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
  63         short                   error;
  64         short                   obsolete;
  65         unsigned short          header_len;     /* more space at head required */
  66         unsigned short          trailer_len;    /* space to reserve at tail */
  67 #ifdef CONFIG_IP_ROUTE_CLASSID
  68         __u32                   tclassid;
  69 #else
  70         __u32                   __pad2;
  71 #endif
  72
  73         /*
  74          * Align __refcnt to a 64 bytes alignment
  75          * (L1_CACHE_SIZE would be too much)
  76          */
  77 #ifdef CONFIG_64BIT
  78         long                    __pad_to_align_refcnt[2];
  79 #endif
  80         /*
  81          * __refcnt wants to be on a different cache line from
  82          * input/output/ops or performance tanks badly
  83          */
  84         atomic_t                __refcnt;       /* client references    */
  85         int                     __use;
  86         unsigned long           lastuse;
  87         union {
  88                 struct dst_entry        *next;
  89                 struct rtable __rcu     *rt_next;
  90                 struct rt6_info         *rt6_next;
  91                 struct dn_route __rcu   *dn_next;
  92         };
  93 };
  94
  95 static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst)
  96 {
  97         return rcu_dereference(dst->_neighbour);
  98 }
  99
 100 static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst)
 101 {
 102         return rcu_dereference_raw(dst->_neighbour);
 103 }
 104
 105 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh)
 106 {
 107         rcu_assign_pointer(dst->_neighbour, neigh);
 108 }
 109
 110 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 111 extern const u32 dst_default_metrics[RTAX_MAX];
 112
 113 #define DST_METRICS_READ_ONLY   0x1UL
 114 #define __DST_METRICS_PTR(Y)    \
 115         ((u32 *)((Y) & ~DST_METRICS_READ_ONLY))
 116 #define DST_METRICS_PTR(X)      __DST_METRICS_PTR((X)->_metrics)
 117
 118 static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 119 {
 120         return dst->_metrics & DST_METRICS_READ_ONLY;
 121 }
 122
 123 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 124
 125 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
 126 {
 127         unsigned long val = dst->_metrics;
 128         if (!(val & DST_METRICS_READ_ONLY))
 129                 __dst_destroy_metrics_generic(dst, val);
 130 }
 131
 132 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
 133 {
 134         unsigned long p = dst->_metrics;
 135
 136         BUG_ON(!p);
 137
 138         if (p & DST_METRICS_READ_ONLY)
 139                 return dst->ops->cow_metrics(dst, p);
 140         return __DST_METRICS_PTR(p);
 141 }
 142
 143 /* This may only be invoked before the entry has reached global
 144  * visibility.
 145  */
 146 static inline void dst_init_metrics(struct dst_entry *dst,
 147                                     const u32 *src_metrics,
 148                                     bool read_only)
 149 {
 150         dst->_metrics = ((unsigned long) src_metrics) |
 151                 (read_only ? DST_METRICS_READ_ONLY : 0);
 152 }
 153
 154 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 155 {
 156         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 157
 158         if (dst_metrics) {
 159                 u32 *src_metrics = DST_METRICS_PTR(src);
 160
 161                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 162         }
 163 }
 164
 165 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 166 {
 167         return DST_METRICS_PTR(dst);
 168 }
 169
 170 static inline u32
 171 dst_metric_raw(const struct dst_entry *dst, const int metric)
 172 {
 173         u32 *p = DST_METRICS_PTR(dst);
 174
 175         return p[metric-1];
 176 }
 177
 178 static inline u32
 179 dst_metric(const struct dst_entry *dst, const int metric)
 180 {
 181         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 182                      metric == RTAX_ADVMSS ||
 183                      metric == RTAX_MTU);
 184         return dst_metric_raw(dst, metric);
 185 }
 186
 187 static inline u32
