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 0x0001 47 #define DST_NOXFRM 0x0002 48 #define DST_NOPOLICY 0x0004 49 #define DST_NOHASH 0x0008 50 #define DST_NOCACHE 0x0010 51 unsigned long expires; 52 53 unsigned short header_len; /* more space at head required */ 54 unsigned short trailer_len; /* space to reserve at tail */ 55 56 unsigned int rate_tokens; 57 unsigned long rate_last; /* rate limiting for ICMP */ 58 59 struct dst_entry *path; 60 61 struct neighbour *neighbour; 62 struct hh_cache *hh; 63 #ifdef CONFIG_XFRM 64 struct xfrm_state *xfrm; 65 #else 66 void *__pad1; 67 #endif 68 int (*input)(struct sk_buff*); 69 int (*output)(struct sk_buff*); 70 71 struct dst_ops *ops; 72 73 u32 metrics[RTAX_MAX]; 74 75 #ifdef CONFIG_NET_CLS_ROUTE 76 __u32 tclassid; 77 #else 78 __u32 __pad2; 79 #endif 80 81 82 /* 83 * Align __refcnt to a 64 bytes alignment 84 * (L1_CACHE_SIZE would be too much) 85 */ 86 #ifdef CONFIG_64BIT 87 long __pad_to_align_refcnt[1]; 88 #endif 89 /* 90 * __refcnt wants to be on a different cache line from 91 * input/output/ops or performance tanks badly 92 */ 93 atomic_t __refcnt; /* client references */ 94 int __use; 95 unsigned long lastuse; 96 union { 97 struct dst_entry *next; 98 struct rtable *rt_next; 99 struct rt6_info *rt6_next; 100 struct dn_route *dn_next; 101 }; 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 113 dst_feature(const struct dst_entry *dst, u32 feature) 114 { 115 return dst_metric(dst, RTAX_FEATURES) & feature; 116 } 117 118 static inline u32 dst_mtu(const struct dst_entry *dst) 119 { 120 u32 mtu = dst_metric(dst, RTAX_MTU); 121 /* 122 * Alexey put it here, so ask him about it :) 123 */ 124 barrier(); 125 return mtu; 126 } 127 128 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 129 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 130 { 131 return msecs_to_jiffies(dst_metric(dst, metric)); 132 } 133 134 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric, 135 unsigned long rtt) 136 { 137 dst->metrics[metric-1] = jiffies_to_msecs(rtt); 138 } 139 140 static inline u32 141 dst_allfrag(const struct dst_entry *dst) 142 { 143 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 144 /* Yes, _exactly_. This is paranoia. */ 145 barrier(); 146 return ret; 147 } 148 149 static inline int 150 dst_metric_locked(struct dst_entry *dst, int metric) 151 { 152 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 153 } 154 155 static inline void dst_hold(struct dst_entry * dst) 156 { 157 /* 158 * If your kernel compilation stops here, please check 159 * __pad_to_align_refcnt declaration in struct dst_entry 160 */ 161 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 162 atomic_inc(&dst->__refcnt); 163 } 164 165 static inline void dst_use(struct dst_entry *dst, unsigned long time) 166 { 167 dst_hold(dst); 168 dst->__use++; 169 dst->lastuse = time; 170 } 171 172 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 173 { 174 dst->__use++; 175 dst->lastuse = time; 176 } 177 178 static inline 179 struct dst_entry * dst_clone(struct dst_entry * dst) 180 { 181 if (dst) 182 atomic_inc(&dst->__refcnt); 183 return dst; 184 } 185 186 extern void dst_release(struct dst_entry *dst); 187 188 static inline void refdst_drop(unsigned long refdst) 189 { 190 if (!(refdst & SKB_DST_NOREF)) 191 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 192 } 193 194 /** 195 * skb_dst_drop - drops skb dst 196 * @skb: buffer 197 * 198 * Drops dst reference count if a reference was taken. 