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 {
  41         struct rcu_head         rcu_head;
  42         struct dst_entry        *child;
  43         struct net_device       *dev;
  44         short                   error;
  45         short                   obsolete;
  46         int                     flags;
  47 #define DST_HOST                1
  48 #define DST_NOXFRM              2
  49 #define DST_NOPOLICY            4
  50 #define DST_NOHASH              8
  51         unsigned long           expires;
  52
  53         unsigned short          header_len;     /* more space at head required */
  54         unsigned short          trailer_len;    /* space to reserve at tail */
  55
  56         unsigned int            rate_tokens;
  57         unsigned long           rate_last;      /* rate limiting for ICMP */
  58
  59         struct dst_entry        *path;
  60
  61         struct neighbour        *neighbour;
  62         struct hh_cache         *hh;
  63 #ifdef CONFIG_XFRM
  64         struct xfrm_state       *xfrm;
  65 #else
  66         void                    *__pad1;
  67 #endif
  68         int                     (*input)(struct sk_buff*);
  69         int                     (*output)(struct sk_buff*);
  70
  71         struct  dst_ops         *ops;
  72
  73         u32                     metrics[RTAX_MAX];
  74
  75 #ifdef CONFIG_NET_CLS_ROUTE
  76         __u32                   tclassid;
  77 #else
  78         __u32                   __pad2;
  79 #endif
  80
  81
  82         /*
  83          * Align __refcnt to a 64 bytes alignment
  84          * (L1_CACHE_SIZE would be too much)
  85          */
  86 #ifdef CONFIG_64BIT
  87         long                    __pad_to_align_refcnt[2];
  88 #else
  89         long                    __pad_to_align_refcnt[1];
  90 #endif
  91         /*
  92          * __refcnt wants to be on a different cache line from
  93          * input/output/ops or performance tanks badly
  94          */
  95         atomic_t                __refcnt;       /* client references    */
  96         int                     __use;
  97         unsigned long           lastuse;
  98         union {
  99                 struct dst_entry *next;
 100                 struct rtable    *rt_next;
 101                 struct rt6_info   *rt6_next;
 102                 struct dn_route  *dn_next;
 103         };
 104 };
 105
 106 #ifdef __KERNEL__
 107
 108 static inline u32
 109 dst_metric(const struct dst_entry *dst, int metric)
 110 {
 111         return dst->metrics[metric-1];
 112 }
 113
 114 static inline u32 dst_mtu(const struct dst_entry *dst)
 115 {
 116         u32 mtu = dst_metric(dst, RTAX_MTU);
 117         /*
 118          * Alexey put it here, so ask him about it :)
 119          */
 120         barrier();
 121         return mtu;
 122 }
 123
 124 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 125 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 126 {
 127         return msecs_to_jiffies(dst_metric(dst, metric));
 128 }
 129
 130 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 131                                       unsigned long rtt)
 132 {
 133         dst->metrics[metric-1] = jiffies_to_msecs(rtt);
 134 }
 135
 136 static inline u32
 137 dst_allfrag(const struct dst_entry *dst)
 138 {
 139         int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG;
 140         /* Yes, _exactly_. This is paranoia. */
 141         barrier();
 142         return ret;
 143 }
 144
 145 static inline int
 146 dst_metric_locked(struct dst_entry *dst, int metric)
 147 {
 148         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 149 }
 150
 151 static inline void dst_hold(struct dst_entry * dst)
 152 {
 153         /*
 154          * If your kernel compilation stops here, please check
 155          * __pad_to_align_refcnt declaration in struct dst_entry
 156          */
 157         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 158         atomic_inc(&dst->__refcnt);
 159 }
 160
 161 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 162 {
 163         dst_hold(dst);
 164         dst->__use++;
 165         dst->lastuse = time;
 166 }
 167
 168 static inline
 169 struct dst_entry * dst_clone(struct dst_entry * dst)
 170 {
 171         if (dst)
 172                 atomic_inc(&dst->__refcnt);
 173         return dst;
 174 }
 175
 176 extern void dst_release(struct dst_entry *dst);
 177 static inline void skb_dst_drop(struct sk_buff *skb)
 178 {
 179         if (skb->_skb_dst)
 180                 dst_release(skb_dst(skb));
 181         skb->_skb_dst = 0UL;
 182 }
 183
 184 /* Children define the path of the packet through the
 185  * Linux networking.  Thus, destinations are stackable.
