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 <net/dst_ops.h> 12 #include <linux/netdevice.h> 13 #include <linux/rtnetlink.h> 14 #include <linux/rcupdate.h> 15 #include <linux/jiffies.h> 16 #include <net/neighbour.h> 17 #include <asm/processor.h> 18 19 /* 20 * 0 - no debugging messages 21 * 1 - rare events and bugs (default) 22 * 2 - trace mode. 23 */ 24 #define RT_CACHE_DEBUG 0 25 26 #define DST_GC_MIN (HZ/10) 27 #define DST_GC_INC (HZ/2) 28 #define DST_GC_MAX (120*HZ) 29 30 /* Each dst_entry has reference count and sits in some parent list(s). 31 * When it is removed from parent list, it is "freed" (dst_free). 32 * After this it enters dead state (dst->obsolete > 0) and if its refcnt 33 * is zero, it can be destroyed immediately, otherwise it is added 34 * to gc list and garbage collector periodically checks the refcnt. 35 */ 36 37 struct sk_buff; 38 39 struct dst_entry { 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 unsigned int rate_tokens; 56 unsigned long rate_last; /* rate limiting for ICMP */ 57 58 struct dst_entry *path; 59 60 struct neighbour *neighbour; 61 struct hh_cache *hh; 62 #ifdef CONFIG_XFRM 63 struct xfrm_state *xfrm; 64 #else 65 void *__pad1; 66 #endif 67 int (*input)(struct sk_buff*); 68 int (*output)(struct sk_buff*); 69 70 struct dst_ops *ops; 71 72 u32 metrics[RTAX_MAX]; 73 74 #ifdef CONFIG_NET_CLS_ROUTE 75 __u32 tclassid; 76 #else 77 __u32 __pad2; 78 #endif 79 80 81 /* 82 * Align __refcnt to a 64 bytes alignment 83 * (L1_CACHE_SIZE would be too much) 84 */ 85 #ifdef CONFIG_64BIT 86 long __pad_to_align_refcnt[2]; 87 #else 88 long __pad_to_align_refcnt[1]; 89 #endif 90 /* 91 * __refcnt wants to be on a different cache line from 92 * input/output/ops or performance tanks badly 93 */ 94 atomic_t __refcnt; /* client references */ 95 int __use; 96 unsigned long lastuse; 97 union { 98 struct dst_entry *next; 99 struct rtable *rt_next; 100 struct rt6_info *rt6_next; 101 struct dn_route *dn_next; 102 }; 103 }; 104 105 #ifdef __KERNEL__ 106 107 static inline u32 108 dst_metric(const struct dst_entry *dst, int metric) 109 { 110 return dst->metrics[metric-1]; 111 } 112 113 static inline u32 114 dst_feature(const struct dst_entry *dst, u32 feature) 115 { 116 return dst_metric(dst, RTAX_FEATURES) & feature; 117 } 118 119 static inline u32 dst_mtu(const struct dst_entry *dst) 120 { 121 u32 mtu = dst_metric(dst, RTAX_MTU); 122 /* 123 * Alexey put it here, so ask him about it :) 124 */ 125 barrier(); 126 return mtu; 127 } 128 129 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 130 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 131 { 132 return msecs_to_jiffies(dst_metric(dst, metric)); 133 } 134 135 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric, 136 unsigned long rtt) 137 { 138 dst->metrics[metric-1] = jiffies_to_msecs(rtt); 139 } 140 141 static inline u32 142 dst_allfrag(const struct dst_entry *dst) 143 { 144 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 145 /* Yes, _exactly_. This is paranoia. */ 146 barrier(); 147 return ret; 148 } 149 150 static inline int 151 dst_metric_locked(struct dst_entry *dst, int metric) 152 { 153 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 154 } 155 156 static inline void dst_hold(struct dst_entry * dst) 157 { 158 /* 159 * If your kernel compilation stops here, please check 160 * __pad_to_align_refcnt declaration in struct dst_entry 161 */ 162 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 163 atomic_inc(&dst->__refcnt); 164 } 165 166 static inline void dst_use(struct