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 #define DST_GC_MIN (HZ/10) 20 #define DST_GC_INC (HZ/2) 21 #define DST_GC_MAX (120*HZ) 22 23 /* Each dst_entry has reference count and sits in some parent list(s). 24 * When it is removed from parent list, it is "freed" (dst_free). 25 * After this it enters dead state (dst->obsolete > 0) and if its refcnt 26 * is zero, it can be destroyed immediately, otherwise it is added 27 * to gc list and garbage collector periodically checks the refcnt. 28 */ 29 30 struct sk_buff; 31 32 struct dst_entry { 33 struct rcu_head rcu_head; 34 struct dst_entry *child; 35 struct net_device *dev; 36 struct dst_ops *ops; 37 unsigned long _metrics; 38 unsigned long expires; 39 struct dst_entry *path; 40 struct neighbour __rcu *_neighbour; 41 #ifdef CONFIG_XFRM 42 struct xfrm_state *xfrm; 43 #else 44 void *__pad1; 45 #endif 46 int (*input)(struct sk_buff*); 47 int (*output)(struct sk_buff*); 48 49 int flags; 50 #define DST_HOST 0x0001 51 #define DST_NOXFRM 0x0002 52 #define DST_NOPOLICY 0x0004 53 #define DST_NOHASH 0x0008 54 #define DST_NOCACHE 0x0010 55 #define DST_NOCOUNT 0x0020 56 57 short error; 58 short obsolete; 59 unsigned short header_len; /* more space at head required */ 60 unsigned short trailer_len; /* space to reserve at tail */ 61 #ifdef CONFIG_IP_ROUTE_CLASSID 62 __u32 tclassid; 63 #else 64 __u32 __pad2; 65 #endif 66 67 /* 68 * Align __refcnt to a 64 bytes alignment 69 * (L1_CACHE_SIZE would be too much) 70 */ 71 #ifdef CONFIG_64BIT 72 long __pad_to_align_refcnt[2]; 73 #endif 74 /* 75 * __refcnt wants to be on a different cache line from 76 * input/output/ops or performance tanks badly 77 */ 78 atomic_t __refcnt; /* client references */ 79 int __use; 80 unsigned long lastuse; 81 union { 82 struct dst_entry *next; 83 struct rtable __rcu *rt_next; 84 struct rt6_info *rt6_next; 85 struct dn_route __rcu *dn_next; 86 }; 87 }; 88 89 static inline struct neighbour *dst_get_neighbour(struct dst_entry *dst) 90 { 91 return rcu_dereference(dst->_neighbour); 92 } 93 94 static inline struct neighbour *dst_get_neighbour_raw(struct dst_entry *dst) 95 { 96 return rcu_dereference_raw(dst->_neighbour); 97 } 98 99 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh) 100 { 101 rcu_assign_pointer(dst->_neighbour, neigh); 102 } 103 104 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old); 105 extern const u32 dst_default_metrics[RTAX_MAX]; 106 107 #define DST_METRICS_READ_ONLY 0x1UL 108 #define __DST_METRICS_PTR(Y) \ 109 ((u32 *)((Y) & ~DST_METRICS_READ_ONLY)) 110 #define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics) 111 112 static inline bool dst_metrics_read_only(const struct dst_entry *dst) 113 { 114 return dst->_metrics & DST_METRICS_READ_ONLY; 115 } 116 117 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old); 118 119 static inline void dst_destroy_metrics_generic(struct dst_entry *dst) 120 { 121 unsigned long val = dst->_metrics; 122 if (!(val & DST_METRICS_READ_ONLY)) 123 __dst_destroy_metrics_generic(dst, val); 124 } 125 126 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst) 127 { 128 unsigned long p = dst->_metrics; 129 130 BUG_ON(!p); 131 132 if (p & DST_METRICS_READ_ONLY) 133 return dst->ops->cow_metrics(dst, p); 134 return __DST_METRICS_PTR(p); 135 } 136 137 /* This may only be invoked before the entry has reached global 138 * visibility. 