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         int                     obsolete;
  46         int                     flags;
  47 #define DST_HOST                1
  48 #define DST_NOXFRM              2
  49 #define DST_NOPOLICY            4
  50 #define DST_NOHASH              8
  51 #define DST_BALANCED            0x10
  52         unsigned long           lastuse;
  53         unsigned long           expires;
  54
  55         unsigned short          header_len;     /* more space at head required */
  56         unsigned short          trailer_len;    /* space to reserve at tail */
  57
  58         u32                     metrics[RTAX_MAX];
  59         struct dst_entry        *path;
  60
  61         unsigned long           rate_last;      /* rate limiting for ICMP */
  62         unsigned long           rate_tokens;
  63
  64         int                     error;
  65
  66         struct neighbour        *neighbour;
  67         struct hh_cache         *hh;
  68         struct xfrm_state       *xfrm;
  69
  70         int                     (*input)(struct sk_buff*);
  71         int                     (*output)(struct sk_buff*);
  72
  73 #ifdef CONFIG_NET_CLS_ROUTE
  74         __u32                   tclassid;
  75 #endif
  76
  77         struct  dst_ops         *ops;
  78         struct rcu_head         rcu_head;
  79
  80         char                    info[0];
  81 };
  82
  83
  84 struct dst_ops
  85 {
  86         unsigned short          family;
  87         unsigned short          protocol;
  88         unsigned                gc_thresh;
  89
  90         int                     (*gc)(void);
  91         struct dst_entry *      (*check)(struct dst_entry *, __u32 cookie);
  92         void                    (*destroy)(struct dst_entry *);
  93         void                    (*ifdown)(struct dst_entry *,
  94                                           struct net_device *dev, int how);
  95         struct dst_entry *      (*negative_advice)(struct dst_entry *);
  96         void                    (*link_failure)(struct sk_buff *);
  97         void                    (*update_pmtu)(struct dst_entry *dst, u32 mtu);
  98         int                     (*get_mss)(struct dst_entry *dst, u32 mtu);
  99         int                     entry_size;
 100
 101         atomic_t                entries;
 102         kmem_cache_t            *kmem_cachep;
 103 };
 104
 105 #ifdef __KERNEL__
 106
 107 static inline u32
 108 dst_metric(const struct dst_entry *dst, int metric)
 109 {
 110         return dst->metrics[metric-1];
 111 }
 112
 113 static inline u32 dst_mtu(const struct dst_entry *dst)
 114 {
 115         u32 mtu = dst_metric(dst, RTAX_MTU);
 116         /*
 117          * Alexey put it here, so ask him about it :)
 118          */
 119         barrier();
 120         return mtu;
 121 }
 122
 123 static inline u32
 124 dst_allfrag(const struct dst_entry *dst)
 125 {
 126         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 127         /* Yes, _exactly_. This is paranoia. */
 128         barrier();
 129         return ret;
 130 }
 131
 132 static inline int
 133 dst_metric_locked(struct dst_entry *dst, int metric)
 134 {
 135         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 136 }
 137
 138 static inline void dst_hold(struct dst_entry * dst)
 139 {
 140         atomic_inc(&dst->__refcnt);
 141 }
 142
 143 static inline
 144 struct dst_entry * dst_clone(struct dst_entry * dst)
 145 {
 146         if (dst)
 147                 atomic_inc(&dst->__refcnt);
 148         return dst;
 149 }
 150
 151 static inline
 152 void dst_release(struct dst_entry * dst)
 153 {
 154         if (dst) {
 155                 WARN_ON(atomic_read(&dst->__refcnt) < 1);
 156                 smp_mb__before_atomic_dec();
 157                 atomic_dec(&dst->__refcnt);
 158         }
 159 }
 160
 161 /* Children define the path of the packet through the
 162  * Linux networking.  Thus, destinations are stackable.
 163  */
 164
 165 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 166 {
 167         struct dst_entry *child = dst_clone(dst->child);
 168
 169         dst_release(dst);
 170         return child;
 171 }
 172
 173 extern void * dst_alloc(struct dst_ops * ops);
 174 extern void __dst_free(struct dst_entry * dst);
 175 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 176
 177 static inline void dst_free(struct dst_entry * dst)
 178 {
 179         if (dst->obsolete > 1)
 180                 return;
 181         if (!atomic_read(&dst->__refcnt)) {
 182                 dst = dst_destroy(dst);
 183                 if (!dst)
 184                         return;
 185         }
 186         __dst_free(dst);
 187 }
 188
 189 static inline void dst_rcu_free(struct rcu_head *head)
 190 {
 191         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 192         dst_free(dst);
 193 }
 194
 195 static inline void dst_confirm(struct dst_entry *dst)
 196 {
 197         if (dst)
 198                 neigh_confirm(dst->neighbour);
 199 }
 200
 201 static inline void dst_negative_advice(struct dst_entry **dst_p)
 202 {
 203         struct dst_entry * dst = *dst_p;
 204         if (dst && dst->ops->negative_advice)
 205                 *dst_p = dst->ops->negative_advice(dst);
 206 }
 207
 208 static inline void dst_link_failure(struct sk_buff *skb)
 209 {
 210         struct dst_entry * dst = skb->dst;
 211         if (dst && dst->ops && dst->ops->link_failure)
 212                 dst->ops->link_failure(skb);
 213 }
 214
 215 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 216 {
 217         unsigned long expires = jiffies + timeout;
 218
 219         if (expires == 0)
 220                 expires = 1;
 221
 222         if (dst->expires == 0 || time_before(expires, dst->expires))
 223                 dst->expires = expires;
 224 }
 225
 226 /* Output packet to network from transport.  */
 227 static inline int dst_output(struct sk_buff *skb)
 228 {
 229         int err;
 230
 231         for (;;) {
 232                 err = skb->dst->output(skb);
 233
 234                 if (likely(err == 0))
 235                         return err;
 236                 if (unlikely(err != NET_XMIT_BYPASS))
 237                         return err;
 238         }
 239 }
 240
 241 /* Input packet from network to transport.  */
 242 static inline int dst_input(struct sk_buff *skb)
 243 {
 244         int err;
 245
 246         for (;;) {
 247                 err = skb->dst->input(skb);
 248
 249                 if (likely(err == 0))
 250                         return err;
 251                 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
 252                 if (unlikely(err != NET_XMIT_BYPASS))
 253                         return err;
 254         }
 255 }
 256
 257 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 258 {
 259         if (dst->obsolete)
 260                 dst = dst->ops->check(dst, cookie);
 261         return dst;
 262 }
 263
 264 extern void             dst_init(void);
 265
 266 struct flowi;
 267 #ifndef CONFIG_XFRM
 268 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 269                        struct sock *sk, int flags)
 270 {
 271         return 0;
 272 }
 273 #else
 274 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 275                        struct sock *sk, int flags);
 276 #endif
 277 #endif
 278
 279 #endif /* _NET_DST_H */