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
  64         short                   error;
  65         short                   obsolete;
  66         unsigned short          header_len;     /* more space at head required */
  67         unsigned short          trailer_len;    /* space to reserve at tail */
  68 #ifdef CONFIG_IP_ROUTE_CLASSID
  69         __u32                   tclassid;
  70 #else
  71         __u32                   __pad2;
  72 #endif
  73
  74         /*
  75          * Align __refcnt to a 64 bytes alignment
  76          * (L1_CACHE_SIZE would be too much)
  77          */
  78 #ifdef CONFIG_64BIT
  79         long                    __pad_to_align_refcnt[2];
  80 #endif
  81         /*
  82          * __refcnt wants to be on a different cache line from
  83          * input/output/ops or performance tanks badly
  84          */
  85         atomic_t                __refcnt;       /* client references    */
  86         int                     __use;
  87         unsigned long           lastuse;
  88         union {
  89                 struct dst_entry        *next;
  90                 struct rtable __rcu     *rt_next;
  91                 struct rt6_info         *rt6_next;
  92                 struct dn_route __rcu   *dn_next;
  93         };
  94 };
  95
  96 static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst)
  97 {
  98         return rcu_dereference(dst->_neighbour);
  99 }
 100
 101 static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst)
 102 {
 103         return rcu_dereference_raw(dst->_neighbour);
 104 }
 105
 106 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
 107 {
 108         rcu_assign_pointer(dst->_neighbour, neigh);
 109 }
 110
 111 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 112 extern const u32 dst_default_metrics[RTAX_MAX];
 113
 114 #define DST_METRICS_READ_ONLY   0x1UL
 115 #define __DST_METRICS_PTR(Y)    \
 116         ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
 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 extern 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 static inline u32
 208 dst_feature(const struct dst_entry *dst, u32 feature)
 209 {
 210         return dst_metric(dst, RTAX_FEATURES) & feature;
 211 }
 212
 213 static inline u32 dst_mtu(const struct dst_entry *dst)
 214 {
 215         return dst->ops->mtu(dst);
 216 }
 217
 218 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 219 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 220 {
 221         return msecs_to_jiffies(dst_metric(dst, metric));
 222 }
 223
 224 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 225                                       unsigned long rtt)
 226 {
 227         dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
 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
 267 struct dst_entry * dst_clone(struct dst_entry * dst)
 268 {
 269         if (dst)
 270                 atomic_inc(&dst->__refcnt);
 271         return dst;
 272 }
 273
 274 extern void dst_release(struct dst_entry *dst);
 275
 276 static inline void refdst_drop(unsigned long refdst)
 277 {
 278         if (!(refdst & SKB_DST_NOREF))
 279                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 280 }
 281
 282 /**
 283  * skb_dst_drop - drops skb dst
 284  * @skb: buffer
 285  *
 286  * Drops dst reference count if a reference was taken.
 287  */
 288 static inline void skb_dst_drop(struct sk_buff *skb)
 289 {
 290         if (skb->_skb_refdst) {
 291                 refdst_drop(skb->_skb_refdst);
 292                 skb->_skb_refdst = 0UL;
 293         }
 294 }
 295
 296 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 297 {
 298         nskb->_skb_refdst = oskb->_skb_refdst;
 299         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 300                 dst_clone(skb_dst(nskb));
 301 }
 302
 303 /**
 304  * skb_dst_force - makes sure skb dst is refcounted
 305  * @skb: buffer
 306  *
 307  * If dst is not yet refcounted, let's do it
 308  */
 309 static inline void skb_dst_force(struct sk_buff *skb)
 310 {
 311         if (skb_dst_is_noref(skb)) {
 312                 WARN_ON(!rcu_read_lock_held());
 313                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 314                 dst_clone(skb_dst(skb));
 315         }
 316 }
 317
 318
 319 /**
 320  *      __skb_tunnel_rx - prepare skb for rx reinsert
 321  *      @skb: buffer
 322  *      @dev: tunnel device
 323  *
 324  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 325  *      so make some cleanups. (no accounting done)
 326  */
 327 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 328 {
 329         skb->dev = dev;
 330
 331         /*
 332          * Clear rxhash so that we can recalulate the hash for the
 333          * encapsulated packet, unless we have already determine the hash
 334          * over the L4 4-tuple.
