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/jiffies.h>
  16 #include <net/neighbour.h>
  17 #include <asm/processor.h>
  18
  19 #define DST_GC_MIN      (HZ/10)
  20 #define DST_GC_INC      (HZ/2)
  21 #define DST_GC_MAX      (120*HZ)
  22
  23 /* Each dst_entry has reference count and sits in some parent list(s).
  24  * When it is removed from parent list, it is "freed" (dst_free).
  25  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
  26  * is zero, it can be destroyed immediately, otherwise it is added
  27  * to gc list and garbage collector periodically checks the refcnt.
  28  */
  29
  30 struct sk_buff;
  31
  32 struct dst_entry {
  33         struct rcu_head         rcu_head;
  34         struct dst_entry        *child;
  35         struct net_device       *dev;
  36         struct  dst_ops         *ops;
  37         unsigned long           _metrics;
  38         unsigned long           expires;
  39         struct dst_entry        *path;
  40         struct neighbour        *_neighbour;
  41 #ifdef CONFIG_XFRM
  42         struct xfrm_state       *xfrm;
  43 #else
  44         void                    *__pad1;
  45 #endif
  46         int                     (*input)(struct sk_buff*);
  47         int                     (*output)(struct sk_buff*);
  48
  49         int                     flags;
  50 #define DST_HOST                0x0001
  51 #define DST_NOXFRM              0x0002
  52 #define DST_NOPOLICY            0x0004
  53 #define DST_NOHASH              0x0008
  54 #define DST_NOCACHE             0x0010
  55 #define DST_NOCOUNT             0x0020
  56
  57         short                   error;
  58         short                   obsolete;
  59         unsigned short          header_len;     /* more space at head required */
  60         unsigned short          trailer_len;    /* space to reserve at tail */
  61 #ifdef CONFIG_IP_ROUTE_CLASSID
  62         __u32                   tclassid;
  63 #else
  64         __u32                   __pad2;
  65 #endif
  66
  67         /*
  68          * Align __refcnt to a 64 bytes alignment
  69          * (L1_CACHE_SIZE would be too much)
  70          */
  71 #ifdef CONFIG_64BIT
  72         long                    __pad_to_align_refcnt[2];
  73 #endif
  74         /*
  75          * __refcnt wants to be on a different cache line from
  76          * input/output/ops or performance tanks badly
  77          */
  78         atomic_t                __refcnt;       /* client references    */
  79         int                     __use;
  80         unsigned long           lastuse;
  81         union {
  82                 struct dst_entry        *next;
  83                 struct rtable __rcu     *rt_next;
  84                 struct rt6_info         *rt6_next;
  85                 struct dn_route __rcu   *dn_next;
  86         };
  87 };
  88
  89 static inline struct neighbour *dst_get_neighbour(struct dst_entry *dst)
  90 {
  91         return dst->_neighbour;
  92 }
  93
  94 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
  95 {
  96         dst->_neighbour = neigh;
  97 }
  98
  99 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 100 extern const u32 dst_default_metrics[RTAX_MAX];
 101
 102 #define DST_METRICS_READ_ONLY   0x1UL
 103 #define __DST_METRICS_PTR(Y)    \
 104         ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
 105 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 106
 107 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 108 {
 109         return dst->_metrics & DST_METRICS_READ_ONLY;
 110 }
 111
 112 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 113
 114 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 115 {
 116         unsigned long val = dst->_metrics;
 117         if (!(val & DST_METRICS_READ_ONLY))
 118                 __dst_destroy_metrics_generic(dst, val);
 119 }
 120
 121 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 122 {
 123         unsigned long p = dst->_metrics;
 124
 125         BUG_ON(!p);
 126
 127         if (p & DST_METRICS_READ_ONLY)
 128                 return dst->ops->cow_metrics(dst, p);
 129         return __DST_METRICS_PTR(p);
 130 }
 131
 132 /* This may only be invoked before the entry has reached global
 133  * visibility.