 188 dst_metric_advmss(const struct dst_entry *dst)
 189 {
 190         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 191
 192         if (!advmss)
 193                 advmss = dst->ops->default_advmss(dst);
 194
 195         return advmss;
 196 }
 197
 198 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 199 {
 200         u32 *p = dst_metrics_write_ptr(dst);
 201
 202         if (p)
 203                 p[metric-1] = val;
 204 }
 205
 206 static inline u32
 207 dst_feature(const struct dst_entry *dst, u32 feature)
 208 {
 209         return dst_metric(dst, RTAX_FEATURES) & feature;
 210 }
 211
 212 static inline u32 dst_mtu(const struct dst_entry *dst)
 213 {
 214         return dst->ops->mtu(dst);
 215 }
 216
 217 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 218 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 219 {
 220         return msecs_to_jiffies(dst_metric(dst, metric));
 221 }
 222
 223 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 224                                       unsigned long rtt)
 225 {
 226         dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
 227 }
 228
 229 static inline u32
 230 dst_allfrag(const struct dst_entry *dst)
 231 {
 232         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 233         return ret;
 234 }
 235
 236 static inline int
 237 dst_metric_locked(const struct dst_entry *dst, int metric)
 238 {
 239         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 240 }
 241
 242 static inline void dst_hold(struct dst_entry * dst)
 243 {
 244         /*
 245          * If your kernel compilation stops here, please check
 246          * __pad_to_align_refcnt declaration in struct dst_entry
 247          */
 248         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 249         atomic_inc(&dst->__refcnt);
 250 }
 251
 252 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 253 {
 254         dst_hold(dst);
 255         dst->__use++;
 256         dst->lastuse = time;
 257 }
 258
 259 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 260 {
 261         dst->__use++;
 262         dst->lastuse = time;
 263 }
 264
 265 static inline
 266 struct dst_entry * dst_clone(struct dst_entry * dst)
 267 {
 268         if (dst)
 269                 atomic_inc(&dst->__refcnt);
 270         return dst;
 271 }
 272
 273 extern void dst_release(struct dst_entry *dst);
 274
 275 static inline void refdst_drop(unsigned long refdst)
 276 {
 277         if (!(refdst & SKB_DST_NOREF))
 278                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 279 }
 280
 281 /**
 282  * skb_dst_drop - drops skb dst
 283  * @skb: buffer
 284  *
 285  * Drops dst reference count if a reference was taken.
 286  */
 287 static inline void skb_dst_drop(struct sk_buff *skb)
 288 {
 289         if (skb->_skb_refdst) {
 290                 refdst_drop(skb->_skb_refdst);
 291                 skb->_skb_refdst = 0UL;
 292         }
 293 }
 294
 295 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 296 {
 297         nskb->_skb_refdst = oskb->_skb_refdst;
 298         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 299                 dst_clone(skb_dst(nskb));
 300 }
 301
 302 /**
 303  * skb_dst_force - makes sure skb dst is refcounted
 304  * @skb: buffer
 305  *
 306  * If dst is not yet refcounted, let's do it
 307  */
 308 static inline void skb_dst_force(struct sk_buff *skb)
 309 {
 310         if (skb_dst_is_noref(skb)) {
 311                 WARN_ON(!rcu_read_lock_held());
 312                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 313                 dst_clone(skb_dst(skb));
 314         }
 315 }
 316
 317
 318 /**
 319  *      __skb_tunnel_rx - prepare skb for rx reinsert
 320  *      @skb: buffer
 321  *      @dev: tunnel device
 322  *
 323  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 324  *      so make some cleanups. (no accounting done)
 325  */
 326 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 327 {
 328         skb->dev = dev;
 329
 330         /*
 331          * Clear rxhash so that we can recalulate the hash for the
 332          * encapsulated packet, unless we have already determine the hash
 333          * over the L4 4-tuple.
