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/config.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 dst_entry        *next;
  41         atomic_t                __refcnt;       /* client references    */
  42         int                     __use;
  43         struct dst_entry        *child;
  44         struct net_device       *dev;
  45         short                   error;
  46         short                   obsolete;
  47         int                     flags;
  48 #define DST_HOST                1
  49 #define DST_NOXFRM              2
  50 #define DST_NOPOLICY            4
  51 #define DST_NOHASH              8
  52 #define DST_BALANCED            0x10
  53         unsigned long           lastuse;
  54         unsigned long           expires;
  55
  56         unsigned short          header_len;     /* more space at head required */
  57         unsigned short          trailer_len;    /* space to reserve at tail */
  58
  59         u32                     metrics[RTAX_MAX];
  60         struct dst_entry        *path;
  61
  62         unsigned long           rate_last;      /* rate limiting for ICMP */
  63         unsigned long           rate_tokens;
  64
  65         struct neighbour        *neighbour;
  66         struct hh_cache         *hh;
  67         struct xfrm_state       *xfrm;
  68
  69         int                     (*input)(struct sk_buff*);
  70         int                     (*output)(struct sk_buff*);
  71
  72 #ifdef CONFIG_NET_CLS_ROUTE
  73         __u32                   tclassid;
  74 #endif
  75
  76         struct  dst_ops         *ops;
  77         struct rcu_head         rcu_head;
  78
  79         char                    info[0];
  80 };
  81
  82
  83 struct dst_ops
  84 {
  85         unsigned short          family;
  86         unsigned short          protocol;
  87         unsigned                gc_thresh;
  88
  89         int                     (*gc)(void);
  90         struct dst_entry *      (*check)(struct dst_entry *, __u32 cookie);
  91         void                    (*destroy)(struct dst_entry *);
  92         void                    (*ifdown)(struct dst_entry *,
  93                                           struct net_device *dev, int how);
  94         struct dst_entry *      (*negative_advice)(struct dst_entry *);
  95         void                    (*link_failure)(struct sk_buff *);
  96         void                    (*update_pmtu)(struct dst_entry *dst, u32 mtu);
  97         int                     entry_size;
  98
  99         atomic_t                entries;
 100         kmem_cache_t            *kmem_cachep;
 101 };
 102
 103 #ifdef __KERNEL__
 104
 105 static inline u32
 106 dst_metric(const struct dst_entry *dst, int metric)
 107 {
 108         return dst->metrics[metric-1];
 109 }
 110
 111 static inline u32 dst_mtu(const struct dst_entry *dst)
 112 {
 113         u32 mtu = dst_metric(dst, RTAX_MTU);
 114         /*
 115          * Alexey put it here, so ask him about it :)
 116          */
 117         barrier();
 118         return mtu;
 119 }
 120
 121 static inline u32
 122 dst_allfrag(const struct dst_entry *dst)
 123 {
 124         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 125         /* Yes, _exactly_. This is paranoia. */
 126         barrier();
 127         return ret;
 128 }
 129
 130 static inline int
 131 dst_metric_locked(struct dst_entry *dst, int metric)
 132 {
 133         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 134 }
 135
 136 static inline void dst_hold(struct dst_entry * dst)
 137 {
 138         atomic_inc(&dst->__refcnt);
 139 }
 140
 141 static inline
 142 struct dst_entry * dst_clone(struct dst_entry * dst)
 143 {
 144         if (dst)
 145                 atomic_inc(&dst->__refcnt);
 146         return dst;
 147 }
 148
 149 static inline
 150 void dst_release(struct dst_entry * dst)
 151 {
 152         if (dst) {
 153                 WARN_ON(atomic_read(&dst->__refcnt) < 1);
 154                 smp_mb__before_atomic_dec();
 155                 atomic_dec(&dst->__refcnt);
 156         }
 157 }
 158
 159 /* Children define the path of the packet through the
 160  * Linux networking.  Thus, destinations are stackable.
 161  */
 162
 163 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 164 {
 165         struct dst_entry *child = dst_clone(dst->child);
 166
 167         dst_release(dst);
 168         return child;
 169 }
 170
 171 extern void * dst_alloc(struct dst_ops * ops);
 172 extern void __dst_free(struct dst_entry * dst);
 173 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 174
 175 static inline void dst_free(struct dst_entry * dst)
 176 {
 177         if (dst->obsolete > 1)
 178                 return;
 179         if (!atomic_read(&dst->__refcnt)) {
 180                 dst = dst_destroy(dst);
 181                 if (!dst)
 182                         return;
 183         }
 184         __dst_free(dst);
 185 }
 186
 187 static inline void dst_rcu_free(struct rcu_head *head)
 188 {
 189         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 190         dst_free(dst);
 191 }
 192
 193 static inline void dst_confirm(struct dst_entry *dst)
 194 {
 195         if (dst)
 196                 neigh_confirm(dst->neighbour);
 197 }
 198
 199 static inline void dst_negative_advice(struct dst_entry **dst_p)
 200 {
 201         struct dst_entry * dst = *dst_p;
 202         if (dst && dst->ops->negative_advice)
 203                 *dst_p = dst->ops->negative_advice(dst);
 204 }
 205
 206 static inline void dst_link_failure(struct sk_buff *skb)
 207 {
 208         struct dst_entry * dst = skb->dst;
 209         if (dst && dst->ops && dst->ops->link_failure)
 210                 dst->ops->link_failure(skb);
 211 }
 212
 213 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 214 {
 215         unsigned long expires = jiffies + timeout;
 216
 217         if (expires == 0)
 218                 expires = 1;
 219
 220         if (dst->expires == 0 || time_before(expires, dst->expires))
 221                 dst->expires = expires;
 222 }
 223
 224 /* Output packet to network from transport.  */
 225 static inline int dst_output(struct sk_buff *skb)
 226 {
 227         int err;
 228
 229         for (;;) {
 230                 err = skb->dst->output(skb);
 231
 232                 if (likely(err == 0))
 233                         return err;
 234                 if (unlikely(err != NET_XMIT_BYPASS))
 235                         return err;
 236         }
 237 }
 238
 239 /* Input packet from network to transport.  */
 240 static inline int dst_input(struct sk_buff *skb)
 241 {
 242         int err;
 243
 244         for (;;) {
 245                 err = skb->dst->input(skb);
 246
 247                 if (likely(err == 0))
 248                         return err;
 249                 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
 250                 if (unlikely(err != NET_XMIT_BYPASS))
 251                         return err;
 252         }
 253 }
 254
 255 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 256 {
 257         if (dst->obsolete)
 258                 dst = dst->ops->check(dst, cookie);
 259         return dst;
 260 }
 261
 262 extern void             dst_init(void);
 263
 264 struct flowi;
 265 #ifndef CONFIG_XFRM
 266 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 267                        struct sock *sk, int flags)
 268 {
 269         return 0;
 270 }
 271 #else
 272 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 273                        struct sock *sk, int flags);
 274 #endif
 275 #endif
 276
 277 #endif /* _NET_DST_H */