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 #ifdef CONFIG_XFRM
  63         struct xfrm_state       *xfrm;
  64 #else
  65         void                    *__pad1;
  66 #endif
  67         int                     (*input)(struct sk_buff*);
  68         int                     (*output)(struct sk_buff*);
  69
  70         struct  dst_ops         *ops;
  71
  72         u32                     metrics[RTAX_MAX];
  73
  74 #ifdef CONFIG_NET_CLS_ROUTE
  75         __u32                   tclassid;
  76 #else
  77         __u32                   __pad2;
  78 #endif
  79
  80
  81         /*
  82          * Align __refcnt to a 64 bytes alignment
  83          * (L1_CACHE_SIZE would be too much)
  84          */
  85 #ifdef CONFIG_64BIT
  86         long                    __pad_to_align_refcnt[2];
  87 #else
  88         long                    __pad_to_align_refcnt[1];
  89 #endif
  90         /*
  91          * __refcnt wants to be on a different cache line from
  92          * input/output/ops or performance tanks badly
  93          */
  94         atomic_t                __refcnt;       /* client references    */
  95         int                     __use;
  96         unsigned long           lastuse;
  97         union {
  98                 struct dst_entry *next;
  99                 struct rtable    *rt_next;
 100                 struct rt6_info   *rt6_next;
 101                 struct dn_route  *dn_next;
 102         };
 103 };
 104
 105
 106 struct dst_ops
 107 {
 108         unsigned short          family;
 109         __be16                  protocol;
 110         unsigned                gc_thresh;
 111
 112         int                     (*gc)(struct dst_ops *ops);
 113         struct dst_entry *      (*check)(struct dst_entry *, __u32 cookie);
 114         void                    (*destroy)(struct dst_entry *);
 115         void                    (*ifdown)(struct dst_entry *,
 116                                           struct net_device *dev, int how);
 117         struct dst_entry *      (*negative_advice)(struct dst_entry *);
 118         void                    (*link_failure)(struct sk_buff *);
 119         void                    (*update_pmtu)(struct dst_entry *dst, u32 mtu);
 120         int                     (*local_out)(struct sk_buff *skb);
 121
 122         atomic_t                entries;
 123         struct kmem_cache               *kmem_cachep;
 124         struct net              *dst_net;
 125 };
 126
 127 #ifdef __KERNEL__
 128
 129 static inline u32
 130 dst_metric(const struct dst_entry *dst, int metric)
 131 {
 132         return dst->metrics[metric-1];
 133 }
 134
 135 static inline u32 dst_mtu(const struct dst_entry *dst)
 136 {
 137         u32 mtu = dst_metric(dst, RTAX_MTU);
 138         /*
 139          * Alexey put it here, so ask him about it :)
 140          */
 141         barrier();
 142         return mtu;
 143 }
 144
 145 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 146 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 147 {
 148         return msecs_to_jiffies(dst_metric(dst, metric));
 149 }
 150
 151 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 152                                       unsigned long rtt)
 153 {
 154         dst->metrics[metric-1] = jiffies_to_msecs(rtt);
 155 }
 156
 157 static inline u32
 158 dst_allfrag(const struct dst_entry *dst)
 159 {
 160         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 161         /* Yes, _exactly_. This is paranoia. */
 162         barrier();
 163         return ret;
 164 }
 165
 166 static inline int
 167 dst_metric_locked(struct dst_entry *dst, int metric)
 168 {
 169         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 170 }
 171
 172 static inline void dst_hold(struct dst_entry * dst)
 173 {
 174         /*
 175          * If your kernel compilation stops here, please check
 176          * __pad_to_align_refcnt declaration in struct dst_entry
 177          */
 178         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 179         atomic_inc(&dst->__refcnt);
 180 }
 181
 182 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 183 {
 184         dst_hold(dst);
 185         dst->__use++;
 186         dst->lastuse = time;
 187 }
 188
 189 static inline
 190 struct dst_entry * dst_clone(struct dst_entry * dst)
 191 {
 192         if (dst)
 193                 atomic_inc(&dst->__refcnt);
 194         return dst;
 195 }
 196
 197 extern void dst_release(struct dst_entry *dst);
 198
 199 /* Children define the path of the packet through the
 200  * Linux networking.  Thus, destinations are stackable.
 201  */
 202
 203 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 204 {
 205         struct dst_entry *child = dst_clone(dst->child);
 206
 207         dst_release(dst);
 208         return child;
 209 }
 210
 211 extern int dst_discard(struct sk_buff *skb);
 212 extern void * dst_alloc(struct dst_ops * ops);
 213 extern void __dst_free(struct dst_entry * dst);
 214 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 215
 216 static inline void dst_free(struct dst_entry * dst)
 217 {
 218         if (dst->obsolete > 1)
 219                 return;
 220         if (!atomic_read(&dst->__refcnt)) {
 221                 dst = dst_destroy(dst);
 222                 if (!dst)
 223                         return;
 224         }
 225         __dst_free(dst);
 226 }
 227
 228 static inline void dst_rcu_free(struct rcu_head *head)
 229 {
 230         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 231         dst_free(dst);
 232 }
 233
 234 static inline void dst_confirm(struct dst_entry *dst)
 235 {
 236         if (dst)
 237                 neigh_confirm(dst->neighbour);
 238 }
 239
 240 static inline void dst_negative_advice(struct dst_entry **dst_p)
 241 {
 242         struct dst_entry * dst = *dst_p;
 243         if (dst && dst->ops->negative_advice)
 244                 *dst_p = dst->ops->negative_advice(dst);
 245 }
 246
 247 static inline void dst_link_failure(struct sk_buff *skb)
 248 {
 249         struct dst_entry * dst = skb->dst;
 250         if (dst && dst->ops && dst->ops->link_failure)
 251                 dst->ops->link_failure(skb);
 252 }
 253
 254 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 255 {
 256         unsigned long expires = jiffies + timeout;
 257
 258         if (expires == 0)
 259                 expires = 1;
 260
 261         if (dst->expires == 0 || time_before(expires, dst->expires))
 262                 dst->expires = expires;
 263 }
 264
 265 /* Output packet to network from transport.  */
 266 static inline int dst_output(struct sk_buff *skb)
 267 {
 268         return skb->dst->output(skb);
 269 }
 270
 271 /* Input packet from network to transport.  */
 272 static inline int dst_input(struct sk_buff *skb)
 273 {
 274         return skb->dst->input(skb);
 275 }
 276
 277 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 278 {
 279         if (dst->obsolete)
 280                 dst = dst->ops->check(dst, cookie);
 281         return dst;
 282 }
 283
 284 extern void             dst_init(void);
 285
 286 /* Flags for xfrm_lookup flags argument. */
 287 enum {
 288         XFRM_LOOKUP_WAIT = 1 << 0,
 289         XFRM_LOOKUP_ICMP = 1 << 1,
 290 };
 291
 292 struct flowi;
 293 #ifndef CONFIG_XFRM
 294 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 295                               struct flowi *fl, struct sock *sk, int flags)
 296 {
 297         return 0;
 298 }
 299 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 300                                 struct flowi *fl, struct sock *sk, int flags)
 301 {
 302         return 0;
 303 }
 304 #else
 305 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 306                        struct flowi *fl, struct sock *sk, int flags);
 307 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 308                          struct flowi *fl, struct sock *sk, int flags);
 309 #endif
 310 #endif
 311
 312 #endif /* _NET_DST_H */