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         unsigned long           expires;
  51
  52         unsigned short          header_len;     /* more space at head required */
  53         unsigned short          trailer_len;    /* space to reserve at tail */
  54
  55         unsigned int            rate_tokens;
  56         unsigned long           rate_last;      /* rate limiting for ICMP */
  57
  58         struct dst_entry        *path;
  59
  60         struct neighbour        *neighbour;
  61         struct hh_cache         *hh;
  62         struct xfrm_state       *xfrm;
  63
  64         int                     (*input)(struct sk_buff*);
  65         int                     (*output)(struct sk_buff*);
  66
  67         struct  dst_ops         *ops;
  68
  69         u32                     metrics[RTAX_MAX];
  70
  71 #ifdef CONFIG_NET_CLS_ROUTE
  72         __u32                   tclassid;
  73 #endif
  74
  75         /*
  76          * __refcnt wants to be on a different cache line from
  77          * input/output/ops or performance tanks badly
  78          */
  79         atomic_t                __refcnt;       /* client references    */
  80         int                     __use;
  81         unsigned long           lastuse;
  82         union {
  83                 struct dst_entry *next;
  84                 struct rtable    *rt_next;
  85                 struct rt6_info   *rt6_next;
  86                 struct dn_route  *dn_next;
  87         };
  88 };
  89
  90
  91 struct dst_ops
  92 {
  93         unsigned short          family;
  94         __be16                  protocol;
  95         unsigned                gc_thresh;
  96
  97         int                     (*gc)(struct dst_ops *ops);
  98         struct dst_entry *      (*check)(struct dst_entry *, __u32 cookie);
  99         void                    (*destroy)(struct dst_entry *);
 100         void                    (*ifdown)(struct dst_entry *,
 101                                           struct net_device *dev, int how);
 102         struct dst_entry *      (*negative_advice)(struct dst_entry *);
 103         void                    (*link_failure)(struct sk_buff *);
 104         void                    (*update_pmtu)(struct dst_entry *dst, u32 mtu);
 105         int                     (*local_out)(struct sk_buff *skb);
 106         int                     entry_size;
 107
 108         atomic_t                entries;
 109         struct kmem_cache               *kmem_cachep;
 110         struct net              *dst_net;
 111 };
 112
 113 #ifdef __KERNEL__
 114
 115 static inline u32
 116 dst_metric(const struct dst_entry *dst, int metric)
 117 {
 118         return dst->metrics[metric-1];
 119 }
 120
 121 static inline u32 dst_mtu(const struct dst_entry *dst)
 122 {
 123         u32 mtu = dst_metric(dst, RTAX_MTU);
 124         /*
 125          * Alexey put it here, so ask him about it :)
 126          */
 127         barrier();
 128         return mtu;
 129 }
 130
 131 static inline u32
 132 dst_allfrag(const struct dst_entry *dst)
 133 {
 134         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 135         /* Yes, _exactly_. This is paranoia. */
 136         barrier();
 137         return ret;
 138 }
 139
 140 static inline int
 141 dst_metric_locked(struct dst_entry *dst, int metric)
 142 {
 143         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 144 }
 145
 146 static inline void dst_hold(struct dst_entry * dst)
 147 {
 148         atomic_inc(&dst->__refcnt);
 149 }
 150
 151 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 152 {
 153         dst_hold(dst);
 154         dst->__use++;
 155         dst->lastuse = time;
 156 }
 157
 158 static inline
 159 struct dst_entry * dst_clone(struct dst_entry * dst)
 160 {
 161         if (dst)
 162                 atomic_inc(&dst->__refcnt);
 163         return dst;
 164 }
 165
 166 extern void dst_release(struct dst_entry *dst);
 167
 168 /* Children define the path of the packet through the
 169  * Linux networking.  Thus, destinations are stackable.
 170  */
 171
 172 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 173 {
 174         struct dst_entry *child = dst_clone(dst->child);
 175
 176         dst_release(dst);
 177         return child;
 178 }
 179
 180 extern int dst_discard(struct sk_buff *skb);
 181 extern void * dst_alloc(struct dst_ops * ops);
 182 extern void __dst_free(struct dst_entry * dst);
 183 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 184
 185 static inline void dst_free(struct dst_entry * dst)
 186 {
 187         if (dst->obsolete > 1)
 188                 return;
 189         if (!atomic_read(&dst->__refcnt)) {
 190                 dst = dst_destroy(dst);
 191                 if (!dst)
 192                         return;
 193         }
 194         __dst_free(dst);
 195 }
 196
 197 static inline void dst_rcu_free(struct rcu_head *head)
 198 {
 199         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 200         dst_free(dst);
 201 }
 202
 203 static inline void dst_confirm(struct dst_entry *dst)
 204 {
 205         if (dst)
 206                 neigh_confirm(dst->neighbour);
 207 }
 208
 209 static inline void dst_negative_advice(struct dst_entry **dst_p)
 210 {
 211         struct dst_entry * dst = *dst_p;
 212         if (dst && dst->ops->negative_advice)
 213                 *dst_p = dst->ops->negative_advice(dst);
 214 }
 215
 216 static inline void dst_link_failure(struct sk_buff *skb)
 217 {
 218         struct dst_entry * dst = skb->dst;
 219         if (dst && dst->ops && dst->ops->link_failure)
 220                 dst->ops->link_failure(skb);
 221 }
 222
 223 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 224 {
 225         unsigned long expires = jiffies + timeout;
 226
 227         if (expires == 0)
 228                 expires = 1;
 229
 230         if (dst->expires == 0 || time_before(expires, dst->expires))
 231                 dst->expires = expires;
 232 }
 233
 234 /* Output packet to network from transport.  */
 235 static inline int dst_output(struct sk_buff *skb)
 236 {
 237         return skb->dst->output(skb);
 238 }
 239
 240 /* Input packet from network to transport.  */
 241 static inline int dst_input(struct sk_buff *skb)
 242 {
 243         int err;
 244
 245         for (;;) {
 246                 err = skb->dst->input(skb);
 247
 248                 if (likely(err == 0))
 249                         return err;
 250                 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */
 251                 if (unlikely(err != NET_XMIT_BYPASS))
 252                         return err;
 253         }
 254 }
 255
 256 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 257 {
 258         if (dst->obsolete)
 259                 dst = dst->ops->check(dst, cookie);
 260         return dst;
 261 }
 262
 263 extern void             dst_init(void);
 264
 265 /* Flags for xfrm_lookup flags argument. */
 266 enum {
 267         XFRM_LOOKUP_WAIT = 1 << 0,
 268         XFRM_LOOKUP_ICMP = 1 << 1,
 269 };
 270
 271 struct flowi;
 272 #ifndef CONFIG_XFRM
 273 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 274                        struct sock *sk, int flags)
 275 {
 276         return 0;
 277 }
 278 static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 279                                 struct sock *sk, int flags)
 280 {
 281         return 0;
 282 }
 283 #else
 284 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 285                        struct sock *sk, int flags);
 286 extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl,
 287                          struct sock *sk, int flags);
 288 #endif
 289 #endif
 290
 291 #endif /* _NET_DST_H */