199 */ 200 static inline void skb_dst_drop(struct sk_buff *skb) 201 { 202 if (skb->_skb_refdst) { 203 refdst_drop(skb->_skb_refdst); 204 skb->_skb_refdst = 0UL; 205 } 206 } 207 208 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 209 { 210 nskb->_skb_refdst = oskb->_skb_refdst; 211 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 212 dst_clone(skb_dst(nskb)); 213 } 214 215 /** 216 * skb_dst_force - makes sure skb dst is refcounted 217 * @skb: buffer 218 * 219 * If dst is not yet refcounted, let's do it 220 */ 221 static inline void skb_dst_force(struct sk_buff *skb) 222 { 223 if (skb_dst_is_noref(skb)) { 224 WARN_ON(!rcu_read_lock_held()); 225 skb->_skb_refdst &= ~SKB_DST_NOREF; 226 dst_clone(skb_dst(skb)); 227 } 228 } 229 230 231 /** 232 * __skb_tunnel_rx - prepare skb for rx reinsert 233 * @skb: buffer 234 * @dev: tunnel device 235 * 236 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 237 * so make some cleanups. (no accounting done) 238 */ 239 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 240 { 241 skb->dev = dev; 242 skb->rxhash = 0; 243 skb_set_queue_mapping(skb, 0); 244 skb_dst_drop(skb); 245 nf_reset(skb); 246 } 247 248 /** 249 * skb_tunnel_rx - prepare skb for rx reinsert 250 * @skb: buffer 251 * @dev: tunnel device 252 * 253 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 254 * so make some cleanups, and perform accounting. 255 * Note: this accounting is not SMP safe. 256 */ 257 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 258 { 259 /* TODO : stats should be SMP safe */ 260 dev->stats.rx_packets++; 261 dev->stats.rx_bytes += skb->len; 262 __skb_tunnel_rx(skb, dev); 263 } 264 265 /* Children define the path of the packet through the 266 * Linux networking. Thus, destinations are stackable. 267 */ 268 269 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb) 270 { 271 struct dst_entry *child = skb_dst(skb)->child; 272 273 skb_dst_drop(skb); 274 return child; 275 } 276 277 extern int dst_discard(struct sk_buff *skb); 278 extern void * dst_alloc(struct dst_ops * ops); 279 extern void __dst_free(struct dst_entry * dst); 280 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 281 282 static inline void dst_free(struct dst_entry * dst) 283 { 284 if (dst->obsolete > 1) 285 return; 286 if (!atomic_read(&dst->__refcnt)) { 287 dst = dst_destroy(dst); 288 if (!dst) 289 return; 290 } 291 __dst_free(dst); 292 } 293 294 static inline void dst_rcu_free(struct rcu_head *head) 295 { 296 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 297 dst_free(dst); 298 } 299 300 static inline void dst_confirm(struct dst_entry *dst) 301 { 302 if (dst) 303 neigh_confirm(dst->neighbour); 304 } 305 306 static inline void dst_link_failure(struct sk_buff *skb) 307 { 308 struct dst_entry *dst = skb_dst(skb); 309 if (dst && dst->ops && dst->ops->link_failure) 310 dst->ops->link_failure(skb); 311 } 312 313 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 314 { 315 unsigned long expires = jiffies + timeout; 316 317 if (expires == 0) 318 expires = 1; 319 320 if (dst->expires == 0 || time_before(expires, dst->expires)) 321 dst->expires = expires; 322 } 323 324 /* Output packet to network from transport. */ 325 static inline int dst_output(struct sk_buff *skb) 326 { 327 return skb_dst(skb)->output(skb); 328 } 329 330 /* Input packet from network to transport. */ 331 static inline int dst_input(struct sk_buff *skb) 332 { 333 return skb_dst(skb)->input(skb); 334 } 335 336 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 337 { 338 if (dst->obsolete) 339 dst = dst->ops->check(dst, cookie); 340 return dst; 341 } 342 343 extern void dst_init(void); 344 345 /* Flags for xfrm_lookup flags argument. */ 346 enum { 347 XFRM_LOOKUP_WAIT = 1 << 0, 348 XFRM_LOOKUP_ICMP = 1 << 1, 349 }; 350 351 struct flowi; 352 #ifndef CONFIG_XFRM 353 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 354 struct flowi *fl, struct sock *sk, int flags) 355 { 356 return 0; 357 } 358 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 359 struct flowi *fl, struct sock *sk, int flags) 360 { 361 return 0; 362 } 363 #else 364 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 365 struct flowi *fl, struct sock *sk, int flags); 366 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 367 struct flowi *fl, struct sock *sk, int flags); 368 #endif 369 #endif 370 371 #endif /* _NET_DST_H */ 372