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 __rcu *rt_next; 99 struct rt6_info *rt6_next; 100 struct dn_route __rcu *dn_next; 101 }; 102 }; 103 104 #ifdef __KERNEL__ 105 106 static inline u32 107 dst_metric_raw(const struct dst_entry *dst, const int metric) 108 { 109 return dst->_metrics[metric-1]; 110 } 111 112 static inline u32 113 dst_metric(const struct dst_entry *dst, const int metric) 114 { 115 WARN_ON_ONCE(metric == RTAX_HOPLIMIT || 116 metric == RTAX_ADVMSS || 117 metric == RTAX_MTU); 118 return dst_metric_raw(dst, metric); 119 } 120 121 static inline u32 122 dst_metric_advmss(const struct dst_entry *dst) 123 { 124 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); 125 126 if (!advmss) 127 advmss = dst->ops->default_advmss(dst); 128 129 return advmss; 130 } 131 132 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) 133 { 134 dst->_metrics[metric-1] = val; 135 } 136 137 static inline void dst_import_metrics(struct dst_entry *dst, const u32 *src_metrics) 138 { 139 memcpy(dst->_metrics, src_metrics, RTAX_MAX * sizeof(u32)); 140 } 141 142 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src) 143 { 144 dst_import_metrics(dest, src->_metrics); 145 } 146 147 static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 148 { 149 return dst->_metrics; 150 } 151 152 static inline u32 153 dst_feature(const struct dst_entry *dst, u32 feature) 154 { 155 return dst_metric(dst, RTAX_FEATURES) & feature; 156 } 157 158 static inline u32 dst_mtu(const struct dst_entry *dst) 159 { 160 u32 mtu = dst_metric_raw(dst, RTAX_MTU); 161 162 if (!mtu) 163 mtu = dst->ops->default_mtu(dst); 164 165 return mtu; 166 } 167 168 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 169 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 170 { 171 return msecs_to_jiffies(dst_metric(dst, metric)); 172 } 173 174 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric, 175 unsigned long rtt) 176 { 177 dst_metric_set(dst, metric, jiffies_to_msecs(rtt)); 178 } 179 180 static inline u32 181 dst_allfrag(const struct dst_entry *dst) 182 { 183 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 184 /* Yes, _exactly_. This is paranoia. */ 185 barrier(); 186 return ret; 187 } 188 189 static inline int 190 dst_metric_locked(const struct dst_entry *dst, int metric) 191 { 192 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 193 } 194 195 static inline void dst_hold(struct dst_entry * dst) 196 { 197 /* 198 * If your kernel compilation stops here, please check 199 * __pad_to_align_refcnt declaration in struct dst_entry 200 */ 201 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 202 atomic_inc(&dst->__refcnt); 203 } 204 205 static inline void dst_use(struct dst_entry *dst, unsigned long time) 206 { 207 dst_hold(dst); 208 dst->__use++; 209 dst->lastuse = time; 210 } 211 212 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 213 { 214 dst->__use++; 215 dst->lastuse = time; 216 } 217 218 static inline 219 struct dst_entry * dst_clone(struct dst_entry * dst) 220 { 221 if (dst) 222 atomic_inc(&dst->__refcnt); 223 return dst; 224 } 225 226 extern void dst_release(struct dst_entry *dst); 227 228 static inline void refdst_drop(unsigned long refdst) 229 { 230 if (!(refdst & SKB_DST_NOREF)) 231 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 232 } 233 234 /** 235 * skb_dst_drop - drops skb dst 236 * @skb: buffer 237 * 238 * Drops dst reference count if a reference was taken. 