepare skb for rx reinsert
342  *      @skb: buffer
343  *      @dev: tunnel device
344  *
345  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
346  *      so make some cleanups, and perform accounting.
347  *      Note: this accounting is not SMP safe.
348  */
349 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
350                                  struct net *net)
351 {
352         /* TODO : stats should be SMP safe */
353         dev->stats.rx_packets++;
354         dev->stats.rx_bytes += skb->len;
355         __skb_tunnel_rx(skb, dev, net);
356 }
357 
358 /* Children define the path of the packet through the
359  * Linux networking.  Thus, destinations are stackable.
360  */
361 
362 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
363 {
364         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
365 
366         skb_dst_drop(skb);
367         return child;
368 }
369 
370 int dst_discard_sk(struct sock *sk, struct sk_buff *skb);
371 static inline int dst_discard(struct sk_buff *skb)
372 {
373         return dst_discard_sk(skb->sk, skb);
374 }
375 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
376                 int initial_obsolete, unsigned short flags);
377 void __dst_free(struct dst_entry *dst);
378 struct dst_entry *dst_destroy(struct dst_entry *dst);
379 
380 static inline void dst_free(struct dst_entry *dst)
381 {
382         if (dst->obsolete > 0)
383                 return;
384         if (!atomic_read(&dst->__refcnt)) {
385                 dst = dst_destroy(dst);
386                 if (!dst)
387                         return;
388         }
389         __dst_free(dst);
390 }
391 
392 static inline void dst_rcu_free(struct rcu_head *head)
393 {
394         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
395         dst_free(dst);
396 }
397 
398 static inline void dst_confirm(struct dst_entry *dst)
399 {
400         dst->pending_confirm = 1;
401 }
402 
403 static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
404                                    struct sk_buff *skb)
405 {
406         const struct hh_cache *hh;
407 
408         if (dst->pending_confirm) {
409                 unsigned long now = jiffies;
410 
411                 dst->pending_confirm = 0;
412                 /* avoid dirtying neighbour */
413                 if (n->confirmed != now)
414                         n->confirmed = now;
415         }
416 
417         hh = &n->hh;
418         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
419                 return neigh_hh_output(hh, skb);
420         else
421                 return n->output(n, skb);
422 }
423 
424 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
425 {
426         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
427         return IS_ERR(n) ? NULL : n;
428 }
429 
430 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
431                                                      struct sk_buff *skb)
432 {
433         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
434         return IS_ERR(n) ? NULL : n;
435 }
436 
437 static inline void dst_link_failure(struct sk_buff *skb)
438 {
439         struct dst_entry *dst = skb_dst(skb);
440         if (dst && dst->ops && dst->ops->link_failure)
441                 dst->ops->link_failure(skb);
442 }
443 
444 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
445 {
446         unsigned long expires = jiffies + timeout;
447 
448         if (expires == 0)
449                 expires = 1;
450 
451         if (dst->expires == 0 || time_before(expires, dst->expires))
452                 dst->expires = expires;
453 }
454 
455 /* Output packet to network from transport.  */
456 static inline int dst_output_sk(struct sock *sk, struct sk_buff *skb)
457 {
458         return skb_dst(skb)->output(sk, skb);
459 }
460 static inline int dst_output(struct sk_buff *skb)
461 {
462         return dst_output_sk(skb->sk, skb);
463 }
464 
465 /* Input packet from network to transport.  */
466 static inline int dst_input(struct sk_buff *skb)
467 {
468         return skb_dst(skb)->input(skb);
469 }
470 
471 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
472 {
473         if (dst->obsolete)
474                 dst = dst->ops->check(dst, cookie);
475         return dst;
476 }
477 
478 void dst_init(void);
479 
480 /* Flags for xfrm_lookup flags argument. */
481 enum {
482         XFRM_LOOKUP_ICMP = 1 << 0,
483 };
484 
485 struct flowi;
486 #ifndef CONFIG_XFRM
487 static inline struct dst_entry *xfrm_lookup(struct net *net,
488                                             struct dst_entry *dst_orig,
489                                             const struct flowi *fl, struct sock *sk,
490                                             int flags)
491 {
492         return dst_orig;
493 } 
494 
495 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
496 {
497         return NULL;
498 }
499 
500 #else
501 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
502                               const struct flowi *fl, struct sock *sk,
503                               int flags);
504 
505 /* skb attached with this dst needs transformation if dst->xfrm is valid */
506 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
507 {
508         return dst->xfrm;
509 }
510 #endif
511 
512 #endif /* _NET_DST_H */
513 

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