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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 sk_buff *);
 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_NOPEER              0x0040
 58 #define DST_FAKE_RTABLE         0x0080
 59 #define DST_XFRM_TUNNEL         0x0100
 60 #define DST_XFRM_QUEUE          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         /*
 88          * Align __refcnt to a 64 bytes alignment
 89          * (L1_CACHE_SIZE would be too much)
 90          */
 91 #ifdef CONFIG_64BIT
 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         union {
102                 struct dst_entry        *next;
103                 struct rtable __rcu     *rt_next;
104                 struct rt6_info         *rt6_next;
105                 struct dn_route __rcu   *dn_next;
106         };
107 };
108 
109 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
110 extern const u32 dst_default_metrics[];
111 
112 #define DST_METRICS_READ_ONLY   0x1UL
113 #define __DST_METRICS_PTR(Y)    \
114         ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
115 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
116 
117 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
118 {
119         return dst->_metrics & DST_METRICS_READ_ONLY;
120 }
121 
122 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
123 
124 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
125 {
126         unsigned long val = dst->_metrics;
127         if (!(val & DST_METRICS_READ_ONLY))
128                 __dst_destroy_metrics_generic(dst, val);
129 }
130 
131 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
132 {
133         unsigned long p = dst->_metrics;
134 
135         BUG_ON(!p);
136 
137         if (p & DST_METRICS_READ_ONLY)
138                 return dst->ops->cow_metrics(dst, p);
139         return __DST_METRICS_PTR(p);
140 }
141 
142 /* This may only be invoked before the entry has reached global
143  * visibility.
144  */
145 static inline void dst_init_metrics(struct dst_entry *dst,
146                                     const u32 *src_metrics,
147                                     bool read_only)
148 {
149         dst->_metrics = ((unsigned long) src_metrics) |
150                 (read_only ? DST_METRICS_READ_ONLY : 0);
151 }
152 
153 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
154 {
155         u32 *dst_metrics = dst_metrics_write_ptr(dest);
156 
157         if (dst_metrics) {
158                 u32 *src_metrics = DST_METRICS_PTR(src);
159 
160                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
161         }
162 }
163 
164 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
165 {
166         return DST_METRICS_PTR(dst);
167 }
168 
169 static inline u32
170 dst_metric_raw(const struct dst_entry *dst, const int metric)
171 {
172         u32 *p = DST_METRICS_PTR(dst);
173 
174         return p[metric-1];
175 }
176 
177 static inline u32
178 dst_metric(const struct dst_entry *dst, const int metric)
179 {
180         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
181                      metric == RTAX_ADVMSS ||
182                      metric == RTAX_MTU);
183         return dst_metric_raw(dst, metric);
184 }
185 
186 static inline u32
187 dst_metric_advmss(const struct dst_entry *dst)
188 {
189         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
190 
191         if (!advmss)
192                 advmss = dst->ops->default_advmss(dst);
193 
194         return advmss;
195 }
196 
197 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
198 {
199         u32 *p = dst_metrics_write_ptr(dst);
200 
201         if (p)
202                 p[metric-1] = val;
203 }
204 
205 static inline u32
206 dst_feature(const struct dst_entry *dst, u32 feature)
207 {
208         return dst_metric(dst, RTAX_FEATURES) & feature;
209 }
210 
211 static inline u32 dst_mtu(const struct dst_entry *dst)
212 {
213         return dst->ops->mtu(dst);
214 }
215 
216 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
217 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
218 {
219         return msecs_to_jiffies(dst_metric(dst, metric));
220 }
221 
222 static inline u32
223 dst_allfrag(const struct dst_entry *dst)
224 {
225         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
226         return ret;
227 }
228 
229 static inline int
230 dst_metric_locked(const struct dst_entry *dst, int metric)
231 {
232         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
233 }
234 
235 static inline void dst_hold(struct dst_entry *dst)
236 {
237         /*
238          * If your kernel compilation stops here, please check
239          * __pad_to_align_refcnt declaration in struct dst_entry
240          */
241         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
242         atomic_inc(&dst->__refcnt);
243 }
244 
245 static inline void dst_use(struct dst_entry *dst, unsigned long time)
246 {
247         dst_hold(dst);
248         dst->__use++;
249         dst->lastuse = time;
250 }
251 
252 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
253 {
254         dst->__use++;
255         dst->lastuse = time;
256 }
257 
258 static inline struct dst_entry *dst_clone(struct dst_entry *dst)
259 {
260         if (dst)
261                 atomic_inc(&dst->__refcnt);
262         return dst;
263 }
264 
265 void dst_release(struct dst_entry *dst);
266 
267 static inline void refdst_drop(unsigned long refdst)
268 {
269         if (!(refdst & SKB_DST_NOREF))
270                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
271 }
272 
273 /**
274  * skb_dst_drop - drops skb dst
275  * @skb: buffer
276  *
277  * Drops dst reference count if a reference was taken.