 134  */
 135 static inline void dst_init_metrics(struct dst_entry *dst,
 136                                     const u32 *src_metrics,
 137                                     bool read_only)
 138 {
 139         dst->_metrics = ((unsigned long) src_metrics) |
 140                 (read_only ? DST_METRICS_READ_ONLY : 0);
 141 }
 142
 143 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 144 {
 145         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 146
 147         if (dst_metrics) {
 148                 u32 *src_metrics = DST_METRICS_PTR(src);
 149
 150                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 151         }
 152 }
 153
 154 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 155 {
 156         return DST_METRICS_PTR(dst);
 157 }
 158
 159 static inline u32
 160 dst_metric_raw(const struct dst_entry *dst, const int metric)
 161 {
 162         u32 *p = DST_METRICS_PTR(dst);
 163
 164         return p[metric-1];
 165 }
 166
 167 static inline u32
 168 dst_metric(const struct dst_entry *dst, const int metric)
 169 {
 170         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 171                      metric == RTAX_ADVMSS ||
 172                      metric == RTAX_MTU);
 173         return dst_metric_raw(dst, metric);
 174 }
 175
 176 static inline u32
 177 dst_metric_advmss(const struct dst_entry *dst)
 178 {
 179         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 180
 181         if (!advmss)
 182                 advmss = dst->ops->default_advmss(dst);
 183
 184         return advmss;
 185 }
 186
 187 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 188 {
 189         u32 *p = dst_metrics_write_ptr(dst);
 190
 191         if (p)
 192                 p[metric-1] = val;
 193 }
 194
 195 static inline u32
 196 dst_feature(const struct dst_entry *dst, u32 feature)
 197 {
 198         return dst_metric(dst, RTAX_FEATURES) & feature;
 199 }
 200
 201 static inline u32 dst_mtu(const struct dst_entry *dst)
 202 {
 203         u32 mtu = dst_metric_raw(dst, RTAX_MTU);
 204
 205         if (!mtu)
 206                 mtu = dst->ops->default_mtu(dst);
 207
 208         return mtu;
 209 }
 210
 211 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 212 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 213 {
 214         return msecs_to_jiffies(dst_metric(dst, metric));
 215 }
 216
 217 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 218                                       unsigned long rtt)
 219 {
 220         dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
 221 }
 222
 223 static inline u32
 224 dst_allfrag(const struct dst_entry *dst)
 225 {
 226         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 227         return ret;
 228 }
 229
 230 static inline int
 231 dst_metric_locked(const struct dst_entry *dst, int metric)
 232 {
 233         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 234 }
 235
 236 static inline void dst_hold(struct dst_entry * dst)
 237 {
 238         /*
 239          * If your kernel compilation stops here, please check
 240          * __pad_to_align_refcnt declaration in struct dst_entry
 241          */
 242         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 243         atomic_inc(&dst->__refcnt);
 244 }
 245
 246 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 247 {
 248         dst_hold(dst);
 249         dst->__use++;
 250         dst->lastuse = time;
 251 }
 252
 253 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 254 {
 255         dst->__use++;
 256         dst->lastuse = time;
 257 }
 258
 259 static inline
 260 struct dst_entry * dst_clone(struct dst_entry * dst)
 261 {
 262         if (dst)
 263                 atomic_inc(&dst->__refcnt);
 264         return dst;
 265 }
 266
 267 extern void dst_release(struct dst_entry *dst);
 268
 269 static inline void refdst_drop(unsigned long refdst)
 270 {
 271         if (!(refdst & SKB_DST_NOREF))
 272                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 273 }
 274
 275 /**
 276  * skb_dst_drop - drops skb dst
 277  * @skb: buffer
 278  *
 279  * Drops dst reference count if a reference was taken.
 280  */
 281 static inline void skb_dst_drop(struct sk_buff *skb)
 282 {
 283         if (skb->_skb_refdst) {
 284                 refdst_drop(skb->_skb_refdst);
 285                 skb->_skb_refdst = 0UL;
 286         }
 287 }
 288
 289 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 290 {
 291         nskb->_skb_refdst = oskb->_skb_refdst;
 292         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 293                 dst_clone(skb_dst(nskb));
 294 }
 295
 296 /**
 297  * skb_dst_force - makes sure skb dst is refcounted
 298  * @skb: buffer
 299  *
 300  * If dst is not yet refcounted, let's do it
 301  */
 302 static inline void skb_dst_force(struct sk_buff *skb)
 303 {
 304         if (skb_dst_is_noref(skb)) {
 305                 WARN_ON(!rcu_read_lock_held());
 306                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 307                 dst_clone(skb_dst(skb));
 308         }
 309 }
 310
 311
 312 /**
 313  *      __skb_tunnel_rx - prepare skb for rx reinsert
 314  *      @skb: buffer
 315  *      @dev: tunnel device
 316  *
 317  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 318  *      so make some cleanups. (no accounting done)
 319  */
 320 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 321 {
 322         skb->dev = dev;
 323         skb->rxhash = 0;
 324         skb_set_queue_mapping(skb, 0);
 325         skb_dst_drop(skb);
 326         nf_reset(skb);
 327 }
 328
 329 /**
 330  *      skb_tunnel_rx - prepare skb for rx reinsert
 331  *      @skb: buffer
 332  *      @dev: tunnel device
 333  *
 334  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 335  *      so make some cleanups, and perform accounting.
