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         unsigned long           lastuse;
  52         unsigned long           expires;
  53
  54         unsigned short          header_len;     /* more space at head required */
  55         unsigned short          trailer_len;    /* space to reserve at tail */
  56
  57         u32                     metrics[RTAX_MAX];
  58         struct dst_entry        *path;
  59
  60         unsigned long           rate_last;      /* rate limiting for ICMP */
  61         unsigned long           rate_tokens;
  62
  63         int                     error;
  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         struct dst_entry *      (*negative_advice)(struct dst_entry *);
  93         void                    (*link_failure)(struct sk_buff *);
  94         void                    (*update_pmtu)(struct dst_entry *dst, u32 mtu);
  95         int                     (*get_mss)(struct dst_entry *dst, u32 mtu);
  96         int                     entry_size;
  97
  98         atomic_t                entries;
  99         kmem_cache_t            *kmem_cachep;
 100 };
 101
 102 #ifdef __KERNEL__
 103
 104 static inline u32
 105 dst_metric(struct dst_entry *dst, int metric)
 106 {
 107         return dst->metrics[metric-1];
 108 }
 109
 110 static inline u32
 111 dst_path_metric(struct dst_entry *dst, int metric)
 112 {
 113         return dst->path->metrics[metric-1];
 114 }
 115
 116 static inline u32
 117 dst_pmtu(struct dst_entry *dst)
 118 {
 119         u32 mtu = dst_path_metric(dst, RTAX_MTU);
 120         /* Yes, _exactly_. This is paranoia. */
 121         barrier();
 122         return mtu;
 123 }
 124
 125 static inline int
 126 dst_metric_locked(struct dst_entry *dst, int metric)
 127 {
 128         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 129 }
 130
 131 static inline void dst_hold(struct dst_entry * dst)
 132 {
 133         atomic_inc(&dst->__refcnt);
 134 }
 135
 136 static inline
 137 struct dst_entry * dst_clone(struct dst_entry * dst)
 138 {
 139         if (dst)
 140                 atomic_inc(&dst->__refcnt);
 141         return dst;
 142 }
 143
 144 static inline
 145 void dst_release(struct dst_entry * dst)
 146 {
 147         if (dst) {
 148                 if (atomic_read(&dst->__refcnt) < 1) {
 149                         printk("BUG: dst underflow %d: %p\n",
 150                                atomic_read(&dst->__refcnt),
 151                                current_text_addr());
 152                 }
 153                 atomic_dec(&dst->__refcnt);
 154         }
 155 }
 156
 157 /* Children define the path of the packet through the
 158  * Linux networking.  Thus, destinations are stackable.
 159  */
 160
 161 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 162 {
 163         struct dst_entry *child = dst_clone(dst->child);
 164
 165         dst_release(dst);
 166         return child;
 167 }
 168
 169 extern void * dst_alloc(struct dst_ops * ops);
 170 extern void __dst_free(struct dst_entry * dst);
 171 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 172
 173 static inline void dst_free(struct dst_entry * dst)
 174 {
 175         if (dst->obsolete > 1)
 176                 return;
 177         if (!atomic_read(&dst->__refcnt)) {
 178                 dst = dst_destroy(dst);
 179                 if (!dst)
 180                         return;
 181         }
 182         __dst_free(dst);
 183 }
 184
 185 static inline void dst_confirm(struct dst_entry *dst)
 186 {
 187         if (dst)
 188                 neigh_confirm(dst->neighbour);
 189 }
 190
 191 static inline void dst_negative_advice(struct dst_entry **dst_p)
 192 {
 193         struct dst_entry * dst = *dst_p;
 194         if (dst && dst->ops->negative_advice)
 195                 *dst_p = dst->ops->negative_advice(dst);
 196 }
 197
 198 static inline void dst_link_failure(struct sk_buff *skb)
 199 {
 200         struct dst_entry * dst = skb->dst;
 201         if (dst && dst->ops && dst->ops->link_failure)
 202                 dst->ops->link_failure(skb);
 203 }
 204
 205 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 206 {
 207         unsigned long expires = jiffies + timeout;
 208
 209         if (expires == 0)
 210                 expires = 1;
 211
 212         if (dst->expires == 0 || time_before(expires, dst->expires))
 213                 dst->expires = expires;
 214 }
 215
 216 /* Output packet to network from transport.  */
 217 static inline int dst_output(struct sk_buff *skb)
 218 {
 219         int err;
 220
 221         for (;;) {
 222                 err = skb->dst->output(skb);
 223
 224                 if (likely(err == 0))
 225                         return err;
 226                 if (unlikely(err != NET_XMIT_BYPASS))
 227                         return err;
 228         }
 229 }
 230
 231 /* Input packet from network to transport.  */
 232 static inline int dst_input(struct sk_buff *skb)
 233 {
 234         int err;
 235
 236         for (;;) {
 237                 err = skb->dst->input(skb);
 238
 239                 if (likely(err == 0))
 240                         return err;
 241                 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
 242                 if (unlikely(err != NET_XMIT_BYPASS))
 243                         return err;
 244         }
 245 }
 246
 247 extern void             dst_init(void);
 248
 249 struct flowi;
 250 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 251                        struct sock *sk, int flags);
 252 #endif
 253
 254 #endif /* _NET_DST_H */