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 /*
  20  * 0 - no debugging messages
  21  * 1 - rare events and bugs (default)
  22  * 2 - trace mode.
  23  */
  24 #define RT_CACHE_DEBUG          0
  25
  26 #define DST_GC_MIN      (HZ/10)
  27 #define DST_GC_INC      (HZ/2)
  28 #define DST_GC_MAX      (120*HZ)
  29
  30 /* Each dst_entry has reference count and sits in some parent list(s).
  31  * When it is removed from parent list, it is "freed" (dst_free).
  32  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
  33  * is zero, it can be destroyed immediately, otherwise it is added
  34  * to gc list and garbage collector periodically checks the refcnt.
  35  */
  36
  37 struct sk_buff;
  38
  39 struct dst_entry {
  40         struct rcu_head         rcu_head;
  41         struct dst_entry        *child;
  42         struct net_device       *dev;
  43         short                   error;
  44         short                   obsolete;
  45         int                     flags;
  46 #define DST_HOST                0x0001
  47 #define DST_NOXFRM              0x0002
  48 #define DST_NOPOLICY            0x0004
  49 #define DST_NOHASH              0x0008
  50 #define DST_NOCACHE             0x0010
  51         unsigned long           expires;
  52
  53         unsigned short          header_len;     /* more space at head required */
  54         unsigned short          trailer_len;    /* space to reserve at tail */
  55
  56         unsigned int            rate_tokens;
  57         unsigned long           rate_last;      /* rate limiting for ICMP */
  58
  59         struct dst_entry        *path;
  60
  61         struct neighbour        *neighbour;
  62         struct hh_cache         *hh;
  63 #ifdef CONFIG_XFRM
  64         struct xfrm_state       *xfrm;
  65 #else
  66         void                    *__pad1;
  67 #endif
  68         int                     (*input)(struct sk_buff*);
  69         int                     (*output)(struct sk_buff*);
  70
  71         struct  dst_ops         *ops;
  72
  73         u32                     metrics[RTAX_MAX];
  74
  75 #ifdef CONFIG_NET_CLS_ROUTE
  76         __u32                   tclassid;
  77 #else
  78         __u32                   __pad2;
  79 #endif
  80
  81
  82         /*
  83          * Align __refcnt to a 64 bytes alignment
  84          * (L1_CACHE_SIZE would be too much)
  85          */
  86 #ifdef CONFIG_64BIT
  87         long                    __pad_to_align_refcnt[1];
  88 #endif
  89         /*
  90          * __refcnt wants to be on a different cache line from
  91          * input/output/ops or performance tanks badly
  92          */
  93         atomic_t                __refcnt;       /* client references    */
  94         int                     __use;
  95         unsigned long           lastuse;
  96         union {
  97                 struct dst_entry *next;
  98                 struct rtable __rcu *rt_next;
  99                 struct rt6_info   *rt6_next;
 100                 struct dn_route  *dn_next;
 101         };
 102 };
 103
 104 #ifdef __KERNEL__
 105
 106 static inline u32
 107 dst_metric(const struct dst_entry *dst, int metric)
 108 {
 109         return dst->metrics[metric-1];
 110 }
 111
 112 static inline u32
 113 dst_feature(const struct dst_entry *dst, u32 feature)
 114 {
 115         return dst_metric(dst, RTAX_FEATURES) & feature;
 116 }
 117
 118 static inline u32 dst_mtu(const struct dst_entry *dst)
 119 {
 120         u32 mtu = dst_metric(dst, RTAX_MTU);
 121         /*
 122          * Alexey put it here, so ask him about it :)
 123          */
 124         barrier();
 125         return mtu;
 126 }
 127
 128 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 129 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 130 {
 131         return msecs_to_jiffies(dst_metric(dst, metric));
 132 }
 133
 134 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 135                                       unsigned long rtt)
 136 {
 137         dst->metrics[metric-1] = jiffies_to_msecs(rtt);
 138 }
 139
 140 static inline u32
 141 dst_allfrag(const struct dst_entry *dst)
 142 {
 143         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 144         /* Yes, _exactly_. This is paranoia. */
 145         barrier();
 146         return ret;
 147 }
 148
 149 static inline int
 150 dst_metric_locked(struct dst_entry *dst, int metric)
 151 {
 152         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 153 }
 154
 155 static inline void dst_hold(struct dst_entry * dst)
 156 {
 157         /*
 158          * If your kernel compilation stops here, please check
 159          * __pad_to_align_refcnt declaration in struct dst_entry
 160          */
 161         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 162         atomic_inc(&dst->__refcnt);
 163 }
 164
 165 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 166 {
 167         dst_hold(dst);
 168         dst->__use++;
 169         dst->lastuse = time;
 170 }
 171
 172 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 173 {
 174         dst->__use++;
 175         dst->lastuse = time;
 176 }
 177
 178 static inline
 179 struct dst_entry * dst_clone(struct dst_entry * dst)
 180 {
 181         if (dst)
 182                 atomic_inc(&dst->__refcnt);
 183         return dst;
 184 }
 185
 186 extern void dst_release(struct dst_entry *dst);
 187
 188 static inline void refdst_drop(unsigned long refdst)
 189 {
 190         if (!(refdst & SKB_DST_NOREF))
 191                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 192 }
 193
 194 /**
 195  * skb_dst_drop - drops skb dst
 196  * @skb: buffer
 197  *
 198  * Drops dst reference count if a reference was taken.