 335          */
 336         if (!skb->l4_rxhash)
 337                 skb->rxhash = 0;
 338         skb_set_queue_mapping(skb, 0);
 339         skb_dst_drop(skb);
 340         nf_reset(skb);
 341 }
 342
 343 /**
 344  *      skb_tunnel_rx - prepare skb for rx reinsert
 345  *      @skb: buffer
 346  *      @dev: tunnel device
 347  *
 348  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 349  *      so make some cleanups, and perform accounting.
 350  *      Note: this accounting is not SMP safe.
 351  */
 352 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 353 {
 354         /* TODO : stats should be SMP safe */
 355         dev->stats.rx_packets++;
 356         dev->stats.rx_bytes += skb->len;
 357         __skb_tunnel_rx(skb, dev);
 358 }
 359
 360 /* Children define the path of the packet through the
 361  * Linux networking.  Thus, destinations are stackable.
 362  */
 363
 364 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 365 {
 366         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 367
 368         skb_dst_drop(skb);
 369         return child;
 370 }
 371
 372 extern int dst_discard(struct sk_buff *skb);
 373 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
 374                        int initial_ref, int initial_obsolete, int flags);
 375 extern void __dst_free(struct dst_entry * dst);
 376 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 377
 378 static inline void dst_free(struct dst_entry * dst)
 379 {
 380         if (dst->obsolete > 1)
 381                 return;
 382         if (!atomic_read(&dst->__refcnt)) {
 383                 dst = dst_destroy(dst);
 384                 if (!dst)
 385                         return;
 386         }
 387         __dst_free(dst);
 388 }
 389
 390 static inline void dst_rcu_free(struct rcu_head *head)
 391 {
 392         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 393         dst_free(dst);
 394 }
 395
 396 static inline void dst_confirm(struct dst_entry *dst)
 397 {
 398         if (dst) {
 399                 struct neighbour *n;
 400
 401                 rcu_read_lock();
 402                 n = dst_get_neighbour_noref(dst);
 403                 neigh_confirm(n);
 404                 rcu_read_unlock();
 405         }
 406 }
 407
 408 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 409 {
 410         return dst->ops->neigh_lookup(dst, daddr);
 411 }
 412
 413 static inline void dst_link_failure(struct sk_buff *skb)
 414 {
 415         struct dst_entry *dst = skb_dst(skb);
 416         if (dst && dst->ops && dst->ops->link_failure)
 417                 dst->ops->link_failure(skb);
 418 }
 419
 420 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 421 {
 422         unsigned long expires = jiffies + timeout;
 423
 424         if (expires == 0)
 425                 expires = 1;
 426
 427         if (dst->expires == 0 || time_before(expires, dst->expires))
 428                 dst->expires = expires;
 429 }
 430
 431 /* Output packet to network from transport.  */
 432 static inline int dst_output(struct sk_buff *skb)
 433 {
 434         return skb_dst(skb)->output(skb);
 435 }
 436
 437 /* Input packet from network to transport.  */
 438 static inline int dst_input(struct sk_buff *skb)
 439 {
 440         return skb_dst(skb)->input(skb);
 441 }
 442
 443 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 444 {
 445         if (dst->obsolete)
 446                 dst = dst->ops->check(dst, cookie);
 447         return dst;
 448 }
 449
 450 extern void             dst_init(void);
 451
 452 /* Flags for xfrm_lookup flags argument. */
 453 enum {
 454         XFRM_LOOKUP_ICMP = 1 << 0,
 455 };
 456
 457 struct flowi;
 458 #ifndef CONFIG_XFRM
 459 static inline struct dst_entry *xfrm_lookup(struct net *net,
 460                                             struct dst_entry *dst_orig,
 461                                             const struct flowi *fl, struct sock *sk,
 462                                             int flags)
 463 {
 464         return dst_orig;
 465 }
 466 #else
 467 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 468                                      const struct flowi *fl, struct sock *sk,
 469                                      int flags);
 470 #endif
 471
 472 #endif /* _NET_DST_H */