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         if (p & DST_METRICS_READ_ONLY)
 115                 return dst->ops->cow_metrics(dst, p);
 116         return __DST_METRICS_PTR(p);
 117 }
 118
 119 /* This may only be invoked before the entry has reached global
 120  * visibility.
 121  */
 122 static inline void dst_init_metrics(struct dst_entry *dst,
 123                                     const u32 *src_metrics,
 124                                     bool read_only)
 125 {
 126         dst->_metrics = ((unsigned long) src_metrics) |
 127                 (read_only ? DST_METRICS_READ_ONLY : 0);
 128 }
 129
 130 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
 131 {
 132         u32 *dst_metrics = dst_metrics_write_ptr(dest);
 133
 134         if (dst_metrics) {
 135                 u32 *src_metrics = DST_METRICS_PTR(src);
 136
 137                 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
 138         }
 139 }
 140
 141 static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
 142 {
 143         return DST_METRICS_PTR(dst);
 144 }
 145
 146 static inline u32
 147 dst_metric_raw(const struct dst_entry *dst, const int metric)
 148 {
 149         u32 *p = DST_METRICS_PTR(dst);
 150
 151         return p[metric-1];
 152 }
 153
 154 static inline u32
 155 dst_metric(const struct dst_entry *dst, const int metric)
 156 {
 157         WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
 158                      metric == RTAX_ADVMSS ||
 159                      metric == RTAX_MTU);
 160         return dst_metric_raw(dst, metric);
 161 }
 162
 163 static inline u32
 164 dst_metric_advmss(const struct dst_entry *dst)
 165 {
 166         u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
 167
 168         if (!advmss)
 169                 advmss = dst->ops->default_advmss(dst);
 170
 171         return advmss;
 172 }
 173
 174 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
 175 {
 176         u32 *p = dst_metrics_write_ptr(dst);
 177
 178         if (p)
 179                 p[metric-1] = val;
 180 }
 181
 182 static inline u32
 183 dst_feature(const struct dst_entry *dst, u32 feature)
 184 {
 185         return dst_metric(dst, RTAX_FEATURES) & feature;
 186 }
 187
 188 static inline u32 dst_mtu(const struct dst_entry *dst)
 189 {
 190         u32 mtu = dst_metric_raw(dst, RTAX_MTU);
 191
 192         if (!mtu)
 193                 mtu = dst->ops->default_mtu(dst);
 194
 195         return mtu;
 196 }
 197
 198 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 199 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 200 {
 201         return msecs_to_jiffies(dst_metric(dst, metric));
 202 }
 203
 204 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 205                                       unsigned long rtt)
 206 {
 207         dst_metric_set(dst, metric, jiffies_to_msecs(rtt));
 208 }
 209
 210 static inline u32
 211 dst_allfrag(const struct dst_entry *dst)
 212 {
 213         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 214         return ret;
 215 }
 216
 217 static inline int
 218 dst_metric_locked(const struct dst_entry *dst, int metric)
 219 {
 220         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 221 }
 222
 223 static inline void dst_hold(struct dst_entry * dst)
 224 {
 225         /*
 226          * If your kernel compilation stops here, please check
 227          * __pad_to_align_refcnt declaration in struct dst_entry
 228          */
 229         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 230         atomic_inc(&dst->__refcnt);
 231 }
 232
 233 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 234 {
 235         dst_hold(dst);
 236         dst->__use++;
 237         dst->lastuse = time;
 238 }
 239
 240 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 241 {
 242         dst->__use++;
 243         dst->lastuse = time;
 244 }
 245
 246 static inline
 247 struct dst_entry * dst_clone(struct dst_entry * dst)
 248 {
 249         if (dst)
 250                 atomic_inc(&dst->__refcnt);
 251         return dst;
 252 }
 253
 254 extern void dst_release(struct dst_entry *dst);
 255
 256 static inline void refdst_drop(unsigned long refdst)
 257 {
 258         if (!(refdst & SKB_DST_NOREF))
 259                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 260 }
 261
 262 /**
 263  * skb_dst_drop - drops skb dst
 264  * @skb: buffer
 265  *
 266  * Drops dst reference count if a reference was taken.
