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 <linux/netdevice.h>
  12 #include <linux/rtnetlink.h>
  13 #include <linux/rcupdate.h>
  14 #include <linux/jiffies.h>
  15 #include <net/neighbour.h>
  16 #include <asm/processor.h>
  17
  18 /*
  19  * 0 - no debugging messages
  20  * 1 - rare events and bugs (default)
  21  * 2 - trace mode.
  22  */
  23 #define RT_CACHE_DEBUG          0
  24
  25 #define DST_GC_MIN      (HZ/10)
  26 #define DST_GC_INC      (HZ/2)
  27 #define DST_GC_MAX      (120*HZ)
  28
  29 /* Each dst_entry has reference count and sits in some parent list(s).
  30  * When it is removed from parent list, it is "freed" (dst_free).
  31  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
  32  * is zero, it can be destroyed immediately, otherwise it is added
  33  * to gc list and garbage collector periodically checks the refcnt.
  34  */
  35
  36 struct sk_buff;
  37
  38 struct dst_entry
  39 {
  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                1
  47 #define DST_NOXFRM              2
  48 #define DST_NOPOLICY            4
  49 #define DST_NOHASH              8
  50         unsigned long           expires;
  51
  52         unsigned short          header_len;     /* more space at head required */
  53         unsigned short          nfheader_len;   /* more non-fragment space at head required */
  54         unsigned short          trailer_len;    /* space to reserve at tail */
  55
  56         u32                     metrics[RTAX_MAX];
  57         struct dst_entry        *path;
  58
  59         unsigned long           rate_last;      /* rate limiting for ICMP */
  60         unsigned long           rate_tokens;
  61
  62         struct neighbour        *neighbour;
  63         struct hh_cache         *hh;
  64         struct xfrm_state       *xfrm;
  65
  66         int                     (*input)(struct sk_buff*);
  67         int                     (*output)(struct sk_buff*);
  68
  69 #ifdef CONFIG_NET_CLS_ROUTE
  70         __u32                   tclassid;
  71 #endif
  72
  73         struct  dst_ops         *ops;
  74
  75         unsigned long           lastuse;
  76         atomic_t                __refcnt;       /* client references    */
  77         int                     __use;
  78         union {
  79                 struct dst_entry *next;
  80                 struct rtable    *rt_next;
  81                 struct rt6_info   *rt6_next;
  82                 struct dn_route  *dn_next;
  83         };
  84         char                    info[0];
  85 };
  86
  87
  88 struct dst_ops
  89 {
  90         unsigned short          family;
  91         __be16                  protocol;
  92         unsigned                gc_thresh;
  93
  94         int                     (*gc)(void);
  95         struct dst_entry *      (*check)(struct dst_entry *, __u32 cookie);
  96         void                    (*destroy)(struct dst_entry *);
  97         void                    (*ifdown)(struct dst_entry *,
  98                                           struct net_device *dev, int how);
  99         struct dst_entry *      (*negative_advice)(struct dst_entry *);
 100         void                    (*link_failure)(struct sk_buff *);
 101         void                    (*update_pmtu)(struct dst_entry *dst, u32 mtu);
 102         int                     entry_size;
 103
 104         atomic_t                entries;
 105         struct kmem_cache               *kmem_cachep;
 106 };
 107
 108 #ifdef __KERNEL__
 109
 110 static inline u32
 111 dst_metric(const struct dst_entry *dst, int metric)
 112 {
 113         return dst->metrics[metric-1];
 114 }
 115
 116 static inline u32 dst_mtu(const struct dst_entry *dst)
 117 {
 118         u32 mtu = dst_metric(dst, RTAX_MTU);
 119         /*
 120          * Alexey put it here, so ask him about it :)
 121          */
 122         barrier();
 123         return mtu;
 124 }
 125
 126 static inline u32
 127 dst_allfrag(const struct dst_entry *dst)
 128 {
 129         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 130         /* Yes, _exactly_. This is paranoia. */
 131         barrier();
 132         return ret;
 133 }
 134
 135 static inline int
 136 dst_metric_locked(struct dst_entry *dst, int metric)
 137 {
 138         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 139 }
 140
 141 static inline void dst_hold(struct dst_entry * dst)
 142 {
 143         atomic_inc(&dst->__refcnt);
 144 }
 145
 146 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 147 {
 148         dst_hold(dst);
 149         dst->__use++;
 150         dst->lastuse = time;
 151 }
 152
 153 static inline
 154 struct dst_entry * dst_clone(struct dst_entry * dst)
 155 {
 156         if (dst)
 157                 atomic_inc(&dst->__refcnt);
 158         return dst;
 159 }
 160
 161 static inline
 162 void dst_release(struct dst_entry * dst)
 163 {
 164         if (dst) {
 165                 WARN_ON(atomic_read(&dst->__refcnt) < 1);
 166                 smp_mb__before_atomic_dec();
 167                 atomic_dec(&dst->__refcnt);
 168         }
 169 }
 170
 171 /* Children define the path of the packet through the
 172  * Linux networking.  Thus, destinations are stackable.
