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[1];
  87 #endif
  88         /*
  89          * __refcnt wants to be on a different cache line from
  90          * input/output/ops or performance tanks badly
  91          */
  92         atomic_t                __refcnt;       /* client references    */
  93         int                     __use;
  94         unsigned long           lastuse;
  95         union {
  96                 struct dst_entry *next;
  97                 struct rtable    *rt_next;
  98                 struct rt6_info   *rt6_next;
  99                 struct dn_route  *dn_next;
 100         };
 101 };
 102
 103 #ifdef __KERNEL__
 104
 105 static inline u32
 106 dst_metric(const struct dst_entry *dst, int metric)
 107 {
 108         return dst->metrics[metric-1];
 109 }
 110
 111 static inline u32
 112 dst_feature(const struct dst_entry *dst, u32 feature)
 113 {
 114         return dst_metric(dst, RTAX_FEATURES) & feature;
 115 }
 116
 117 static inline u32 dst_mtu(const struct dst_entry *dst)
 118 {
 119         u32 mtu = dst_metric(dst, RTAX_MTU);
 120         /*
 121          * Alexey put it here, so ask him about it :)
 122          */
 123         barrier();
 124         return mtu;
 125 }
 126
 127 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
 128 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
 129 {
 130         return msecs_to_jiffies(dst_metric(dst, metric));
 131 }
 132
 133 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric,
 134                                       unsigned long rtt)
 135 {
 136         dst->metrics[metric-1] = jiffies_to_msecs(rtt);
 137 }
 138
 139 static inline u32
 140 dst_allfrag(const struct dst_entry *dst)
 141 {
 142         int ret = dst_feature(dst,  RTAX_FEATURE_ALLFRAG);
 143         /* Yes, _exactly_. This is paranoia. */
 144         barrier();
 145         return ret;
 146 }
 147
 148 static inline int
 149 dst_metric_locked(struct dst_entry *dst, int metric)
 150 {
 151         return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 152 }
 153
 154 static inline void dst_hold(struct dst_entry * dst)
 155 {
 156         /*
 157          * If your kernel compilation stops here, please check
 158          * __pad_to_align_refcnt declaration in struct dst_entry
 159          */
 160         BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
 161         atomic_inc(&dst->__refcnt);
 162 }
 163
 164 static inline void dst_use(struct dst_entry *dst, unsigned long time)
 165 {
 166         dst_hold(dst);
 167         dst->__use++;
 168         dst->lastuse = time;
 169 }
 170
 171 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
 172 {
 173         dst->__use++;
 174         dst->lastuse = time;
 175 }
 176
 177 static inline
 178 struct dst_entry * dst_clone(struct dst_entry * dst)
 179 {
 180         if (dst)
 181                 atomic_inc(&dst->__refcnt);
 182         return dst;
 183 }
 184
 185 extern void dst_release(struct dst_entry *dst);
 186
 187 static inline void refdst_drop(unsigned long refdst)
 188 {
 189         if (!(refdst & SKB_DST_NOREF))
 190                 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
 191 }
 192
 193 /**
 194  * skb_dst_drop - drops skb dst
 195  * @skb: buffer
 196  *
 197  * Drops dst reference count if a reference was taken.
 198  */
 199 static inline void skb_dst_drop(struct sk_buff *skb)
 200 {
 201         if (skb->_skb_refdst) {
 202                 refdst_drop(skb->_skb_refdst);
 203                 skb->_skb_refdst = 0UL;
 204         }
 205 }
 206
 207 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
 208 {
 209         nskb->_skb_refdst = oskb->_skb_refdst;
 210         if (!(nskb->_skb_refdst & SKB_DST_NOREF))
 211                 dst_clone(skb_dst(nskb));
 212 }
 213
 214 /**
 215  * skb_dst_force - makes sure skb dst is refcounted
 216  * @skb: buffer
 217  *
 218  * If dst is not yet refcounted, let's do it
 219  */
 220 static inline void skb_dst_force(struct sk_buff *skb)
 221 {
 222         if (skb_dst_is_noref(skb)) {
 223                 WARN_ON(!rcu_read_lock_held());
 224                 skb->_skb_refdst &= ~SKB_DST_NOREF;
 225                 dst_clone(skb_dst(skb));
 226         }
 227 }
 228
 229
 230 /**
 231  *      skb_tunnel_rx - prepare skb for rx reinsert
 232  *      @skb: buffer
 233  *      @dev: tunnel device
 234  *
 235  *      After decapsulation, packet is going to re-enter (netif_rx()) our stack,
 236  *      so make some cleanups, and perform accounting.