 186  */
 187
 188 static inline struct dst_entry *dst_pop(struct dst_entry *dst)
 189 {
 190         struct dst_entry *child = dst_clone(dst->child);
 191
 192         dst_release(dst);
 193         return child;
 194 }
 195
 196 extern int dst_discard(struct sk_buff *skb);
 197 extern void * dst_alloc(struct dst_ops * ops);
 198 extern void __dst_free(struct dst_entry * dst);
 199 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 200
 201 static inline void dst_free(struct dst_entry * dst)
 202 {
 203         if (dst->obsolete > 1)
 204                 return;
 205         if (!atomic_read(&dst->__refcnt)) {
 206                 dst = dst_destroy(dst);
 207                 if (!dst)
 208                         return;
 209         }
 210         __dst_free(dst);
 211 }
 212
 213 static inline void dst_rcu_free(struct rcu_head *head)
 214 {
 215         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 216         dst_free(dst);
 217 }
 218
 219 static inline void dst_confirm(struct dst_entry *dst)
 220 {
 221         if (dst)
 222                 neigh_confirm(dst->neighbour);
 223 }
 224
 225 static inline void dst_negative_advice(struct dst_entry **dst_p,
 226                                        struct sock *sk)
 227 {
 228         struct dst_entry * dst = *dst_p;
 229         if (dst && dst->ops->negative_advice) {
 230                 *dst_p = dst->ops->negative_advice(dst);
 231
 232                 if (dst != *dst_p) {
 233                         extern void sk_reset_txq(struct sock *sk);
 234
 235                         sk_reset_txq(sk);
 236                 }
 237         }
 238 }
 239
 240 static inline void dst_link_failure(struct sk_buff *skb)
 241 {
 242         struct dst_entry *dst = skb_dst(skb);
 243         if (dst && dst->ops && dst->ops->link_failure)
 244                 dst->ops->link_failure(skb);
 245 }
 246
 247 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 248 {
 249         unsigned long expires = jiffies + timeout;
 250
 251         if (expires == 0)
 252                 expires = 1;
 253
 254         if (dst->expires == 0 || time_before(expires, dst->expires))
 255                 dst->expires = expires;
 256 }
 257
 258 /* Output packet to network from transport.  */
 259 static inline int dst_output(struct sk_buff *skb)
 260 {
 261         return skb_dst(skb)->output(skb);
 262 }
 263
 264 /* Input packet from network to transport.  */
 265 static inline int dst_input(struct sk_buff *skb)
 266 {
 267         return skb_dst(skb)->input(skb);
 268 }
 269
 270 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 271 {
 272         if (dst->obsolete)
 273                 dst = dst->ops->check(dst, cookie);
 274         return dst;
 275 }
 276
 277 extern void             dst_init(void);
 278
 279 /* Flags for xfrm_lookup flags argument. */
 280 enum {
 281         XFRM_LOOKUP_WAIT = 1 << 0,
 282         XFRM_LOOKUP_ICMP = 1 << 1,
 283 };
 284
 285 struct flowi;
 286 #ifndef CONFIG_XFRM
 287 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 288                               struct flowi *fl, struct sock *sk, int flags)
 289 {
 290         return 0;
 291 }
 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 #else
 298 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 299                        struct flowi *fl, struct sock *sk, int flags);
 300 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 301                          struct flowi *fl, struct sock *sk, int flags);
 302 #endif
 303 #endif
 304
 305 #endif /* _NET_DST_H */