239 */ 240 static inline void skb_dst_drop(struct sk_buff *skb) 241 { 242 if (skb->_skb_refdst) { 243 refdst_drop(skb->_skb_refdst); 244 skb->_skb_refdst = 0UL; 245 } 246 } 247 248 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 249 { 250 nskb->_skb_refdst = oskb->_skb_refdst; 251 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 252 dst_clone(skb_dst(nskb)); 253 } 254 255 /** 256 * skb_dst_force - makes sure skb dst is refcounted 257 * @skb: buffer 258 * 259 * If dst is not yet refcounted, let's do it 260 */ 261 static inline void skb_dst_force(struct sk_buff *skb) 262 { 263 if (skb_dst_is_noref(skb)) { 264 WARN_ON(!rcu_read_lock_held()); 265 skb->_skb_refdst &= ~SKB_DST_NOREF; 266 dst_clone(skb_dst(skb)); 267 } 268 } 269 270 271 /** 272 * __skb_tunnel_rx - prepare skb for rx reinsert 273 * @skb: buffer 274 * @dev: tunnel device 275 * 276 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 277 * so make some cleanups. (no accounting done) 278 */ 279 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 280 { 281 skb->dev = dev; 282 skb->rxhash = 0; 283 skb_set_queue_mapping(skb, 0); 284 skb_dst_drop(skb); 285 nf_reset(skb); 286 } 287 288 /** 289 * skb_tunnel_rx - prepare skb for rx reinsert 290 * @skb: buffer 291 * @dev: tunnel device 292 * 293 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 294 * so make some cleanups, and perform accounting. 295 * Note: this accounting is not SMP safe. 296 */ 297 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 298 { 299 /* TODO : stats should be SMP safe */ 300 dev->stats.rx_packets++; 301 dev->stats.rx_bytes += skb->len; 302 __skb_tunnel_rx(skb, dev); 303 } 304 305 /* Children define the path of the packet through the 306 * Linux networking. Thus, destinations are stackable. 307 */ 308 309 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb) 310 { 311 struct dst_entry *child = skb_dst(skb)->child; 312 313 skb_dst_drop(skb); 314 return child; 315 } 316 317 extern int dst_discard(struct sk_buff *skb); 318 extern void * dst_alloc(struct dst_ops * ops); 319 extern void __dst_free(struct dst_entry * dst); 320 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 321 322 static inline void dst_free(struct dst_entry * dst) 323 { 324 if (dst->obsolete > 1) 325 return; 326 if (!atomic_read(&dst->__refcnt)) { 327 dst = dst_destroy(dst); 328 if (!dst) 329 return; 330 } 331 __dst_free(dst); 332 } 333 334 static inline void dst_rcu_free(struct rcu_head *head) 335 { 336 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 337 dst_free(dst); 338 } 339 340 static inline void dst_confirm(struct dst_entry *dst) 341 { 342 if (dst) 343 neigh_confirm(dst->neighbour); 344 } 345 346 static inline void dst_link_failure(struct sk_buff *skb) 347 { 348 struct dst_entry *dst = skb_dst(skb); 349 if (dst && dst->ops && dst->ops->link_failure) 350 dst->ops->link_failure(skb); 351 } 352 353 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 354 { 355 unsigned long expires = jiffies + timeout; 356 357 if (expires == 0) 358 expires = 1; 359 360 if (dst->expires == 0 || time_before(expires, dst->expires)) 361 dst->expires = expires; 362 } 363 364 /* Output packet to network from transport. */ 365 static inline int dst_output(struct sk_buff *skb) 366 { 367 return skb_dst(skb)->output(skb); 368 } 369 370 /* Input packet from network to transport. */ 371 static inline int dst_input(struct sk_buff *skb) 372 { 373 return skb_dst(skb)->input(skb); 374 } 375 376 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 377 { 378 if (dst->obsolete) 379 dst = dst->ops->check(dst, cookie); 380 return dst; 381 } 382 383 extern void dst_init(void); 384 385 /* Flags for xfrm_lookup flags argument. */ 386 enum { 387 XFRM_LOOKUP_WAIT = 1 << 0, 388 XFRM_LOOKUP_ICMP = 1 << 1, 389 }; 390 391 struct flowi; 392 #ifndef CONFIG_XFRM 393 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 394 struct flowi *fl, struct sock *sk, int flags) 395 { 396 return 0; 397 } 398 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 399 struct flowi *fl, struct sock *sk, int flags) 400 { 401 return 0; 402 } 403 #else 404 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 405 struct flowi *fl, struct sock *sk, int flags); 406 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 407 struct flowi *fl, struct sock *sk, int flags); 408 #endif 409 #endif 410 411 #endif /* _NET_DST_H */ 412