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 #define DST_BALANCED 0x10 51 unsigned long expires; 52 53 unsigned short header_len; /* more space at head required */ 54 unsigned short nfheader_len; /* more non-fragment space at head required */ 55 unsigned short trailer_len; /* space to reserve at tail */ 56 57 u32 metrics[RTAX_MAX]; 58 struct dst_entry *path; 59 60 unsigned long rate_last; /* rate limiting for ICMP */ 61 unsigned long rate_tokens; 62 63 struct neighbour *neighbour; 64 struct hh_cache *hh; 65 struct xfrm_state *xfrm; 66 67 int (*input)(struct sk_buff*); 68 int (*output)(struct sk_buff*); 69 70 #ifdef CONFIG_NET_CLS_ROUTE 71 __u32 tclassid; 72 #endif 73 74 struct dst_ops *ops; 75 76 unsigned long lastuse; 77 atomic_t __refcnt; /* client references */ 78 int __use; 79 union { 80 struct dst_entry *next; 81 struct rtable *rt_next; 82 struct rt6_info *rt6_next; 83 struct dn_route *dn_next; 84 }; 85 char info[0]; 86 }; 87 88 89 struct dst_ops 90 { 91 unsigned short family; 92 __be16 protocol; 93 unsigned gc_thresh; 94 95 int (*gc)(void); 96 struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); 97 void (*destroy)(struct dst_entry *); 98 void (*ifdown)(struct dst_entry *, 99 struct net_device *dev, int how); 100 struct dst_entry * (*negative_advice)(struct dst_entry *); 101 void (*link_failure)(struct sk_buff *); 102 void (*update_pmtu)(struct dst_entry *dst, u32 mtu); 103 int entry_size; 104 105 atomic_t entries; 106 struct kmem_cache *kmem_cachep; 107 }; 108 109 #ifdef __KERNEL__ 110 111 static inline u32 112 dst_metric(const struct dst_entry *dst, int metric) 113 { 114 return dst->metrics[metric-1]; 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 static inline u32 128 dst_allfrag(const struct dst_entry *dst) 129 { 130 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG; 131 /* Yes, _exactly_. This is paranoia. */ 132 barrier(); 133 return ret; 134 } 135 136 static inline int 137 dst_metric_locked(struct dst_entry *dst, int metric) 138 { 139 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 140 } 141 142 static inline void dst_hold(struct dst_entry * dst) 143 { 144 atomic_inc(&dst->__refcnt); 145 } 146 147 static inline 148 struct dst_entry * dst_clone(struct dst_entry * dst) 149 { 150 if (dst) 151 atomic_inc(&dst->__refcnt); 152 return dst; 153 } 154 155 static inline 156 void dst_release(struct dst_entry * dst) 157 { 158 if (dst) { 159 WARN_ON(atomic_read(&dst->__refcnt) < 1); 160 smp_mb__before_atomic_dec(); 161 atomic_dec(&dst->__refcnt); 162 } 163 } 164 165 /* Children define the path of the packet through the 166 * Linux networking. Thus, destinations are stackable. 167 */ 168 169 static inline struct dst_entry *dst_pop(struct dst_entry *dst) 170 { 171 struct dst_entry *child = dst_clone(dst->child); 172 173 dst_release(dst); 174 return child; 175 } 176 177 extern void * dst_alloc(struct dst_ops * ops); 178 extern void __dst_free(struct dst_entry * dst); 179 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 180 181 static inline void dst_free(struct dst_entry * dst) 182 { 183 if (dst->obsolete > 1) 184 return; 185 if (!atomic_read(&dst->__refcnt)) { 186 dst = dst_destroy(dst); 187 if (!dst) 188 return; 189 } 190 __dst_free(dst); 191 } 192 193 static inline void dst_rcu_free(struct rcu_head *head) 194 { 195 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 196 dst_free(dst); 197 } 198 199 static inline void dst_confirm(struct dst_entry *dst) 200 { 201 if (dst) 202 neigh_confirm(dst->neighbour); 203 } 204 205 static inline void dst_negative_advice(struct dst_entry **dst_p) 206 { 207 struct dst_entry * dst = *dst_p; 208 if (dst && dst->ops->negative_advice) 209 *dst_p = dst->ops->negative_advice(dst); 210 } 211 212 static inline void dst_link_failure(struct sk_buff *skb) 213 { 214 struct dst_entry * dst = skb->dst; 215 if (dst && dst->ops && dst->ops->link_failure) 216 dst->ops->link_failure(skb); 217 } 218 219 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 220 { 221 unsigned long expires = jiffies + timeout; 222 223 if (expires == 0) 224 expires = 1; 225 226 if (dst->expires == 0 || time_before(expires, dst->expires)) 227 dst->expires = expires; 228 } 229 230 /* Output packet to network from transport. */ 231 static inline int dst_output(struct sk_buff *skb) 232 { 233 return skb->dst->output(skb); 234 } 235 236 /* Input packet from network to transport. */ 237 static inline int dst_input(struct sk_buff *skb) 238 { 239 int err; 240 241 for (;;) { 242 err = skb->dst->input(skb); 243 244 if (likely(err == 0)) 245 return err; 246 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */ 247 if (unlikely(err != NET_XMIT_BYPASS)) 248 return err; 249 } 250 } 251 252 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 253 { 254 if (dst->obsolete) 255 dst = dst->ops->check(dst, cookie); 256 return dst; 257 } 258 259 extern void dst_init(void); 260 261 struct flowi; 262 #ifndef CONFIG_XFRM 263 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 264 struct sock *sk, int flags) 265 { 266 return 0; 267 } 268 #else 269 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 270 struct sock *sk, int flags); 271 #endif 272 #endif 273 274 #endif /* _NET_DST_H */ 275