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         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
  97 static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst)
  98 {
  99         return rcu_dereference(dst->_neighbour);
 100 }
 101
 102 static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst)
 103 {
 104         return rcu_dereference_raw(dst->_neighbour);
 105 }
 106
 107 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
 108 {
 109         rcu_assign_pointer(dst->_neighbour, neigh);
 110 }
 111
 112 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 113 extern 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
 120 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 121 {
 122         return dst->_metrics & DST_METRICS_READ_ONLY;
 123 }
 124
 125 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 126
 127 static 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
 134 static 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  */
 148 static 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
 156 static 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
 167 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 168 {
 169         return DST_METRICS_PTR(dst);
 170 }
 171
 172 static inline u32
 173 dst_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
 180 static inline u32
 181 dst_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
 189 static inline u32
 190 dst_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
 200 static 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
 208 static inline u32
 209 dst_feature(const struct dst_entry *dst, u32 feature)
 210 {
 211         return dst_metric(dst, RTAX_FEATURES) & feature;
 212 }
 213
 214 static 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 */
 220 static 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
 225 static 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
 231 static inline u32
 232 dst_allfrag(const struct dst_entry *dst)
 233 {
 234         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 235         return ret;
 236 }
 237
 238 static inline int
 239 dst_metric_locked(const struct dst_entry *dst, int metric)
 240 {
 241         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 242 }
 243
 244 static 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
 254 static 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
 261 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 262 {
 263         dst->__use++;
 264         dst->lastuse = time;
 265 }
 266
 267 static inline
 268 struct dst_entry * dst_clone(struct dst_entry * dst)
 269 {
 270         if (dst)
 271                 atomic_inc(&dst->__refcnt);
 272         return dst;
 273 }
 274
 275 extern void dst_release(struct dst_entry *dst);
 276
 277 static 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  */
 289 static 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
 297 static 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  */
 310 static 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  */
 328 static 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  */
 353 static 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
 365 static 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
 373 extern int dst_discard(struct sk_buff *skb);
 374 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
 375                        int initial_ref, int initial_obsolete, int flags);
 376 extern void __dst_free(struct dst_entry * dst);
 377 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 378
 379 static 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
 391 static 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
 397 static 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
 409 static 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
 414 static 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
 421 static 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.  */
 433 static 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.  */
 439 static inline int dst_input(struct sk_buff *skb)
 440 {
 441         return skb_dst(skb)->input(skb);
 442 }
 443
 444 static 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
 451 extern void             dst_init(void);
 452
 453 /* Flags for xfrm_lookup flags argument. */
 454 enum {
 455         XFRM_LOOKUP_ICMP = 1 << 0,
 456 };
 457
 458 struct flowi;
 459 #ifndef CONFIG_XFRM
 460 static 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
 468 extern 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 */