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 __rcu  *_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 #define DST_NOPEER              0x0040
  57
  58         short                   error;
  59         short                   obsolete;
  60         unsigned short          header_len;     /* more space at head required */
  61         unsigned short          trailer_len;    /* space to reserve at tail */
  62 #ifdef CONFIG_IP_ROUTE_CLASSID
  63         __u32                   tclassid;
  64 #else
  65         __u32                   __pad2;
  66 #endif
  67
  68         /*
  69          * Align __refcnt to a 64 bytes alignment
  70          * (L1_CACHE_SIZE would be too much)
  71          */
  72 #ifdef CONFIG_64BIT
  73         long                    __pad_to_align_refcnt[2];
  74 #endif
  75         /*
  76          * __refcnt wants to be on a different cache line from
  77          * input/output/ops or performance tanks badly
  78          */
  79         atomic_t                __refcnt;       /* client references    */
  80         int                     __use;
  81         unsigned long           lastuse;
  82         union {
  83                 struct dst_entry        *next;
  84                 struct rtable __rcu     *rt_next;
  85                 struct rt6_info         *rt6_next;
  86                 struct dn_route __rcu   *dn_next;
  87         };
  88 };
  89
  90 static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst)
  91 {
  92         return rcu_dereference(dst->_neighbour);
  93 }
  94
  95 static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst)
  96 {
  97         return rcu_dereference_raw(dst->_neighbour);
  98 }
  99
 100 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
 101 {
 102         rcu_assign_pointer(dst->_neighbour, neigh);
 103 }
 104
 105 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 106 extern const u32 dst_default_metrics[RTAX_MAX];
 107
 108 #define DST_METRICS_READ_ONLY   0x1UL
 109 #define __DST_METRICS_PTR(Y)    \
 110         ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
 111 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 112
 113 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 114 {
 115         return dst->_metrics & DST_METRICS_READ_ONLY;
 116 }
 117
 118 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 119
 120 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 121 {
 122         unsigned long val = dst->_metrics;
 123         if (!(val & DST_METRICS_READ_ONLY))
 124                 __dst_destroy_metrics_generic(dst, val);
 125 }
 126
 127 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 128 {
 129         unsigned long p = dst->_metrics;
 130
 131         BUG_ON(!p);
 132
 133         if (p & DST_METRICS_READ_ONLY)
 134                 return dst->ops->cow_metrics(dst, p);
 135         return __DST_METRICS_PTR(p);
 136 }
 137
 138 /* This may only be invoked before the entry has reached global
 139  * visibility.
 140  */
 141 static inline void dst_init_metrics(struct dst_entry *dst,
 142                                     const u32 *src_metrics,
 143                                     bool read_only)
 144 {
 145         dst->_metrics = ((unsigned long) src_metrics) |
 146                 (read_only ? DST_METRICS_READ_ONLY : 0);
 147 }
 148
 149 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 150 {
 151         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 152
 153         if (dst_metrics) {
 154                 u32 *src_metrics = DST_METRICS_PTR(src);
 155
 156                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 157         }
 158 }
 159
 160 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 161 {
 162         return DST_METRICS_PTR(dst);
 163 }
 164
 165 static inline u32
 166 dst_metric_raw(const struct dst_entry *dst, const int metric)
 167 {
 168         u32 *p = DST_METRICS_PTR(dst);
 169
 170         return p[metric-1];
 171 }
 172
 173 static inline u32
 174 dst_metric(const struct dst_entry *dst, const int metric)
 175 {
 176         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 177                      metric == RTAX_ADVMSS ||
 178                      metric == RTAX_MTU);
 179         return dst_metric_raw(dst, metric);
 180 }
 181
 182 static inline u32
 183 dst_metric_advmss(const struct dst_entry *dst)
 184 {
 185         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 186
 187         if (!advmss)
 188                 advmss = dst->ops->default_advmss(dst);
 189
 190         return advmss;
 191 }
 192
 193 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 194 {
 195         u32 *p = dst_metrics_write_ptr(dst);
 196
 197         if (p)
 198                 p[metric-1] = val;
 199 }
 200
 201 static inline u32
 202 dst_feature(const struct dst_entry *dst, u32 feature)
 203 {
 204         return dst_metric(dst, RTAX_FEATURES) & feature;
 205 }
 206
 207 static inline u32 dst_mtu(const struct dst_entry *dst)
 208 {
 209         return dst->ops->mtu(dst);
 210 }
 211
 212 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 213 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 214 {
 215         return msecs_to_jiffies(dst_metric(dst, metric));
 216 }
 217
 218 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 219                                       unsigned long rtt)
 220 {
 221         dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
 222 }
 223
 224 static inline u32
 225 dst_allfrag(const struct dst_entry *dst)
 226 {
 227         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 228         return ret;
 229 }
 230
 231 static inline int
 232 dst_metric_locked(const struct dst_entry *dst, int metric)
 233 {
 234         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 235 }
 236
 237 static inline void dst_hold(struct dst_entry * dst)
 238 {
 239         /*
 240          * If your kernel compilation stops here, please check
 241          * __pad_to_align_refcnt declaration in struct dst_entry
 242          */
 243         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 244         atomic_inc(&dst->__refcnt);
 245 }
 246
 247 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 248 {
 249         dst_hold(dst);
 250         dst->__use++;
 251         dst->lastuse = time;
 252 }
 253
 254 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 255 {
 256         dst->__use++;
 257         dst->lastuse = time;
 258 }
 259
 260 static inline
 261 struct dst_entry * dst_clone(struct dst_entry * dst)
 262 {
 263         if (dst)
 264                 atomic_inc(&dst->__refcnt);
 265         return dst;
 266 }
 267
 268 extern void dst_release(struct dst_entry *dst);
 269
 270 static inline void refdst_drop(unsigned long refdst)
 271 {
 272         if (!(refdst & SKB_DST_NOREF))
 273                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 274 }
 275
 276 /**
 277  * skb_dst_drop - drops skb dst
 278  * @skb: buffer
 279  *
 280  * Drops dst reference count if a reference was taken.
