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         unsigned long           expires;
  40         struct dst_entry        *path;
  41         struct neighbour __rcu  *_neighbour;
  42 #ifdef CONFIG_XFRM
  43         struct xfrm_state       *xfrm;
  44 #else
  45         void                    *__pad1;
  46 #endif
  47         int                     (*input)(struct sk_buff*);
  48         int                     (*output)(struct sk_buff*);
  49
  50         int                     flags;
  51 #define DST_HOST                0x0001
  52 #define DST_NOXFRM              0x0002
  53 #define DST_NOPOLICY            0x0004
  54 #define DST_NOHASH              0x0008
  55 #define DST_NOCACHE             0x0010
  56 #define DST_NOCOUNT             0x0020
  57 #define DST_NOPEER              0x0040
  58
  59         short                   error;
  60         short                   obsolete;
  61         unsigned short          header_len;     /* more space at head required */
  62         unsigned short          trailer_len;    /* space to reserve at tail */
  63 #ifdef CONFIG_IP_ROUTE_CLASSID
  64         __u32                   tclassid;
  65 #else
  66         __u32                   __pad2;
  67 #endif
  68
  69         /*
  70          * Align __refcnt to a 64 bytes alignment
  71          * (L1_CACHE_SIZE would be too much)
  72          */
  73 #ifdef CONFIG_64BIT
  74         long                    __pad_to_align_refcnt[2];
  75 #endif
  76         /*
  77          * __refcnt wants to be on a different cache line from
  78          * input/output/ops or performance tanks badly
  79          */
  80         atomic_t                __refcnt;       /* client references    */
  81         int                     __use;
  82         unsigned long           lastuse;
  83         union {
  84                 struct dst_entry        *next;
  85                 struct rtable __rcu     *rt_next;
  86                 struct rt6_info         *rt6_next;
  87                 struct dn_route __rcu   *dn_next;
  88         };
  89 };
  90
  91 static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst)
  92 {
  93         return rcu_dereference(dst->_neighbour);
  94 }
  95
  96 static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst)
  97 {
  98         return rcu_dereference_raw(dst->_neighbour);
  99 }
 100
 101 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
 102 {
 103         rcu_assign_pointer(dst->_neighbour, neigh);
 104 }
 105
 106 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 107 extern const u32 dst_default_metrics[RTAX_MAX];
 108
 109 #define DST_METRICS_READ_ONLY   0x1UL
 110 #define __DST_METRICS_PTR(Y)    \
 111         ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
 112 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 113
 114 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 115 {
 116         return dst->_metrics & DST_METRICS_READ_ONLY;
 117 }
 118
 119 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 120
 121 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 122 {
 123         unsigned long val = dst->_metrics;
 124         if (!(val & DST_METRICS_READ_ONLY))
 125                 __dst_destroy_metrics_generic(dst, val);
 126 }
 127
 128 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 129 {
 130         unsigned long p = dst->_metrics;
 131
 132         BUG_ON(!p);
 133
 134         if (p & DST_METRICS_READ_ONLY)
 135                 return dst->ops->cow_metrics(dst, p);
 136         return __DST_METRICS_PTR(p);
 137 }
 138
 139 /* This may only be invoked before the entry has reached global
 140  * visibility.