139 */ 140 static inline void dst_init_metrics(struct dst_entry *dst, 141 const u32 *src_metrics, 142 bool read_only) 143 { 144 dst->_metrics = ((unsigned long) src_metrics) | 145 (read_only ? DST_METRICS_READ_ONLY : 0); 146 } 147 148 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src) 149 { 150 u32 *dst_metrics = dst_metrics_write_ptr(dest); 151 152 if (dst_metrics) { 153 u32 *src_metrics = DST_METRICS_PTR(src); 154 155 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32)); 156 } 157 } 158 159 static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 160 { 161 return DST_METRICS_PTR(dst); 162 } 163 164 static inline u32 165 dst_metric_raw(const struct dst_entry *dst, const int metric) 166 { 167 u32 *p = DST_METRICS_PTR(dst); 168 169 return p[metric-1]; 170 } 171 172 static inline u32 173 dst_metric(const struct dst_entry *dst, const int metric) 174 { 175 WARN_ON_ONCE(metric == RTAX_HOPLIMIT || 176 metric == RTAX_ADVMSS || 177 metric == RTAX_MTU); 178 return dst_metric_raw(dst, metric); 179 } 180 181 static inline u32 182 dst_metric_advmss(const struct dst_entry *dst) 183 { 184 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); 185 186 if (!advmss) 187 advmss = dst->ops->default_advmss(dst); 188 189 return advmss; 190 } 191 192 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) 193 { 194 u32 *p = dst_metrics_write_ptr(dst); 195 196 if (p) 197 p[metric-1] = val; 198 } 199 200 static inline u32 201 dst_feature(const struct dst_entry *dst, u32 feature) 202 { 203 return dst_metric(dst, RTAX_FEATURES) & feature; 204 } 205 206 static inline u32 dst_mtu(const struct dst_entry *dst) 207 { 208 u32 mtu = dst_metric_raw(dst, RTAX_MTU); 209 210 if (!mtu) 211 mtu = dst->ops->default_mtu(dst); 212 213 return mtu; 214 } 215 216 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 217 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 218 { 219 return msecs_to_jiffies(dst_metric(dst, metric)); 220 } 221 222 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric, 223 unsigned long rtt) 224 { 225 dst_metric_set(dst, metric, jiffies_to_msecs(rtt)); 226 } 227 228 static inline u32 229 dst_allfrag(const struct dst_entry *dst) 230 { 231 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 232 return ret; 233 } 234 235 static inline int 236 dst_metric_locked(const struct dst_entry *dst, int metric) 237 { 238 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 239 } 240 241 static inline void dst_hold(struct dst_entry * dst) 242 { 243 /* 244 * If your kernel compilation stops here, please check 245 * __pad_to_align_refcnt declaration in struct dst_entry 246 */ 247 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 248 atomic_inc(&dst->__refcnt); 249 } 250 251 static inline void dst_use(struct dst_entry *dst, unsigned long time) 252 { 253 dst_hold(dst); 254 dst->__use++; 255 dst->lastuse = time; 256 } 257 258 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 259 { 260 dst->__use++; 261 dst->lastuse = time; 262 } 263 264 static inline 265 struct dst_entry * dst_clone(struct dst_entry * dst) 266 { 267 if (dst) 268 atomic_inc(&dst->__refcnt); 269 return dst; 270 } 271 272 extern void dst_release(struct dst_entry *dst); 273 274 static inline void refdst_drop(unsigned long refdst) 275 { 276 if (!(refdst & SKB_DST_NOREF)) 277 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 278 } 279 280 /** 281 * skb_dst_drop - drops skb dst 282 * @skb: buffer 283 * 284 * Drops dst reference count if a reference was taken. 285 */ 286 static inline void skb_dst_drop(struct sk_buff *skb) 287 { 288 if (skb->_skb_refdst) { 289 refdst_drop(skb->_skb_refdst); 290 skb->_skb_refdst = 0UL; 291 } 292 } 293 294 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 295 { 296 nskb->_skb_refdst = oskb->_skb_refdst; 297 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 298 dst_clone(skb_dst(nskb)); 299 } 300 301 /** 302 * skb_dst_force - makes sure skb dst is refcounted 303 * @skb: buffer 304 * 305 * If dst is not yet refcounted, let's do it 306 */ 307 static inline void