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/config.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 dst_entry *next; 41 atomic_t __refcnt; /* client references */ 42 int __use; 43 struct dst_entry *child; 44 struct net_device *dev; 45 short error; 46 short obsolete; 47 int flags; 48 #define DST_HOST 1 49 #define DST_NOXFRM 2 50 #define DST_NOPOLICY 4 51 #define DST_NOHASH 8 52 #define DST_BALANCED 0x10 53 unsigned long lastuse; 54 unsigned long expires; 55 56 unsigned short header_len; /* more space at head required */ 57 unsigned short trailer_len; /* space to reserve at tail */ 58 59 u32 metrics[RTAX_MAX]; 60 struct dst_entry *path; 61 62 unsigned long rate_last; /* rate limiting for ICMP */ 63 unsigned long rate_tokens; 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 #ifdef CONFIG_NET_CLS_ROUTE 73 __u32 tclassid; 74 #endif 75 76 struct dst_ops *ops; 77 struct rcu_head rcu_head; 78 79 char info[0]; 80 }; 81 82 83 struct dst_ops 84 { 85 unsigned short family; 86 unsigned short protocol; 87 unsigned gc_thresh; 88 89 int (*gc)(void); 90 struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); 91 void (*destroy)(struct dst_entry *); 92 void (*ifdown)(struct dst_entry *, 93 struct net_device *dev, int how); 94 struct dst_entry * (*negative_advice)(struct dst_entry *); 95 void (*link_failure)(struct sk_buff *); 96 void (*update_pmtu)(struct dst_entry *dst, u32 mtu); 97 int entry_size; 98 99 atomic_t entries; 100 kmem_cache_t *kmem_cachep; 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 dst_mtu(const struct dst_entry *dst) 112 { 113 u32 mtu = dst_metric(dst, RTAX_MTU); 114 /* 115 * Alexey put it here, so ask him about it :) 116 */ 117 barrier(); 118 return mtu; 119 } 120 121 static inline u32 122 dst_allfrag(const struct dst_entry *dst) 123 { 124 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG; 125 /* Yes, _exactly_. This is paranoia. */ 126 barrier(); 127 return ret; 128 } 129 130 static inline int 131 dst_metric_locked(struct dst_entry *dst, int metric) 132 { 133 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 134 } 135 136 static inline void dst_hold(struct dst_entry * dst) 137 { 138 atomic_inc(&dst->__refcnt); 139 } 140 141 static inline 142 struct dst_entry * dst_clone(struct dst_entry * dst) 143 { 144 if (dst) 145 atomic_inc(&dst->__refcnt); 146 return dst; 147 } 148 149 static inline 150 void dst_release(struct dst_entry * dst) 151 { 152 if (dst) { 153 WARN_ON(atomic_read(&dst->__refcnt) < 1); 154 smp_mb__before_atomic_dec(); 155 atomic_dec(&dst->__refcnt); 156 } 157 } 158 159 /* Children define the path of the packet through the 160 * Linux networking. Thus, destinations are stackable. 161 */ 162 163 static inline struct dst_entry *dst_pop(struct dst_entry *dst) 164 { 165 struct dst_entry *child = dst_clone(dst->child); 166 167 dst_release(dst); 168 return child; 169 } 170 171 extern void * dst_alloc(struct dst_ops * ops); 172 extern void __dst_free(struct dst_entry * dst); 173 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 174 175 static inline void dst_free(struct dst_entry * dst) 176 { 177 if (dst->obsolete > 1) 178 return; 179 if (!atomic_read(&dst->__refcnt)) { 180 dst = dst_destroy(dst); 181 if (!dst) 182 return; 183 } 184 __dst_free(dst); 185 } 186 187 static inline void dst_rcu_free(struct rcu_head *head) 188 { 189 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 190 dst_free(dst); 191 } 192 193 static inline void dst_confirm(struct dst_entry *dst) 194 { 195 if (dst) 196 neigh_confirm(dst->neighbour); 197 } 198 199 static inline void dst_negative_advice(struct dst_entry **dst_p) 200 { 201 struct dst_entry * dst = *dst_p; 202 if (dst && dst->ops->negative_advice) 203 *dst_p = dst->ops->negative_advice(dst); 204 } 205 206 static inline void dst_link_failure(struct sk_buff *skb) 207 { 208 struct dst_entry * dst = skb->dst; 209 if (dst && dst->ops && dst->ops->link_failure) 210 dst->ops->link_failure(skb); 211 } 212 213 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 214 { 215 unsigned long expires = jiffies + timeout; 216 217 if (expires == 0) 218 expires = 1; 219 220 if (dst->expires == 0 || time_before(expires, dst->expires)) 221 dst->expires = expires; 222 } 223 224 /* Output packet to network from transport. */ 225 static inline int dst_output(struct sk_buff *skb) 226 { 227 int err; 228 229 for (;;) { 230 err = skb->dst->output(skb); 231 232 if (likely(err == 0)) 233 return err; 234 if (unlikely(err != NET_XMIT_BYPASS)) 235 return err; 236 } 237 } 238 239 /* Input packet from network to transport. */ 240 static inline int dst_input(struct sk_buff *skb) 241 { 242 int err; 243 244 for (;;) { 245 err = skb->dst->input(skb); 246 247 if (likely(err == 0)) 248 return err; 249 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */ 250 if (unlikely(err != NET_XMIT_BYPASS)) 251 return err; 252 } 253 } 254 255 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 256 { 257 if (dst->obsolete) 258 dst = dst->ops->check(dst, cookie); 259 return dst; 260 } 261 262 extern void dst_init(void); 263 264 struct flowi; 265 #ifndef CONFIG_XFRM 266 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 267 struct sock *sk, int flags) 268 { 269 return 0; 270 } 271 #else 272 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 273 struct sock *sk, int flags); 274 #endif 275 #endif 276 277 #endif /* _NET_DST_H */ 278