 336  *      Note: this accounting is not SMP safe.
 337  */
 338 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 339 {
 340         /* TODO : stats should be SMP safe */
 341         dev->stats.rx_packets++;
 342         dev->stats.rx_bytes += skb->len;
 343         __skb_tunnel_rx(skb, dev);
 344 }
 345
 346 /* Children define the path of the packet through the
 347  * Linux networking.  Thus, destinations are stackable.
 348  */
 349
 350 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 351 {
 352         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 353
 354         skb_dst_drop(skb);
 355         return child;
 356 }
 357
 358 extern int dst_discard(struct sk_buff *skb);
 359 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
 360                        int initial_ref, int initial_obsolete, int flags);
 361 extern void __dst_free(struct dst_entry * dst);
 362 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 363
 364 static inline void dst_free(struct dst_entry * dst)
 365 {
 366         if (dst->obsolete > 1)
 367                 return;
 368         if (!atomic_read(&dst->__refcnt)) {
 369                 dst = dst_destroy(dst);
 370                 if (!dst)
 371                         return;
 372         }
 373         __dst_free(dst);
 374 }
 375
 376 static inline void dst_rcu_free(struct rcu_head *head)
 377 {
 378         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 379         dst_free(dst);
 380 }
 381
 382 static inline void dst_confirm(struct dst_entry *dst)
 383 {
 384         if (dst) {
 385                 struct neighbour *n = dst_get_neighbour(dst);
 386                 neigh_confirm(n);
 387         }
 388 }
 389
 390 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 391 {
 392         return dst->ops->neigh_lookup(dst, daddr);
 393 }
 394
 395 static inline void dst_link_failure(struct sk_buff *skb)
 396 {
 397         struct dst_entry *dst = skb_dst(skb);
 398         if (dst && dst->ops && dst->ops->link_failure)
 399                 dst->ops->link_failure(skb);
 400 }
 401
 402 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 403 {
 404         unsigned long expires = jiffies + timeout;
 405
 406         if (expires == 0)
 407                 expires = 1;
 408
 409         if (dst->expires == 0 || time_before(expires, dst->expires))
 410                 dst->expires = expires;
 411 }
 412
 413 /* Output packet to network from transport.  */
 414 static inline int dst_output(struct sk_buff *skb)
 415 {
 416         return skb_dst(skb)->output(skb);
 417 }
 418
 419 /* Input packet from network to transport.  */
 420 static inline int dst_input(struct sk_buff *skb)
 421 {
 422         return skb_dst(skb)->input(skb);
 423 }
 424
 425 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 426 {
 427         if (dst->obsolete)
 428                 dst = dst->ops->check(dst, cookie);
 429         return dst;
 430 }
 431
 432 extern void             dst_init(void);
 433
 434 /* Flags for xfrm_lookup flags argument. */
 435 enum {
 436         XFRM_LOOKUP_ICMP = 1 << 0,
 437 };
 438
 439 struct flowi;
 440 #ifndef CONFIG_XFRM
 441 static inline struct dst_entry *xfrm_lookup(struct net *net,
 442                                             struct dst_entry *dst_orig,
 443                                             const struct flowi *fl, struct sock *sk,
 444                                             int flags)
 445 {
 446         return dst_orig;
 447 }
 448 #else
 449 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 450                                      const struct flowi *fl, struct sock *sk,
 451                                      int flags);
 452 #endif
 453
 454 #endif /* _NET_DST_H */