dst_entry *dst, unsigned long time) 167 { 168 dst_hold(dst); 169 dst->__use++; 170 dst->lastuse = time; 171 } 172 173 static inline 174 struct dst_entry * dst_clone(struct dst_entry * dst) 175 { 176 if (dst) 177 atomic_inc(&dst->__refcnt); 178 return dst; 179 } 180 181 extern void dst_release(struct dst_entry *dst); 182 static inline void skb_dst_drop(struct sk_buff *skb) 183 { 184 if (skb->_skb_dst) 185 dst_release(skb_dst(skb)); 186 skb->_skb_dst = 0UL; 187 } 188 189 /* Children define the path of the packet through the 190 * Linux networking. Thus, destinations are stackable. 191 */ 192 193 static inline struct dst_entry *dst_pop(struct dst_entry *dst) 194 { 195 struct dst_entry *child = dst_clone(dst->child); 196 197 dst_release(dst); 198 return child; 199 } 200 201 extern int dst_discard(struct sk_buff *skb); 202 extern void * dst_alloc(struct dst_ops * ops); 203 extern void __dst_free(struct dst_entry * dst); 204 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 205 206 static inline void dst_free(struct dst_entry * dst) 207 { 208 if (dst->obsolete > 1) 209 return; 210 if (!atomic_read(&dst->__refcnt)) { 211 dst = dst_destroy(dst); 212 if (!dst) 213 return; 214 } 215 __dst_free(dst); 216 } 217 218 static inline void dst_rcu_free(struct rcu_head *head) 219 { 220 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 221 dst_free(dst); 222 } 223 224 static inline void dst_confirm(struct dst_entry *dst) 225 { 226 if (dst) 227 neigh_confirm(dst->neighbour); 228 } 229 230 static inline void dst_negative_advice(struct dst_entry **dst_p, 231 struct sock *sk) 232 { 233 struct dst_entry * dst = *dst_p; 234 if (dst && dst->ops->negative_advice) { 235 *dst_p = dst->ops->negative_advice(dst); 236 237 if (dst != *dst_p) { 238 extern void sk_reset_txq(struct sock *sk); 239 240 sk_reset_txq(sk); 241 } 242 } 243 } 244 245 static inline void dst_link_failure(struct sk_buff *skb) 246 { 247 struct dst_entry *dst = skb_dst(skb); 248 if (dst && dst->ops && dst->ops->link_failure) 249 dst->ops->link_failure(skb); 250 } 251 252 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 253 { 254 unsigned long expires = jiffies + timeout; 255 256 if (expires == 0) 257 expires = 1; 258 259 if (dst->expires == 0 || time_before(expires, dst->expires)) 260 dst->expires = expires; 261 } 262 263 /* Output packet to network from transport. */ 264 static inline int dst_output(struct sk_buff *skb) 265 { 266 return skb_dst(skb)->output(skb); 267 } 268 269 /* Input packet from network to transport. */ 270 static inline int dst_input(struct sk_buff *skb) 271 { 272 return skb_dst(skb)->input(skb); 273 } 274 275 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 276 { 277 if (dst->obsolete) 278 dst = dst->ops->check(dst, cookie); 279 return dst; 280 } 281 282 extern void dst_init(void); 283 284 /* Flags for xfrm_lookup flags argument. */ 285 enum { 286 XFRM_LOOKUP_WAIT = 1 << 0, 287 XFRM_LOOKUP_ICMP = 1 << 1, 288 }; 289 290 struct flowi; 291 #ifndef CONFIG_XFRM 292 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 293 struct flowi *fl, struct sock *sk, int flags) 294 { 295 return 0; 296 } 297 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 298 struct flowi *fl, struct sock *sk, int flags) 299 { 300 return 0; 301 } 302 #else 303 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 304 struct flowi *fl, struct sock *sk, int flags); 305 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 306 struct flowi *fl, struct sock *sk, int flags); 307 #endif 308 #endif 309 310 #endif /* _NET_DST_H */ 311