 141  */
 142 static inline void dst_init_metrics(struct dst_entry *dst,
 143                                     const u32 *src_metrics,
 144                                     bool read_only)
 145 {
 146         dst->_metrics = ((unsigned long) src_metrics) |
 147                 (read_only ? DST_METRICS_READ_ONLY : 0);
 148 }
 149
 150 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 151 {
 152         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 153
 154         if (dst_metrics) {
 155                 u32 *src_metrics = DST_METRICS_PTR(src);
 156
 157                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 158         }
 159 }
 160
 161 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 162 {
 163         return DST_METRICS_PTR(dst);
 164 }
 165
 166 static inline u32
 167 dst_metric_raw(const struct dst_entry *dst, const int metric)
 168 {
 169         u32 *p = DST_METRICS_PTR(dst);
 170
 171         return p[metric-1];
 172 }
 173
 174 static inline u32
 175 dst_metric(const struct dst_entry *dst, const int metric)
 176 {
 177         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 178                      metric == RTAX_ADVMSS ||
 179                      metric == RTAX_MTU);
 180         return dst_metric_raw(dst, metric);
 181 }
 182
 183 static inline u32
 184 dst_metric_advmss(const struct dst_entry *dst)
 185 {
 186         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 187
 188         if (!advmss)
 189                 advmss = dst->ops->default_advmss(dst);
 190
 191         return advmss;
 192 }
 193
 194 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 195 {
 196         u32 *p = dst_metrics_write_ptr(dst);
 197
 198         if (p)
 199                 p[metric-1] = val;
 200 }
 201
 202 static inline u32
 203 dst_feature(const struct dst_entry *dst, u32 feature)
 204 {
 205         return dst_metric(dst, RTAX_FEATURES) & feature;
 206 }
 207
 208 static inline u32 dst_mtu(const struct dst_entry *dst)
 209 {
 210         return dst->ops->mtu(dst);
 211 }
 212
 213 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 214 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 215 {
 216         return msecs_to_jiffies(dst_metric(dst, metric));
 217 }
 218
 219 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 220                                       unsigned long rtt)
 221 {
 222         dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
 223 }
 224
 225 static inline u32
 226 dst_allfrag(const struct dst_entry *dst)
 227 {
 228         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 229         return ret;
 230 }
 231
 232 static inline int
 233 dst_metric_locked(const struct dst_entry *dst, int metric)
 234 {
 235         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 236 }
 237
 238 static inline void dst_hold(struct dst_entry * dst)
 239 {
 240         /*
 241          * If your kernel compilation stops here, please check
 242          * __pad_to_align_refcnt declaration in struct dst_entry
 243          */
 244         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 245         atomic_inc(&dst->__refcnt);
 246 }
 247
 248 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 249 {
 250         dst_hold(dst);
 251         dst->__use++;
 252         dst->lastuse = time;
 253 }
 254
 255 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 256 {
 257         dst->__use++;
 258         dst->lastuse = time;
 259 }
 260
 261 static inline
 262 struct dst_entry * dst_clone(struct dst_entry * dst)
 263 {
 264         if (dst)
 265                 atomic_inc(&dst->__refcnt);
 266         return dst;
 267 }
 268
 269 extern void dst_release(struct dst_entry *dst);
 270
 271 static inline void refdst_drop(unsigned long refdst)
 272 {
 273         if (!(refdst & SKB_DST_NOREF))
 274                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 275 }
 276
 277 /**
 278  * skb_dst_drop - drops skb dst
 279  * @skb: buffer
 280  *
 281  * Drops dst reference count if a reference was taken.
 282  */
 283 static inline void skb_dst_drop(struct sk_buff *skb)
 284 {
 285         if (skb->_skb_refdst) {
 286                 refdst_drop(skb->_skb_refdst);
 287                 skb->_skb_refdst = 0UL;
 288         }
 289 }
 290
 291 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 292 {
 293         nskb->_skb_refdst = oskb->_skb_refdst;
 294         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 295                 dst_clone(skb_dst(nskb));
 296 }
 297
 298 /**
 299  * skb_dst_force - makes sure skb dst is refcounted
 300  * @skb: buffer
 301  *
 302  * If dst is not yet refcounted, let's do it
 303  */
 304 static inline void skb_dst_force(struct sk_buff *skb)
 305 {
 306         if (skb_dst_is_noref(skb)) {
 307                 WARN_ON(!rcu_read_lock_held());
 308                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 309                 dst_clone(skb_dst(skb));
 310         }
 311 }
 312
 313
 314 /**
 315  *      __skb_tunnel_rx - prepare skb for rx reinsert
 316  *      @skb: buffer
 317  *      @dev: tunnel device
 318  *
 319  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 320  *      so make some cleanups. (no accounting done)
 321  */
 322 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 323 {
 324         skb->dev = dev;
 325
 326         /*
 327          * Clear rxhash so that we can recalulate the hash for the
 328          * encapsulated packet, unless we have already determine the hash
 329          * over the L4 4-tuple.
