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