278  */
279 static inline void skb_dst_drop(struct sk_buff *skb)
280 {
281         if (skb->_skb_refdst) {
282                 refdst_drop(skb->_skb_refdst);
283                 skb->_skb_refdst = 0UL;
284         }
285 }
286 
287 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
288 {
289         nskb->_skb_refdst = oskb->_skb_refdst;
290         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
291                 dst_clone(skb_dst(nskb));
292 }
293 
294 /**
295  * skb_dst_force - makes sure skb dst is refcounted
296  * @skb: buffer
297  *
298  * If dst is not yet refcounted, let's do it
299  */
300 static inline void skb_dst_force(struct sk_buff *skb)
301 {
302         if (skb_dst_is_noref(skb)) {
303                 WARN_ON(!rcu_read_lock_held());
304                 skb->_skb_refdst &= ~SKB_DST_NOREF;
305                 dst_clone(skb_dst(skb));
306         }
307 }
308 
309 
310 /**
311  *      __skb_tunnel_rx - prepare skb for rx reinsert
312  *      @skb: buffer
313  *      @dev: tunnel device
314  *      @net: netns for packet i/o
315  *
316  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
317  *      so make some cleanups. (no accounting done)
318  */
319 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
320                                    struct net *net)
321 {
322         skb->dev = dev;
323 
324         /*
325          * Clear hash so that we can recalulate the hash for the
326          * encapsulated packet, unless we have already determine the hash
327          * over the L4 4-tuple.
328          */
329         skb_clear_hash_if_not_l4(skb);
330         skb_set_queue_mapping(skb, 0);
331         skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
332 }
333 
334 /**
335  *      skb_tunnel_rx - prepare skb for rx reinsert
336  *      @skb: buffer
337  *      @dev: tunnel device
338  *
339  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
340  *      so make some cleanups, and perform accounting.
341  *      Note: this accounting is not SMP safe.
342  */
343 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
344                                  struct net *net)
345 {
346         /* TODO : stats should be SMP safe */
347         dev->stats.rx_packets++;
348         dev->stats.rx_bytes += skb->len;
349         __skb_tunnel_rx(skb, dev, net);
350 }
351 
352 /* Children define the path of the packet through the
353  * Linux networking.  Thus, destinations are stackable.
354  */
355 
356 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
357 {
358         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
359 
360         skb_dst_drop(skb);
361         return child;
362 }
363 
364 int dst_discard(struct sk_buff *skb);
365 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
366                 int initial_obsolete, unsigned short flags);
367 void __dst_free(struct dst_entry *dst);
368 struct dst_entry *dst_destroy(struct dst_entry *dst);
369 
370 static inline void dst_free(struct dst_entry *dst)
371 {
372         if (dst->obsolete > 0)
373                 return;
374         if (!atomic_read(&dst->__refcnt)) {
375                 dst = dst_destroy(dst);
376                 if (!dst)
377                         return;
378         }
379         __dst_free(dst);
380 }
381 
382 static inline void dst_rcu_free(struct rcu_head *head)
383 {
384         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
385         dst_free(dst);
386 }
387 
388 static inline void dst_confirm(struct dst_entry *dst)
389 {
390         dst->pending_confirm = 1;
391 }
392 
393 static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
394                                    struct sk_buff *skb)
395 {
396         const struct hh_cache *hh;
397 
398         if (dst->pending_confirm) {
399                 unsigned long now = jiffies;
400 
401                 dst->pending_confirm = 0;
402                 /* avoid dirtying neighbour */
403                 if (n->confirmed != now)
404                         n->confirmed = now;
405         }
406 
407         hh = &n->hh;
408         if ((n->nud_state & NUD_CONNECTED) && hh->hh_len)
409                 return neigh_hh_output(hh, skb);
410         else
411                 return n->output(n, skb);
412 }
413 
414 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
415 {
416         struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
417         return IS_ERR(n) ? NULL : n;
418 }
419 
420 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
421                                                      struct sk_buff *skb)
422 {
423         struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
424         return IS_ERR(n) ? NULL : n;
425 }
426 
427 static inline void dst_link_failure(struct sk_buff *skb)
428 {
429         struct dst_entry *dst = skb_dst(skb);
430         if (dst && dst->ops && dst->ops->link_failure)
431                 dst->ops->link_failure(skb);
432 }
433 
434 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
435 {
436         unsigned long expires = jiffies + timeout;
437 
438         if (expires == 0)
439                 expires = 1;
440 
441         if (dst->expires == 0 || time_before(expires, dst->expires))
442                 dst->expires = expires;
443 }
444 
445 /* Output packet to network from transport.  */
446 static inline int dst_output(struct sk_buff *skb)
447 {
448         return skb_dst(skb)->output(skb);
449 }
450 
451 /* Input packet from network to transport.  */
452 static inline int dst_input(struct sk_buff *skb)
453 {
454         return skb_dst(skb)->input(skb);
455 }
456 
457 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
458 {
459         if (dst->obsolete)
460                 dst = dst->ops->check(dst, cookie);
461         return dst;
462 }
463 
464 void dst_init(void);
465 
466 /* Flags for xfrm_lookup flags argument. */
467 enum {
468         XFRM_LOOKUP_ICMP = 1 << 0,
469 };
470 
471 struct flowi;
472 #ifndef CONFIG_XFRM
473 static inline struct dst_entry *xfrm_lookup(struct net *net,
474                                             struct dst_entry *dst_orig,
475                                             const struct flowi *fl, struct sock *sk,
476                                             int flags)
477 {
478         return dst_orig;
479 } 
480 
481 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
482 {
483         return NULL;
484 }
485 
486 #else
487 struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
488                               const struct flowi *fl, struct sock *sk,
489                               int flags);
490 
491 /* skb attached with this dst needs transformation if dst->xfrm is valid */
492 static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
493 {
494         return dst->xfrm;
495 }
496 #endif
497 
498 #endif /* _NET_DST_H */
499 

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