 237  */
 238 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev)
 239 {
 240         skb->dev = dev;
 241         /* TODO : stats should be SMP safe */
 242         dev->stats.rx_packets++;
 243         dev->stats.rx_bytes += skb->len;
 244         skb->rxhash = 0;
 245         skb_dst_drop(skb);
 246         nf_reset(skb);
 247 }
 248
 249 /* Children define the path of the packet through the
 250  * Linux networking.  Thus, destinations are stackable.
 251  */
 252
 253 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb)
 254 {
 255         struct dst_entry *child = skb_dst(skb)->child;
 256
 257         skb_dst_drop(skb);
 258         return child;
 259 }
 260
 261 extern int dst_discard(struct sk_buff *skb);
 262 extern void * dst_alloc(struct dst_ops * ops);
 263 extern void __dst_free(struct dst_entry * dst);
 264 extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 265
 266 static inline void dst_free(struct dst_entry * dst)
 267 {
 268         if (dst->obsolete > 1)
 269                 return;
 270         if (!atomic_read(&dst->__refcnt)) {
 271                 dst = dst_destroy(dst);
 272                 if (!dst)
 273                         return;
 274         }
 275         __dst_free(dst);
 276 }
 277
 278 static inline void dst_rcu_free(struct rcu_head *head)
 279 {
 280         struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
 281         dst_free(dst);
 282 }
 283
 284 static inline void dst_confirm(struct dst_entry *dst)
 285 {
 286         if (dst)
 287                 neigh_confirm(dst->neighbour);
 288 }
 289
 290 static inline void dst_link_failure(struct sk_buff *skb)
 291 {
 292         struct dst_entry *dst = skb_dst(skb);
 293         if (dst && dst->ops && dst->ops->link_failure)
 294                 dst->ops->link_failure(skb);
 295 }
 296
 297 static inline void dst_set_expires(struct dst_entry *dst, int timeout)
 298 {
 299         unsigned long expires = jiffies + timeout;
 300
 301         if (expires == 0)
 302                 expires = 1;
 303
 304         if (dst->expires == 0 || time_before(expires, dst->expires))
 305                 dst->expires = expires;
 306 }
 307
 308 /* Output packet to network from transport.  */
 309 static inline int dst_output(struct sk_buff *skb)
 310 {
 311         return skb_dst(skb)->output(skb);
 312 }
 313
 314 /* Input packet from network to transport.  */
 315 static inline int dst_input(struct sk_buff *skb)
 316 {
 317         return skb_dst(skb)->input(skb);
 318 }
 319
 320 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
 321 {
 322         if (dst->obsolete)
 323                 dst = dst->ops->check(dst, cookie);
 324         return dst;
 325 }
 326
 327 extern void             dst_init(void);
 328
 329 /* Flags for xfrm_lookup flags argument. */
 330 enum {
 331         XFRM_LOOKUP_WAIT = 1 << 0,
 332         XFRM_LOOKUP_ICMP = 1 << 1,
 333 };
 334
 335 struct flowi;
 336 #ifndef CONFIG_XFRM
 337 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 338                               struct flowi *fl, struct sock *sk, int flags)
 339 {
 340         return 0;
 341 }
 342 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 343                                 struct flowi *fl, struct sock *sk, int flags)
 344 {
 345         return 0;
 346 }
 347 #else
 348 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 349                        struct flowi *fl, struct sock *sk, int flags);
 350 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 351                          struct flowi *fl, struct sock *sk, int flags);
 352 #endif
 353 #endif
 354
 355 #endif /* _NET_DST_H */