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 (*get_mss)(struct dst_entry *dst, u32 mtu); 98 int entry_size; 99 100 atomic_t entries; 101 kmem_cache_t *kmem_cachep; 102 }; 103 104 #ifdef __KERNEL__ 105 106 static inline u32 107 dst_metric(const struct dst_entry *dst, int metric) 108 { 109 return dst->metrics[metric-1]; 110 } 111 112 static inline u32 dst_mtu(const struct dst_entry *dst) 113 { 114 u32 mtu = dst_metric(dst, RTAX_MTU); 115 /* 116 * Alexey put it here, so ask him about it :) 117 */ 118 barrier(); 119 return mtu; 120 } 121 122 static inline u32 123 dst_allfrag(const struct dst_entry *dst) 124 { 125 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG; 126 /* Yes, _exactly_. This is paranoia. */ 127 barrier(); 128 return ret; 129 } 130 131 static inline int 132 dst_metric_locked(struct dst_entry *dst, int metric) 133 { 134 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 135 } 136 137 static inline void dst_hold(struct dst_entry * dst) 138 { 139 atomic_inc(&dst->__refcnt); 140 } 141 142 static inline 143 struct dst_entry * dst_clone(struct dst_entry * dst) 144 { 145 if (dst) 146 atomic_inc(&dst->__refcnt); 147 return dst; 148 } 149 150 static inline 151 void dst_release(struct dst_entry * dst) 152 { 153 if (dst) { 154 WARN_ON(atomic_read(&dst->__refcnt) < 1); 155 smp_mb__before_atomic_dec(); 156 atomic_dec(&dst->__refcnt); 157 } 158 } 159 160 /* Children define the path of the packet through the 161 * Linux networking. Thus, destinations are stackable. 162 */ 163 164 static inline struct dst_entry *dst_pop(struct dst_entry *dst) 165 { 166 struct dst_entry *child = dst_clone(dst->child); 167 168 dst_release(dst); 169 return child; 170 } 171 172 extern void * dst_alloc(struct dst_ops * ops); 173 extern void __dst_free(struct dst_entry * dst); 174 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 175 176 static inline void dst_free(struct dst_entry * dst) 177 { 178 if (dst->obsolete > 1) 179 return; 180 if (!atomic_read(&dst->__refcnt)) { 181 dst = dst_destroy(dst); 182 if (!dst) 183 return; 184 } 185 __dst_free(dst); 186 } 187 188 static inline void dst_rcu_free(struct rcu_head *head) 189 { 190 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 191 dst_free(dst); 192 } 193 194 static inline void dst_confirm(struct dst_entry *dst) 195 { 196 if (dst) 197 neigh_confirm(dst->neighbour); 198 } 199 200 static inline void dst_negative_advice(struct dst_entry **dst_p) 201 { 202 struct dst_entry * dst = *dst_p; 203 if (dst && dst->ops->negative_advice) 204 *dst_p = dst->ops->negative_advice(dst); 205 } 206 207 static inline void dst_link_failure(struct sk_buff *skb) 208 { 209 struct dst_entry * dst = skb->dst; 210 if (dst && dst->ops && dst->ops->link_failure) 211 dst->ops->link_failure(skb); 212 } 213 214 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 215 { 216 unsigned long expires = jiffies + timeout; 217 218 if (expires == 0) 219 expires = 1; 220 221 if (dst->expires == 0 || time_before(expires, dst->expires)) 222 dst->expires = expires; 223 } 224 225 /* Output packet to network from transport. */ 226 static inline int dst_output(struct sk_buff *skb) 227 { 228 int err; 229 230 for (;;) { 231 err = skb->dst->output(skb); 232 233 if (likely(err == 0)) 234 return err; 235 if (unlikely(err != NET_XMIT_BYPASS)) 236 return err; 237 } 238 } 239 240 /* Input packet from network to transport. */ 241 static inline int dst_input(struct sk_buff *skb) 242 { 243 int err; 244 245 for (;;) { 246 err = skb->dst->input(skb); 247 248 if (likely(err == 0)) 249 return err; 250 /* Oh, Jamal... Seems, I will not forgive you this mess. :-) */ 251 if (unlikely(err != NET_XMIT_BYPASS)) 252 return err; 253 } 254 } 255 256 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 257 { 258 if (dst->obsolete) 259 dst = dst->ops->check(dst, cookie); 260 return dst; 261 } 262 263 extern void dst_init(void); 264 265 struct flowi; 266 #ifndef CONFIG_XFRM 267 static inline int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 268 struct sock *sk, int flags) 269 { 270 return 0; 271 } 272 #else 273 extern int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 274 struct sock *sk, int flags); 275 #endif 276 #endif 277 278 #endif /* _NET_DST_H */ 279