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 #define DST_BALANCED            0x10
  51         unsigned long           expires;
  52
  53         unsigned short          header_len;     /* more space at head required */
  54         unsigned short          nfheader_len;   /* more non-fragment 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         struct neighbour        *neighbour;
  64         struct hh_cache         *hh;
  65         struct xfrm_state       *xfrm;
  66
  67         int                     (*input)(struct sk_buff*);
  68         int                     (*output)(struct sk_buff*);
  69
  70 #ifdef CONFIG_NET_CLS_ROUTE
  71         __u32                   tclassid;
  72 #endif
  73
  74         struct  dst_ops         *ops;
  75
  76         unsigned long           lastuse;
  77         atomic_t                __refcnt;       /* client references    */
  78         int                     __use;
  79         union {
  80                 struct dst_entry *next;
  81                 struct rtable    *rt_next;
  82                 struct rt6_info   *rt6_next;
  83                 struct dn_route  *dn_next;
  84         };
  85         char                    info[0];
  86 };
  87
  88
  89 struct dst_ops
  90 {
  91         unsigned short          family;
  92         __be16                  protocol;
  93         unsigned                gc_thresh;
  94
  95         int                     (*gc)(void);
  96         struct dst_entry *      (*check)(struct dst_entry *, __u32 cookie);
  97         void                    (*destroy)(struct dst_entry *);
  98         void                    (*ifdown)(struct dst_entry *,
  99                                           struct net_device *dev, int how);
 100         struct dst_entry *      (*negative_advice)(struct dst_entry *);
 101         void                    (*link_failure)(struct sk_buff *);
 102         void                    (*update_pmtu)(struct dst_entry *dst, u32 mtu);
 103         int                     entry_size;
 104
 105         atomic_t                entries;
 106         struct kmem_cache               *kmem_cachep;
 107 };
 108
 109 #ifdef __KERNEL__
 110
 111 static inline u32
 112 dst_metric(const struct dst_entry *dst, int metric)
 113 {
 114         return dst->metrics[metric-1];
 115 }
 116
 117 static inline u32 dst_mtu(const struct dst_entry *dst)
 118 {
 119         u32 mtu = dst_metric(dst, RTAX_MTU);
 120         /*
 121          * Alexey put it here, so ask him about it :)
 122          */
 123         barrier();
 124         return mtu;
 125 }
 126
 127 static inline u32
 128 dst_allfrag(const struct dst_entry *dst)
 129 {
 130         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 131         /* Yes, _exactly_. This is paranoia. */
 132         barrier();
 133         return ret;
 134 }
 135
 136 static inline int
 137 dst_metric_locked(struct dst_entry *dst, int metric)
 138 {
 139         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 140 }
 141
 142 static inline void dst_hold(struct dst_entry * dst)
 143 {
 144         atomic_inc(&dst->__refcnt);
 145 }
 146
 147 static inline
 148 struct dst_entry * dst_clone(struct dst_entry * dst)
 149 {
 150         if (dst)
 151                 atomic_inc(&dst->__refcnt);
 152         return dst;
 153 }
 154
 155 static inline
 156 void dst_release(struct dst_entry * dst)
 157 {
 158         if (dst) {
 159                 WARN_ON(atomic_read(&dst->__refcnt) < 1);
 160                 smp_mb__before_atomic_dec();
 161                 atomic_dec(&dst->__refcnt);
 162         }
 163 }
 164
 165 /* Children define the path of the packet through the
 166  * Linux networking.  Thus, destinations are stackable.
 167  */
 168
 169 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 170 {
 171         struct dst_entry *child = dst_clone(dst->child);
 172
 173         dst_release(dst);
 174         return child;
 175 }
 176
 177 extern void * dst_alloc(struct dst_ops * ops);
 178 extern void __dst_free(struct dst_entry * dst);
 179 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 180
 181 static inline void dst_free(struct dst_entry * dst)
 182 {
 183         if (dst->obsolete > 1)
 184                 return;
 185         if (!atomic_read(&dst->__refcnt)) {
 186                 dst = dst_destroy(dst);
 187                 if (!dst)
 188                         return;
 189         }
 190         __dst_free(dst);
 191 }
 192
 193 static inline void dst_rcu_free(struct rcu_head *head)
 194 {
 195         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 196         dst_free(dst);
 197 }
 198
 199 static inline void dst_confirm(struct dst_entry *dst)
 200 {
 201         if (dst)
 202                 neigh_confirm(dst->neighbour);
 203 }
 204
 205 static inline void dst_negative_advice(struct dst_entry **dst_p)
 206 {
 207         struct dst_entry * dst = *dst_p;
 208         if (dst && dst->ops->negative_advice)
 209                 *dst_p = dst->ops->negative_advice(dst);
 210 }
 211
 212 static inline void dst_link_failure(struct sk_buff *skb)
 213 {
 214         struct dst_entry * dst = skb->dst;
 215         if (dst && dst->ops && dst->ops->link_failure)
 216                 dst->ops->link_failure(skb);
 217 }
 218
 219 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 220 {
 221         unsigned long expires = jiffies + timeout;
 222
 223         if (expires == 0)
 224                 expires = 1;
 225
 226         if (dst->expires == 0 || time_before(expires, dst->expires))
 227                 dst->expires = expires;
 228 }
 229
 230 /* Output packet to network from transport.  */
 231 static inline int dst_output(struct sk_buff *skb)
 232 {
 233         return skb->dst->output(skb);
 234 }
 235
 236 /* Input packet from network to transport.  */
 237 static inline int dst_input(struct sk_buff *skb)
 238 {
 239         int err;
 240
 241         for (;;) {
 242                 err = skb->dst->input(skb);
 243
 244                 if (likely(err == 0))
 245                         return err;
 246                 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
 247                 if (unlikely(err != NET_XMIT_BYPASS))
 248                         return err;
 249         }
 250 }
 251
 252 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 253 {
 254         if (dst->obsolete)
 255                 dst = dst->ops->check(dst, cookie);
 256         return dst;
 257 }
 258
 259 extern void             dst_init(void);
 260
 261 struct flowi;
 262 #ifndef CONFIG_XFRM
 263 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 264                        struct sock *sk, int flags)
 265 {
 266         return 0;
 267 }
 268 #else
 269 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 270                        struct sock *sk, int flags);
 271 #endif
 272 #endif
 273
 274 #endif /* _NET_DST_H */