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 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          nfheader_len;   /* more non-fragment space at head required */
  58         unsigned short          trailer_len;    /* space to reserve at tail */
  59
  60         u32                     metrics[RTAX_MAX];
  61         struct dst_entry        *path;
  62
  63         unsigned long           rate_last;      /* rate limiting for ICMP */
  64         unsigned long           rate_tokens;
  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                     entry_size;
  99
 100         atomic_t                entries;
 101         kmem_cache_t            *kmem_cachep;
 102 };
 103
 104 #ifdef __KERNEL__
 105
 106 static inline u32
 107 dst_metric(const struct dst_entry *dst, int metric)
 108 {
 109         return dst->metrics[metric-1];
 110 }
 111
 112 static inline u32 dst_mtu(const struct dst_entry *dst)
 113 {
 114         u32 mtu = dst_metric(dst, RTAX_MTU);
 115         /*
 116          * Alexey put it here, so ask him about it :)
 117          */
 118         barrier();
 119         return mtu;
 120 }
 121
 122 static inline u32
 123 dst_allfrag(const struct dst_entry *dst)
 124 {
 125         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 126         /* Yes, _exactly_. This is paranoia. */
 127         barrier();
 128         return ret;
 129 }
 130
 131 static inline int
 132 dst_metric_locked(struct dst_entry *dst, int metric)
 133 {
 134         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 135 }
 136
 137 static inline void dst_hold(struct dst_entry * dst)
 138 {
 139         atomic_inc(&dst->__refcnt);
 140 }
 141
 142 static inline
 143 struct dst_entry * dst_clone(struct dst_entry * dst)
 144 {
 145         if (dst)
 146                 atomic_inc(&dst->__refcnt);
 147         return dst;
 148 }
 149
 150 static inline
 151 void dst_release(struct dst_entry * dst)
 152 {
 153         if (dst) {
 154                 WARN_ON(atomic_read(&dst->__refcnt) < 1);
 155                 smp_mb__before_atomic_dec();
 156                 atomic_dec(&dst->__refcnt);
 157         }
 158 }
 159
 160 /* Children define the path of the packet through the
 161  * Linux networking.  Thus, destinations are stackable.
 162  */
 163
 164 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 165 {
 166         struct dst_entry *child = dst_clone(dst->child);
 167
 168         dst_release(dst);
 169         return child;
 170 }
 171
 172 extern void * dst_alloc(struct dst_ops * ops);
 173 extern void __dst_free(struct dst_entry * dst);
 174 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 175
 176 static inline void dst_free(struct dst_entry * dst)
 177 {
 178         if (dst->obsolete > 1)
 179                 return;
 180         if (!atomic_read(&dst->__refcnt)) {
 181                 dst = dst_destroy(dst);
 182                 if (!dst)
 183                         return;
 184         }
 185         __dst_free(dst);
 186 }
 187
 188 static inline void dst_rcu_free(struct rcu_head *head)
 189 {
 190         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 191         dst_free(dst);
 192 }
 193
 194 static inline void dst_confirm(struct dst_entry *dst)
 195 {
 196         if (dst)
 197                 neigh_confirm(dst->neighbour);
 198 }
 199
 200 static inline void dst_negative_advice(struct dst_entry **dst_p)
 201 {
 202         struct dst_entry * dst = *dst_p;
 203         if (dst && dst->ops->negative_advice)
 204                 *dst_p = dst->ops->negative_advice(dst);
 205 }
 206
 207 static inline void dst_link_failure(struct sk_buff *skb)
 208 {
 209         struct dst_entry * dst = skb->dst;
 210         if (dst && dst->ops && dst->ops->link_failure)
 211                 dst->ops->link_failure(skb);
 212 }
 213
 214 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 215 {
 216         unsigned long expires = jiffies + timeout;
 217
 218         if (expires == 0)
 219                 expires = 1;
 220
 221         if (dst->expires == 0 || time_before(expires, dst->expires))
 222                 dst->expires = expires;
 223 }
 224
 225 /* Output packet to network from transport.  */
 226 static inline int dst_output(struct sk_buff *skb)
 227 {
 228         return skb->dst->output(skb);
 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 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 248 {
 249         if (dst->obsolete)
 250                 dst = dst->ops->check(dst, cookie);
 251         return dst;
 252 }
 253
 254 extern void             dst_init(void);
 255
 256 struct flowi;
 257 #ifndef CONFIG_XFRM
 258 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 259                        struct sock *sk, int flags)
 260 {
 261         return 0;
 262 }
 263 #else
 264 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 265                        struct sock *sk, int flags);
 266 #endif
 267 #endif
 268
 269 #endif /* _NET_DST_H */