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 nfheader_len; /* more non-fragment space at head required */ 54 unsigned short trailer_len; /* space to reserve at tail */ 55 56 u32 metrics[RTAX_MAX]; 57 struct dst_entry *path; 58 59 unsigned long rate_last; /* rate limiting for ICMP */ 60 unsigned long rate_tokens; 61 62 struct neighbour *neighbour; 63 struct hh_cache *hh; 64 struct xfrm_state *xfrm; 65 66 int (*input)(struct sk_buff*); 67 int (*output)(struct sk_buff*); 68 69 #ifdef CONFIG_NET_CLS_ROUTE 70 __u32 tclassid; 71 #endif 72 73 struct dst_ops *ops; 74 75 unsigned long lastuse; 76 atomic_t __refcnt; /* client references */ 77 int __use; 78 union { 79 struct dst_entry *next; 80 struct rtable *rt_next; 81 struct rt6_info *rt6_next; 82 struct dn_route *dn_next; 83 }; 84 char info[0]; 85 }; 86 87 88 struct dst_ops 89 { 90 unsigned short family; 91 __be16 protocol; 92 unsigned gc_thresh; 93 94 int (*gc)(void); 95 struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); 96 void (*destroy)(struct dst_entry *); 97 void (*ifdown)(struct dst_entry *, 98 struct net_device *dev, int how); 99 struct dst_entry * (*negative_advice)(struct dst_entry *); 100 void (*link_failure)(struct sk_buff *); 101 void (*update_pmtu)(struct dst_entry *dst, u32 mtu); 102 int entry_size; 103 104 atomic_t entries; 105 struct kmem_cache *kmem_cachep; 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 void * dst_alloc(struct dst_ops * ops); 184 extern void __dst_free(struct dst_entry * dst); 185 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 186 187 static inline void dst_free(struct dst_entry * dst) 188 { 189 if (dst->obsolete > 1) 190 return; 191 if (!atomic_read(&dst->__refcnt)) { 192 dst = dst_destroy(dst); 193 if (!dst) 194 return; 195 } 196 __dst_free(dst); 197 } 198 199 static inline void dst_rcu_free(struct rcu_head *head) 200 { 201 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 202 dst_free(dst); 203 } 204 205 static inline void dst_confirm(struct dst_entry *dst) 206 { 207 if (dst) 208 neigh_confirm(dst->neighbour); 209 } 210 211 static inline void dst_negative_advice(struct dst_entry **dst_p) 212 { 213 struct dst_entry * dst = *dst_p; 214 if (dst && dst->ops->negative_advice) 215 *dst_p = dst->ops->negative_advice(dst); 216 } 217 218 static inline void dst_link_failure(struct sk_buff *skb) 219 { 220 struct dst_entry * dst = skb->dst; 221 if (dst && dst->ops && dst->ops->link_failure) 222 dst->ops->link_failure(skb); 223 } 224 225 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 226 { 227 unsigned long expires = jiffies + timeout; 228 229 if (expires == 0) 230 expires = 1; 231 232 if (dst->expires == 0 || time_before(expires, dst->expires)) 233 dst->expires = expires; 234 } 235 236 /* Output packet to network from transport. */ 237 static inline int dst_output(struct sk_buff *skb) 238 { 239 return skb->dst->output(skb); 240 } 241 242 /* Input packet from network to transport. */ 243 static inline int dst_input(struct sk_buff *skb) 244 { 245 int err; 246 247 for (;;) { 248 err = skb->dst->input(skb); 249 250 if (likely(err == 0)) 251 return err; 252 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */ 253 if (unlikely(err != NET_XMIT_BYPASS)) 254 return err; 255 } 256 } 257 258 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 259 { 260 if (dst->obsolete) 261 dst = dst->ops->check(dst, cookie); 262 return dst; 263 } 264 265 extern void dst_init(void); 266 267 struct flowi; 268 #ifndef CONFIG_XFRM 269 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 270 struct sock *sk, int flags) 271 { 272 return 0; 273 } 274 static inline int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 275 struct sock *sk, int flags) 276 { 277 return 0; 278 } 279 #else 280 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 281 struct sock *sk, int flags); 282 extern int __xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 283 struct sock *sk, int flags); 284 #endif 285 #endif 286 287 #endif /* _NET_DST_H */ 288