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 <net/dst_ops.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/rtnetlink.h>
  14 #include <linux/rcupdate.h>
  15 #include <linux/jiffies.h>
  16 #include <net/neighbour.h>
  17 #include <asm/processor.h>
  18
  19 /*
  20  * 0 - no debugging messages
  21  * 1 - rare events and bugs (default)
  22  * 2 - trace mode.
  23  */
  24 #define RT_CACHE_DEBUG          0
  25
  26 #define DST_GC_MIN      (HZ/10)
  27 #define DST_GC_INC      (HZ/2)
  28 #define DST_GC_MAX      (120*HZ)
  29
  30 /* Each dst_entry has reference count and sits in some parent list(s).
  31  * When it is removed from parent list, it is "freed" (dst_free).
  32  * After this it enters dead state (dst->obsolete > 0) and if its refcnt
  33  * is zero, it can be destroyed immediately, otherwise it is added
  34  * to gc list and garbage collector periodically checks the refcnt.
  35  */
  36
  37 struct sk_buff;
  38
  39 struct dst_entry {
  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 #ifdef __KERNEL__
 106
 107 static inline u32
 108 dst_metric(const struct dst_entry *dst, int metric)
 109 {
 110         return dst->metrics[metric-1];
 111 }
 112
 113 static inline u32
 114 dst_feature(const struct dst_entry *dst, u32 feature)
 115 {
 116         return (dst ? dst_metric(dst, RTAX_FEATURES) & feature : 0);
 117 }
 118
 119 static inline u32 dst_mtu(const struct dst_entry *dst)
 120 {
 121         u32 mtu = dst_metric(dst, RTAX_MTU);
 122         /*
 123          * Alexey put it here, so ask him about it :)
 124          */
 125         barrier();
 126         return mtu;
 127 }
 128
 129 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 130 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 131 {
 132         return msecs_to_jiffies(dst_metric(dst, metric));
 133 }
 134
 135 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 136                                       unsigned long rtt)
 137 {
 138         dst->metrics[metric-1] = jiffies_to_msecs(rtt);
 139 }
 140
 141 static inline u32
 142 dst_allfrag(const struct dst_entry *dst)
 143 {
 144         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 145         /* Yes, _exactly_. This is paranoia. */
 146         barrier();
 147         return ret;
 148 }
 149
 150 static inline int
 151 dst_metric_locked(struct dst_entry *dst, int metric)
 152 {
 153         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 154 }
 155
 156 static inline void dst_hold(struct dst_entry * dst)
 157 {
 158         /*
 159          * If your kernel compilation stops here, please check
 160          * __pad_to_align_refcnt declaration in struct dst_entry
 161          */
 162         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 163         atomic_inc(&dst->__refcnt);
 164 }
 165
 166 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 167 {
 168         dst_hold(dst);
 169         dst->__use++;
 170         dst->lastuse = time;
 171 }
 172
 173 static inline
 174 struct dst_entry * dst_clone(struct dst_entry * dst)
 175 {
 176         if (dst)
 177                 atomic_inc(&dst->__refcnt);
 178         return dst;
 179 }
 180
 181 extern void dst_release(struct dst_entry *dst);
 182 static inline void skb_dst_drop(struct sk_buff *skb)
 183 {
 184         if (skb->_skb_dst)
 185                 dst_release(skb_dst(skb));
 186         skb->_skb_dst = 0UL;
 187 }
 188
 189 /* Children define the path of the packet through the
 190  * Linux networking.  Thus, destinations are stackable.
 191  */
 192
 193 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 194 {
 195         struct dst_entry *child = dst_clone(dst->child);
 196
 197         dst_release(dst);
 198         return child;
 199 }
 200
 201 extern int dst_discard(struct sk_buff *skb);
 202 extern void * dst_alloc(struct dst_ops * ops);
 203 extern void __dst_free(struct dst_entry * dst);
 204 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 205
 206 static inline void dst_free(struct dst_entry * dst)
 207 {
 208         if (dst->obsolete > 1)
 209                 return;
 210         if (!atomic_read(&dst->__refcnt)) {
 211                 dst = dst_destroy(dst);
 212                 if (!dst)
 213                         return;
 214         }
 215         __dst_free(dst);
 216 }
 217
 218 static inline void dst_rcu_free(struct rcu_head *head)
 219 {
 220         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 221         dst_free(dst);
 222 }
 223
 224 static inline void dst_confirm(struct dst_entry *dst)
 225 {
 226         if (dst)
 227                 neigh_confirm(dst->neighbour);
 228 }
 229
 230 static inline void dst_negative_advice(struct dst_entry **dst_p,
 231                                        struct sock *sk)
 232 {
 233         struct dst_entry * dst = *dst_p;
 234         if (dst && dst->ops->negative_advice) {
 235                 *dst_p = dst->ops->negative_advice(dst);
 236
 237                 if (dst != *dst_p) {
 238                         extern void sk_reset_txq(struct sock *sk);
 239
 240                         sk_reset_txq(sk);
 241                 }
 242         }
 243 }
 244
 245 static inline void dst_link_failure(struct sk_buff *skb)
 246 {
 247         struct dst_entry *dst = skb_dst(skb);
 248         if (dst && dst->ops && dst->ops->link_failure)
 249                 dst->ops->link_failure(skb);
 250 }
 251
 252 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 253 {
 254         unsigned long expires = jiffies + timeout;
 255
 256         if (expires == 0)
 257                 expires = 1;
 258
 259         if (dst->expires == 0 || time_before(expires, dst->expires))
 260                 dst->expires = expires;
 261 }
 262
 263 /* Output packet to network from transport.  */
 264 static inline int dst_output(struct sk_buff *skb)
 265 {
 266         return skb_dst(skb)->output(skb);
 267 }
 268
 269 /* Input packet from network to transport.  */
 270 static inline int dst_input(struct sk_buff *skb)
 271 {
 272         return skb_dst(skb)->input(skb);
 273 }
 274
 275 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 276 {
 277         if (dst->obsolete)
 278                 dst = dst->ops->check(dst, cookie);
 279         return dst;
 280 }
 281
 282 extern void             dst_init(void);
 283
 284 /* Flags for xfrm_lookup flags argument. */
 285 enum {
 286         XFRM_LOOKUP_WAIT = 1 << 0,
 287         XFRM_LOOKUP_ICMP = 1 << 1,
 288 };
 289
 290 struct flowi;
 291 #ifndef CONFIG_XFRM
 292 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 293                               struct flowi *fl, struct sock *sk, int flags)
 294 {
 295         return 0;
 296 }
 297 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 298                                 struct flowi *fl, struct sock *sk, int flags)
 299 {
 300         return 0;
 301 }
 302 #else
 303 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 304                        struct flowi *fl, struct sock *sk, int flags);
 305 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 306                          struct flowi *fl, struct sock *sk, int flags);
 307 #endif
 308 #endif
 309
 310 #endif /* _NET_DST_H */