 173  */
 174
 175 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 176 {
 177         struct dst_entry *child = dst_clone(dst->child);
 178
 179         dst_release(dst);
 180         return child;
 181 }
 182
 183 extern void * dst_alloc(struct dst_ops * ops);
 184 extern void __dst_free(struct dst_entry * dst);
 185 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 186
 187 static inline void dst_free(struct dst_entry * dst)
 188 {
 189         if (dst->obsolete > 1)
 190                 return;
 191         if (!atomic_read(&dst->__refcnt)) {
 192                 dst = dst_destroy(dst);
 193                 if (!dst)
 194                         return;
 195         }
 196         __dst_free(dst);
 197 }
 198
 199 static inline void dst_rcu_free(struct rcu_head *head)
 200 {
 201         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 202         dst_free(dst);
 203 }
 204
 205 static inline void dst_confirm(struct dst_entry *dst)
 206 {
 207         if (dst)
 208                 neigh_confirm(dst->neighbour);
 209 }
 210
 211 static inline void dst_negative_advice(struct dst_entry **dst_p)
 212 {
 213         struct dst_entry * dst = *dst_p;
 214         if (dst && dst->ops->negative_advice)
 215                 *dst_p = dst->ops->negative_advice(dst);
 216 }
 217
 218 static inline void dst_link_failure(struct sk_buff *skb)
 219 {
 220         struct dst_entry * dst = skb->dst;
 221         if (dst && dst->ops && dst->ops->link_failure)
 222                 dst->ops->link_failure(skb);
 223 }
 224
 225 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 226 {
 227         unsigned long expires = jiffies + timeout;
 228
 229         if (expires == 0)
 230                 expires = 1;
 231
 232         if (dst->expires == 0 || time_before(expires, dst->expires))
 233                 dst->expires = expires;
 234 }
 235
 236 /* Output packet to network from transport.  */
 237 static inline int dst_output(struct sk_buff *skb)
 238 {
 239         return skb->dst->output(skb);
 240 }
 241
 242 /* Input packet from network to transport.  */
 243 static inline int dst_input(struct sk_buff *skb)
 244 {
 245         int err;
 246
 247         for (;;) {
 248                 err = skb->dst->input(skb);
 249
 250                 if (likely(err == 0))
 251                         return err;
 252                 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
 253                 if (unlikely(err != NET_XMIT_BYPASS))
 254                         return err;
 255         }
 256 }
 257
 258 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 259 {
 260         if (dst->obsolete)
 261                 dst = dst->ops->check(dst, cookie);
 262         return dst;
 263 }
 264
 265 extern void             dst_init(void);
 266
 267 struct flowi;
 268 #ifndef CONFIG_XFRM
 269 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 270                        struct sock *sk, int flags)
 271 {
 272         return 0;
 273 }
 274 static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 275                                 struct sock *sk, int flags)
 276 {
 277         return 0;
 278 }
 279 #else
 280 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 281                        struct sock *sk, int flags);
 282 extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 283                          struct sock *sk, int flags);
 284 #endif
 285 #endif
 286
 287 #endif /* _NET_DST_H */