LXR linux/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
  37struct sk_buff;
  38
  39struct 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
 107static inline u32
 108dst_metric(const struct dst_entry *dst, int metric)
 109{
 110        return dst->metrics[metric-1];
 111}
 112
 113static inline u32
 114dst_feature(const struct dst_entry *dst, u32 feature)
 115{
 116        return dst_metric(dst, RTAX_FEATURES) & feature;
 117}
 118
 119static 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 */
 130static 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
 135static 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
 141static inline u32
 142dst_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
 150static inline int
 151dst_metric_locked(struct dst_entry *dst, int metric)
 152{
 153        return dst_metric(dst, RTAX_LOCK) & (1<<metric);
 154}
 155
 156static 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
 166static 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
 173static inline
 174struct dst_entry * dst_clone(struct dst_entry * dst)
 175{
 176        if (dst)
 177                atomic_inc(&dst->__refcnt);
 178        return dst;
 179}
 180
 181extern void dst_release(struct dst_entry *dst);
 182static 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
 193static 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
 201extern int dst_discard(struct sk_buff *skb);
 202extern void * dst_alloc(struct dst_ops * ops);
 203extern void __dst_free(struct dst_entry * dst);
 204extern struct dst_entry *dst_destroy(struct dst_entry * dst);
 205
 206static 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
 218static 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
 224static inline void dst_confirm(struct dst_entry *dst)
 225{
 226        if (dst)
 227                neigh_confirm(dst->neighbour);
 228}
 229
 230static 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
 245static 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
 252static 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.  */
 264static 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.  */
 270static inline int dst_input(struct sk_buff *skb)
 271{
 272        return skb_dst(skb)->input(skb);
 273}
 274
 275static 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
 282extern void             dst_init(void);
 283
 284/* Flags for xfrm_lookup flags argument. */
 285enum {
 286        XFRM_LOOKUP_WAIT = 1 << 0,
 287        XFRM_LOOKUP_ICMP = 1 << 1,
 288};
 289
 290struct flowi;
 291#ifndef CONFIG_XFRM
 292static 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} 
 297static 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
 303extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p,
 304                       struct flowi *fl, struct sock *sk, int flags);
 305extern 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 */
 311