 334          */
 335         if (!skb->l4_rxhash)
 336                 skb->rxhash = 0;
 337         skb_set_queue_mapping(skb, 0);
 338         skb_dst_drop(skb);
 339         nf_reset(skb);
 340 }
 341
 342 /**
 343  *      skb_tunnel_rx - prepare skb for rx reinsert
 344  *      @skb: buffer
 345  *      @dev: tunnel device
 346  *
 347  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 348  *      so make some cleanups, and perform accounting.
 349  *      Note: this accounting is not SMP safe.
 350  */
 351 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 352 {
 353         /* TODO : stats should be SMP safe */
 354         dev->stats.rx_packets++;
 355         dev->stats.rx_bytes += skb->len;
 356         __skb_tunnel_rx(skb, dev);
 357 }
 358
 359 /* Children define the path of the packet through the
 360  * Linux networking.  Thus, destinations are stackable.
 361  */
 362
 363 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 364 {
 365         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 366
 367         skb_dst_drop(skb);
 368         return child;
 369 }
 370
 371 extern int dst_discard(struct sk_buff *skb);
 372 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
 373                        int initial_ref, int initial_obsolete, int flags);
 374 extern void __dst_free(struct dst_entry * dst);
 375 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 376
 377 static inline void dst_free(struct dst_entry * dst)
 378 {
 379         if (dst->obsolete > 1)
 380                 return;
 381         if (!atomic_read(&dst->__refcnt)) {
 382                 dst = dst_destroy(dst);
 383                 if (!dst)
 384                         return;
 385         }
 386         __dst_free(dst);
 387 }
 388
 389 static inline void dst_rcu_free(struct rcu_head *head)
 390 {
 391         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 392         dst_free(dst);
 393 }
 394
 395 static inline void dst_confirm(struct dst_entry *dst)
 396 {
 397         if (dst) {
 398                 struct neighbour *n;
 399
 400                 rcu_read_lock();
 401                 n = dst_get_neighbour_noref(dst);
 402                 neigh_confirm(n);
 403                 rcu_read_unlock();
 404         }
 405 }
 406
 407 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 408 {
 409         return dst->ops->neigh_lookup(dst, daddr);
 410 }
 411
 412 static inline void dst_link_failure(struct sk_buff *skb)
 413 {
 414         struct dst_entry *dst = skb_dst(skb);
 415         if (dst && dst->ops && dst->ops->link_failure)
 416                 dst->ops->link_failure(skb);
 417 }
 418
 419 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 420 {
 421         unsigned long expires = jiffies + timeout;
 422
 423         if (expires == 0)
 424                 expires = 1;
 425
 426         if (dst->expires == 0 || time_before(expires, dst->expires))
 427                 dst->expires = expires;
 428 }
 429
 430 /* Output packet to network from transport.  */
 431 static inline int dst_output(struct sk_buff *skb)
 432 {
 433         return skb_dst(skb)->output(skb);
 434 }
 435
 436 /* Input packet from network to transport.  */
 437 static inline int dst_input(struct sk_buff *skb)
 438 {
 439         return skb_dst(skb)->input(skb);
 440 }
 441
 442 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 443 {
 444         if (dst->obsolete)
 445                 dst = dst->ops->check(dst, cookie);
 446         return dst;
 447 }
 448
 449 extern void             dst_init(void);
 450
 451 /* Flags for xfrm_lookup flags argument. */
 452 enum {
 453         XFRM_LOOKUP_ICMP = 1 << 0,
 454 };
 455
 456 struct flowi;
 457 #ifndef CONFIG_XFRM
 458 static inline struct dst_entry *xfrm_lookup(struct net *net,
 459                                             struct dst_entry *dst_orig,
 460                                             const struct flowi *fl, struct sock *sk,
 461                                             int flags)
 462 {
 463         return dst_orig;
 464 }
 465 #else
 466 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 467                                      const struct flowi *fl, struct sock *sk,
 468                                      int flags);
 469 #endif
 470
 471 #endif /* _NET_DST_H */