 199  */
 200 static inline void skb_dst_drop(struct sk_buff *skb)
 201 {
 202         if (skb->_skb_refdst) {
 203                 refdst_drop(skb->_skb_refdst);
 204                 skb->_skb_refdst = 0UL;
 205         }
 206 }
 207
 208 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 209 {
 210         nskb->_skb_refdst = oskb->_skb_refdst;
 211         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 212                 dst_clone(skb_dst(nskb));
 213 }
 214
 215 /**
 216  * skb_dst_force - makes sure skb dst is refcounted
 217  * @skb: buffer
 218  *
 219  * If dst is not yet refcounted, let's do it
 220  */
 221 static inline void skb_dst_force(struct sk_buff *skb)
 222 {
 223         if (skb_dst_is_noref(skb)) {
 224                 WARN_ON(!rcu_read_lock_held());
 225                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 226                 dst_clone(skb_dst(skb));
 227         }
 228 }
 229
 230
 231 /**
 232  *      __skb_tunnel_rx - prepare skb for rx reinsert
 233  *      @skb: buffer
 234  *      @dev: tunnel device
 235  *
 236  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 237  *      so make some cleanups. (no accounting done)
 238  */
 239 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 240 {
 241         skb->dev = dev;
 242         skb->rxhash = 0;
 243         skb_set_queue_mapping(skb, 0);
 244         skb_dst_drop(skb);
 245         nf_reset(skb);
 246 }
 247
 248 /**
 249  *      skb_tunnel_rx - prepare skb for rx reinsert
 250  *      @skb: buffer
 251  *      @dev: tunnel device
 252  *
 253  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 254  *      so make some cleanups, and perform accounting.
 255  *      Note: this accounting is not SMP safe.
 256  */
 257 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 258 {
 259         /* TODO : stats should be SMP safe */
 260         dev->stats.rx_packets++;
 261         dev->stats.rx_bytes += skb->len;
 262         __skb_tunnel_rx(skb, dev);
 263 }
 264
 265 /* Children define the path of the packet through the
 266  * Linux networking.  Thus, destinations are stackable.
 267  */
 268
 269 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 270 {
 271         struct dst_entry *child = skb_dst(skb)->child;
 272
 273         skb_dst_drop(skb);
 274         return child;
 275 }
 276
 277 extern int dst_discard(struct sk_buff *skb);
 278 extern void * dst_alloc(struct dst_ops * ops);
 279 extern void __dst_free(struct dst_entry * dst);
 280 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 281
 282 static inline void dst_free(struct dst_entry * dst)
 283 {
 284         if (dst->obsolete > 1)
 285                 return;
 286         if (!atomic_read(&dst->__refcnt)) {
 287                 dst = dst_destroy(dst);
 288                 if (!dst)
 289                         return;
 290         }
 291         __dst_free(dst);
 292 }
 293
 294 static inline void dst_rcu_free(struct rcu_head *head)
 295 {
 296         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 297         dst_free(dst);
 298 }
 299
 300 static inline void dst_confirm(struct dst_entry *dst)
 301 {
 302         if (dst)
 303                 neigh_confirm(dst->neighbour);
 304 }
 305
 306 static inline void dst_link_failure(struct sk_buff *skb)
 307 {
 308         struct dst_entry *dst = skb_dst(skb);
 309         if (dst && dst->ops && dst->ops->link_failure)
 310                 dst->ops->link_failure(skb);
 311 }
 312
 313 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 314 {
 315         unsigned long expires = jiffies + timeout;
 316
 317         if (expires == 0)
 318                 expires = 1;
 319
 320         if (dst->expires == 0 || time_before(expires, dst->expires))
 321                 dst->expires = expires;
 322 }
 323
 324 /* Output packet to network from transport.  */
 325 static inline int dst_output(struct sk_buff *skb)
 326 {
 327         return skb_dst(skb)->output(skb);
 328 }
 329
 330 /* Input packet from network to transport.  */
 331 static inline int dst_input(struct sk_buff *skb)
 332 {
 333         return skb_dst(skb)->input(skb);
 334 }
 335
 336 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 337 {
 338         if (dst->obsolete)
 339                 dst = dst->ops->check(dst, cookie);
 340         return dst;
 341 }
 342
 343 extern void             dst_init(void);
 344
 345 /* Flags for xfrm_lookup flags argument. */
 346 enum {
 347         XFRM_LOOKUP_WAIT = 1 << 0,
 348         XFRM_LOOKUP_ICMP = 1 << 1,
 349 };
 350
 351 struct flowi;
 352 #ifndef CONFIG_XFRM
 353 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 354                               struct flowi *fl, struct sock *sk, int flags)
 355 {
 356         return 0;
 357 }
 358 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 359                                 struct flowi *fl, struct sock *sk, int flags)
 360 {
 361         return 0;
 362 }
 363 #else
 364 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 365                        struct flowi *fl, struct sock *sk, int flags);
 366 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 367                          struct flowi *fl, struct sock *sk, int flags);
 368 #endif
 369 #endif
 370
 371 #endif /* _NET_DST_H */