 330          */
 331         if (!skb->l4_rxhash)
 332                 skb->rxhash = 0;
 333         skb_set_queue_mapping(skb, 0);
 334         skb_dst_drop(skb);
 335         nf_reset(skb);
 336 }
 337
 338 /**
 339  *      skb_tunnel_rx - prepare skb for rx reinsert
 340  *      @skb: buffer
 341  *      @dev: tunnel device
 342  *
 343  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 344  *      so make some cleanups, and perform accounting.
 345  *      Note: this accounting is not SMP safe.
 346  */
 347 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 348 {
 349         /* TODO : stats should be SMP safe */
 350         dev->stats.rx_packets++;
 351         dev->stats.rx_bytes += skb->len;
 352         __skb_tunnel_rx(skb, dev);
 353 }
 354
 355 /* Children define the path of the packet through the
 356  * Linux networking.  Thus, destinations are stackable.
 357  */
 358
 359 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 360 {
 361         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 362
 363         skb_dst_drop(skb);
 364         return child;
 365 }
 366
 367 extern int dst_discard(struct sk_buff *skb);
 368 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
 369                        int initial_ref, int initial_obsolete, int flags);
 370 extern void __dst_free(struct dst_entry * dst);
 371 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 372
 373 static inline void dst_free(struct dst_entry * dst)
 374 {
 375         if (dst->obsolete > 1)
 376                 return;
 377         if (!atomic_read(&dst->__refcnt)) {
 378                 dst = dst_destroy(dst);
 379                 if (!dst)
 380                         return;
 381         }
 382         __dst_free(dst);
 383 }
 384
 385 static inline void dst_rcu_free(struct rcu_head *head)
 386 {
 387         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 388         dst_free(dst);
 389 }
 390
 391 static inline void dst_confirm(struct dst_entry *dst)
 392 {
 393         if (dst) {
 394                 struct neighbour *n;
 395
 396                 rcu_read_lock();
 397                 n = dst_get_neighbour_noref(dst);
 398                 neigh_confirm(n);
 399                 rcu_read_unlock();
 400         }
 401 }
 402
 403 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 404 {
 405         return dst->ops->neigh_lookup(dst, daddr);
 406 }
 407
 408 static inline void dst_link_failure(struct sk_buff *skb)
 409 {
 410         struct dst_entry *dst = skb_dst(skb);
 411         if (dst && dst->ops && dst->ops->link_failure)
 412                 dst->ops->link_failure(skb);
 413 }
 414
 415 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 416 {
 417         unsigned long expires = jiffies + timeout;
 418
 419         if (expires == 0)
 420                 expires = 1;
 421
 422         if (dst->expires == 0 || time_before(expires, dst->expires))
 423                 dst->expires = expires;
 424 }
 425
 426 /* Output packet to network from transport.  */
 427 static inline int dst_output(struct sk_buff *skb)
 428 {
 429         return skb_dst(skb)->output(skb);
 430 }
 431
 432 /* Input packet from network to transport.  */
 433 static inline int dst_input(struct sk_buff *skb)
 434 {
 435         return skb_dst(skb)->input(skb);
 436 }
 437
 438 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 439 {
 440         if (dst->obsolete)
 441                 dst = dst->ops->check(dst, cookie);
 442         return dst;
 443 }
 444
 445 extern void             dst_init(void);
 446
 447 /* Flags for xfrm_lookup flags argument. */
 448 enum {
 449         XFRM_LOOKUP_ICMP = 1 << 0,
 450 };
 451
 452 struct flowi;
 453 #ifndef CONFIG_XFRM
 454 static inline struct dst_entry *xfrm_lookup(struct net *net,
 455                                             struct dst_entry *dst_orig,
 456                                             const struct flowi *fl, struct sock *sk,
 457                                             int flags)
 458 {
 459         return dst_orig;
 460 }
 461 #else
 462 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 463                                      const struct flowi *fl, struct sock *sk,
 464                                      int flags);
 465 #endif
 466
 467 #endif /* _NET_DST_H */