 281  */
 282 static inline void skb_dst_drop(struct sk_buff *skb)
 283 {
 284         if (skb->_skb_refdst) {
 285                 refdst_drop(skb->_skb_refdst);
 286                 skb->_skb_refdst = 0UL;
 287         }
 288 }
 289
 290 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 291 {
 292         nskb->_skb_refdst = oskb->_skb_refdst;
 293         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 294                 dst_clone(skb_dst(nskb));
 295 }
 296
 297 /**
 298  * skb_dst_force - makes sure skb dst is refcounted
 299  * @skb: buffer
 300  *
 301  * If dst is not yet refcounted, let's do it
 302  */
 303 static inline void skb_dst_force(struct sk_buff *skb)
 304 {
 305         if (skb_dst_is_noref(skb)) {
 306                 WARN_ON(!rcu_read_lock_held());
 307                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 308                 dst_clone(skb_dst(skb));
 309         }
 310 }
 311
 312
 313 /**
 314  *      __skb_tunnel_rx - prepare skb for rx reinsert
 315  *      @skb: buffer
 316  *      @dev: tunnel device
 317  *
 318  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 319  *      so make some cleanups. (no accounting done)
 320  */
 321 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 322 {
 323         skb->dev = dev;
 324
 325         /*
 326          * Clear rxhash so that we can recalulate the hash for the
 327          * encapsulated packet, unless we have already determine the hash
 328          * over the L4 4-tuple.
 329          */
 330         if (!skb->l4_rxhash)
 331                 skb->rxhash = 0;
 332         skb_set_queue_mapping(skb, 0);
 333         skb_dst_drop(skb);
 334         nf_reset(skb);
 335 }
 336
 337 /**
 338  *      skb_tunnel_rx - prepare skb for rx reinsert
 339  *      @skb: buffer
 340  *      @dev: tunnel device
 341  *
 342  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 343  *      so make some cleanups, and perform accounting.
 344  *      Note: this accounting is not SMP safe.
 345  */
 346 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 347 {
 348         /* TODO : stats should be SMP safe */
 349         dev->stats.rx_packets++;
 350         dev->stats.rx_bytes += skb->len;
 351         __skb_tunnel_rx(skb, dev);
 352 }
 353
 354 /* Children define the path of the packet through the
 355  * Linux networking.  Thus, destinations are stackable.
 356  */
 357
 358 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 359 {
 360         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 361
 362         skb_dst_drop(skb);
 363         return child;
 364 }
 365
 366 extern int dst_discard(struct sk_buff *skb);
 367 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
 368                        int initial_ref, int initial_obsolete, int flags);
 369 extern void __dst_free(struct dst_entry * dst);
 370 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 371
 372 static inline void dst_free(struct dst_entry * dst)
 373 {
 374         if (dst->obsolete > 1)
 375                 return;
 376         if (!atomic_read(&dst->__refcnt)) {
 377                 dst = dst_destroy(dst);
 378                 if (!dst)
 379                         return;
 380         }
 381         __dst_free(dst);
 382 }
 383
 384 static inline void dst_rcu_free(struct rcu_head *head)
 385 {
 386         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 387         dst_free(dst);
 388 }
 389
 390 static inline void dst_confirm(struct dst_entry *dst)
 391 {
 392         if (dst) {
 393                 struct neighbour *n;
 394
 395                 rcu_read_lock();
 396                 n = dst_get_neighbour_noref(dst);
 397                 neigh_confirm(n);
 398                 rcu_read_unlock();
 399         }
 400 }
 401
 402 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 403 {
 404         return dst->ops->neigh_lookup(dst, daddr);
 405 }
 406
 407 static inline void dst_link_failure(struct sk_buff *skb)
 408 {
 409         struct dst_entry *dst = skb_dst(skb);
 410         if (dst && dst->ops && dst->ops->link_failure)
 411                 dst->ops->link_failure(skb);
 412 }
 413
 414 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 415 {
 416         unsigned long expires = jiffies + timeout;
 417
 418         if (expires == 0)
 419                 expires = 1;
 420
 421         if (dst->expires == 0 || time_before(expires, dst->expires))
 422                 dst->expires = expires;
 423 }
 424
 425 /* Output packet to network from transport.  */
 426 static inline int dst_output(struct sk_buff *skb)
 427 {
 428         return skb_dst(skb)->output(skb);
 429 }
 430
 431 /* Input packet from network to transport.  */
 432 static inline int dst_input(struct sk_buff *skb)
 433 {
 434         return skb_dst(skb)->input(skb);
 435 }
 436
 437 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 438 {
 439         if (dst->obsolete)
 440                 dst = dst->ops->check(dst, cookie);
 441         return dst;
 442 }
 443
 444 extern void             dst_init(void);
 445
 446 /* Flags for xfrm_lookup flags argument. */
 447 enum {
 448         XFRM_LOOKUP_ICMP = 1 << 0,
 449 };
 450
 451 struct flowi;
 452 #ifndef CONFIG_XFRM
 453 static inline struct dst_entry *xfrm_lookup(struct net *net,
 454                                             struct dst_entry *dst_orig,
 455                                             const struct flowi *fl, struct sock *sk,
 456                                             int flags)
 457 {
 458         return dst_orig;
 459 }
 460 #else
 461 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 462                                      const struct flowi *fl, struct sock *sk,
 463                                      int flags);
 464 #endif
 465
 466 #endif /* _NET_DST_H */