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 u32 metrics[RTAX_MAX]; 56 struct dst_entry *path; 57 58 unsigned long rate_last; /* rate limiting for ICMP */ 59 unsigned int rate_tokens; 60 61 #ifdef CONFIG_NET_CLS_ROUTE 62 __u32 tclassid; 63 #endif 64 65 struct neighbour *neighbour; 66 struct hh_cache *hh; 67 struct xfrm_state *xfrm; 68 69 int (*input)(struct sk_buff*); 70 int (*output)(struct sk_buff*); 71 72 struct dst_ops *ops; 73 74 unsigned long lastuse; 75 atomic_t __refcnt; /* client references */ 76 int __use; 77 union { 78 struct dst_entry *next; 79 struct rtable *rt_next; 80 struct rt6_info *rt6_next; 81 struct dn_route *dn_next; 82 }; 83 }; 84 85 86 struct dst_ops 87 { 88 unsigned short family; 89 __be16 protocol; 90 unsigned gc_thresh; 91 92 int (*gc)(struct dst_ops *ops); 93 struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); 94 void (*destroy)(struct dst_entry *); 95 void (*ifdown)(struct dst_entry *, 96 struct net_device *dev, int how); 97 struct dst_entry * (*negative_advice)(struct dst_entry *); 98 void (*link_failure)(struct sk_buff *); 99 void (*update_pmtu)(struct dst_entry *dst, u32 mtu); 100 int (*local_out)(struct sk_buff *skb); 101 int entry_size; 102 103 atomic_t entries; 104 struct kmem_cache *kmem_cachep; 105 struct net *dst_net; 106 }; 107 108 #ifdef __KERNEL__ 109 110 static inline u32 111 dst_metric(const struct dst_entry *dst, int metric) 112 { 113 return dst->metrics[metric-1]; 114 } 115 116 static inline u32 dst_mtu(const struct dst_entry *dst) 117 { 118 u32 mtu = dst_metric(dst, RTAX_MTU); 119 /* 120 * Alexey put it here, so ask him about it :) 121 */ 122 barrier(); 123 return mtu; 124 } 125 126 static inline u32 127 dst_allfrag(const struct dst_entry *dst) 128 { 129 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG; 130 /* Yes, _exactly_. This is paranoia. */ 131 barrier(); 132 return ret; 133 } 134 135 static inline int 136 dst_metric_locked(struct dst_entry *dst, int metric) 137 { 138 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 139 } 140 141 static inline void dst_hold(struct dst_entry * dst) 142 { 143 atomic_inc(&dst->__refcnt); 144 } 145 146 static inline void dst_use(struct dst_entry *dst, unsigned long time) 147 { 148 dst_hold(dst); 149 dst->__use++; 150 dst->lastuse = time; 151 } 152 153 static inline 154 struct dst_entry * dst_clone(struct dst_entry * dst) 155 { 156 if (dst) 157 atomic_inc(&dst->__refcnt); 158 return dst; 159 } 160 161 static inline 162 void dst_release(struct dst_entry * dst) 163 { 164 if (dst) { 165 WARN_ON(atomic_read(&dst->__refcnt) < 1); 166 smp_mb__before_atomic_dec(); 167 atomic_dec(&dst->__refcnt); 168 } 169 } 170 171 /* Children define the path of the packet through the 172 * Linux networking. Thus, destinations are stackable. 173 */ 174 175 static inline struct dst_entry *dst_pop(struct dst_entry *dst) 176 { 177 struct dst_entry *child = dst_clone(dst->child); 178 179 dst_release(dst); 180 return child; 181 } 182 183 extern int dst_discard(struct sk_buff *skb); 184 extern void * dst_alloc(struct dst_ops * ops); 185 extern void __dst_free(struct dst_entry * dst); 186 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 187 188 static inline void dst_free(struct dst_entry * dst) 189 { 190 if (dst->obsolete > 1) 191 return; 192 if (!atomic_read(&dst->__refcnt)) { 193 dst = dst_destroy(dst); 194 if (!dst) 195 return; 196 } 197 __dst_free(dst); 198 } 199 200 static inline void dst_rcu_free(struct rcu_head *head) 201 { 202 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 203 dst_free(dst); 204 } 205 206 static inline void dst_confirm(struct dst_entry *dst) 207 { 208 if (dst) 209 neigh_confirm(dst->neighbour); 210 } 211 212 static inline void dst_negative_advice(struct dst_entry **dst_p) 213 { 214 struct dst_entry * dst = *dst_p; 215 if (dst && dst->ops->negative_advice) 216 *dst_p = dst->ops->negative_advice(dst); 217 } 218 219 static inline void dst_link_failure(struct sk_buff *skb) 220 { 221 struct dst_entry * dst = skb->dst; 222 if (dst && dst->ops && dst->ops->link_failure) 223 dst->ops->link_failure(skb); 224 } 225 226 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 227 { 228 unsigned long expires = jiffies + timeout; 229 230 if (expires == 0) 231 expires = 1; 232 233 if (dst->expires == 0 || time_before(expires, dst->expires)) 234 dst->expires = expires; 235 } 236 237 /* Output packet to network from transport. */ 238 static inline int dst_output(struct sk_buff *skb) 239 { 240 return skb->dst->output(skb); 241 } 242 243 /* Input packet from network to transport. */ 244 static inline int dst_input(struct sk_buff *skb) 245 { 246 int err; 247 248 for (;;) { 249 err = skb->dst->input(skb); 250 251 if (likely(err == 0)) 252 return err; 253 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */ 254 if (unlikely(err != NET_XMIT_BYPASS)) 255 return err; 256 } 257 } 258 259 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 260 { 261 if (dst->obsolete) 262 dst = dst->ops->check(dst, cookie); 263 return dst; 264 } 265 266 extern void dst_init(void); 267 268 /* Flags for xfrm_lookup flags argument. */ 269 enum { 270 XFRM_LOOKUP_WAIT = 1 << 0, 271 XFRM_LOOKUP_ICMP = 1 << 1, 272 }; 273 274 struct flowi; 275 #ifndef CONFIG_XFRM 276 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 277 struct sock *sk, int flags) 278 { 279 return 0; 280 } 281 static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 282 struct sock *sk, int flags) 283 { 284 return 0; 285 } 286 #else 287 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 288 struct sock *sk, int flags); 289 extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 290 struct sock *sk, int flags); 291 #endif 292 #endif 293 294 #endif /* _NET_DST_H */ 295