 267  */
 268 static inline void skb_dst_drop(struct sk_buff *skb)
 269 {
 270         if (skb->_skb_refdst) {
 271                 refdst_drop(skb->_skb_refdst);
 272                 skb->_skb_refdst = 0UL;
 273         }
 274 }
 275
 276 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 277 {
 278         nskb->_skb_refdst = oskb->_skb_refdst;
 279         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 280                 dst_clone(skb_dst(nskb));
 281 }
 282
 283 /**
 284  * skb_dst_force - makes sure skb dst is refcounted
 285  * @skb: buffer
 286  *
 287  * If dst is not yet refcounted, let's do it
 288  */
 289 static inline void skb_dst_force(struct sk_buff *skb)
 290 {
 291         if (skb_dst_is_noref(skb)) {
 292                 WARN_ON(!rcu_read_lock_held());
 293                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 294                 dst_clone(skb_dst(skb));
 295         }
 296 }
 297
 298
 299 /**
 300  *      __skb_tunnel_rx - prepare skb for rx reinsert
 301  *      @skb: buffer
 302  *      @dev: tunnel device
 303  *
 304  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 305  *      so make some cleanups. (no accounting done)
 306  */
 307 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 308 {
 309         skb->dev = dev;
 310         skb->rxhash = 0;
 311         skb_set_queue_mapping(skb, 0);
 312         skb_dst_drop(skb);
 313         nf_reset(skb);
 314 }
 315
 316 /**
 317  *      skb_tunnel_rx - prepare skb for rx reinsert
 318  *      @skb: buffer
 319  *      @dev: tunnel device
 320  *
 321  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 322  *      so make some cleanups, and perform accounting.
 323  *      Note: this accounting is not SMP safe.
 324  */
 325 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 326 {
 327         /* TODO : stats should be SMP safe */
 328         dev->stats.rx_packets++;
 329         dev->stats.rx_bytes += skb->len;
 330         __skb_tunnel_rx(skb, dev);
 331 }
 332
 333 /* Children define the path of the packet through the
 334  * Linux networking.  Thus, destinations are stackable.
 335  */
 336
 337 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 338 {
 339         struct dst_entry *child = dst_clone(skb_dst(skb)->child);
 340
 341         skb_dst_drop(skb);
 342         return child;
 343 }
 344
 345 extern int dst_discard(struct sk_buff *skb);
 346 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev,
 347                        int initial_ref, int initial_obsolete, int flags);
 348 extern void __dst_free(struct dst_entry * dst);
 349 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 350
 351 static inline void dst_free(struct dst_entry * dst)
 352 {
 353         if (dst->obsolete > 1)
 354                 return;
 355         if (!atomic_read(&dst->__refcnt)) {
 356                 dst = dst_destroy(dst);
 357                 if (!dst)
 358                         return;
 359         }
 360         __dst_free(dst);
 361 }
 362
 363 static inline void dst_rcu_free(struct rcu_head *head)
 364 {
 365         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 366         dst_free(dst);
 367 }
 368
 369 static inline void dst_confirm(struct dst_entry *dst)
 370 {
 371         if (dst)
 372                 neigh_confirm(dst->neighbour);
 373 }
 374
 375 static inline void dst_link_failure(struct sk_buff *skb)
 376 {
 377         struct dst_entry *dst = skb_dst(skb);
 378         if (dst && dst->ops && dst->ops->link_failure)
 379                 dst->ops->link_failure(skb);
 380 }
 381
 382 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 383 {
 384         unsigned long expires = jiffies + timeout;
 385
 386         if (expires == 0)
 387                 expires = 1;
 388
 389         if (dst->expires == 0 || time_before(expires, dst->expires))
 390                 dst->expires = expires;
 391 }
 392
 393 /* Output packet to network from transport.  */
 394 static inline int dst_output(struct sk_buff *skb)
 395 {
 396         return skb_dst(skb)->output(skb);
 397 }
 398
 399 /* Input packet from network to transport.  */
 400 static inline int dst_input(struct sk_buff *skb)
 401 {
 402         return skb_dst(skb)->input(skb);
 403 }
 404
 405 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 406 {
 407         if (dst->obsolete)
 408                 dst = dst->ops->check(dst, cookie);
 409         return dst;
 410 }
 411
 412 extern void             dst_init(void);
 413
 414 /* Flags for xfrm_lookup flags argument. */
 415 enum {
 416         XFRM_LOOKUP_ICMP = 1 << 0,
 417 };
 418
 419 struct flowi;
 420 #ifndef CONFIG_XFRM
 421 static inline struct dst_entry *xfrm_lookup(struct net *net,
 422                                             struct dst_entry *dst_orig,
 423                                             const struct flowi *fl, struct sock *sk,
 424                                             int flags)
 425 {
 426         return dst_orig;
 427 }
 428 #else
 429 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
 430                                      const struct flowi *fl, struct sock *sk,
 431                                      int flags);
 432 #endif
 433
 434 #endif /* _NET_DST_H */