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