skb_dst_force(struct sk_buff *skb) 308 { 309 if (skb_dst_is_noref(skb)) { 310 WARN_ON(!rcu_read_lock_held()); 311 skb->_skb_refdst &= ~SKB_DST_NOREF; 312 dst_clone(skb_dst(skb)); 313 } 314 } 315 316 317 /** 318 * __skb_tunnel_rx - prepare skb for rx reinsert 319 * @skb: buffer 320 * @dev: tunnel device 321 * 322 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 323 * so make some cleanups. (no accounting done) 324 */ 325 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 326 { 327 skb->dev = dev; 328 329 /* 330 * Clear rxhash so that we can recalulate the hash for the 331 * encapsulated packet, unless we have already determine the hash 332 * over the L4 4-tuple. 333 */ 334 if (!skb->l4_rxhash) 335 skb->rxhash = 0; 336 skb_set_queue_mapping(skb, 0); 337 skb_dst_drop(skb); 338 nf_reset(skb); 339 } 340 341 /** 342 * skb_tunnel_rx - prepare skb for rx reinsert 343 * @skb: buffer 344 * @dev: tunnel device 345 * 346 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 347 * so make some cleanups, and perform accounting. 348 * Note: this accounting is not SMP safe. 349 */ 350 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 351 { 352 /* TODO : stats should be SMP safe */ 353 dev->stats.rx_packets++; 354 dev->stats.rx_bytes += skb->len; 355 __skb_tunnel_rx(skb, dev); 356 } 357 358 /* Children define the path of the packet through the 359 * Linux networking. Thus, destinations are stackable. 360 */ 361 362 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb) 363 { 364 struct dst_entry *child = dst_clone(skb_dst(skb)->child); 365 366 skb_dst_drop(skb); 367 return child; 368 } 369 370 extern int dst_discard(struct sk_buff *skb); 371 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev, 372 int initial_ref, int initial_obsolete, int flags); 373 extern void __dst_free(struct dst_entry * dst); 374 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 375 376 static inline void dst_free(struct dst_entry * dst) 377 { 378 if (dst->obsolete > 1) 379 return; 380 if (!atomic_read(&dst->__refcnt)) { 381 dst = dst_destroy(dst); 382 if (!dst) 383 return; 384 } 385 __dst_free(dst); 386 } 387 388 static inline void dst_rcu_free(struct rcu_head *head) 389 { 390 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 391 dst_free(dst); 392 } 393 394 static inline void dst_confirm(struct dst_entry *dst) 395 { 396 if (dst) { 397 struct neighbour *n; 398 399 rcu_read_lock(); 400 n = dst_get_neighbour(dst); 401 neigh_confirm(n); 402 rcu_read_unlock(); 403 } 404 } 405 406 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 407 { 408 return dst->ops->neigh_lookup(dst, daddr); 409 } 410 411 static inline void dst_link_failure(struct sk_buff *skb) 412 { 413 struct dst_entry *dst = skb_dst(skb); 414 if (dst && dst->ops && dst->ops->link_failure) 415 dst->ops->link_failure(skb); 416 } 417 418 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 419 { 420 unsigned long expires = jiffies + timeout; 421 422 if (expires == 0) 423 expires = 1; 424 425 if (dst->expires == 0 || time_before(expires, dst->expires)) 426 dst->expires = expires; 427 } 428 429 /* Output packet to network from transport. */ 430 static inline int dst_output(struct sk_buff *skb) 431 { 432 return skb_dst(skb)->output(skb); 433 } 434 435 /* Input packet from network to transport. */ 436 static inline int dst_input(struct sk_buff *skb) 437 { 438 return skb_dst(skb)->input(skb); 439 } 440 441 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 442 { 443 if (dst->obsolete) 444 dst = dst->ops->check(dst, cookie); 445 return dst; 446 } 447 448 extern void dst_init(void); 449 450 /* Flags for xfrm_lookup flags argument. */ 451 enum { 452 XFRM_LOOKUP_ICMP = 1 << 0, 453 }; 454 455 struct flowi; 456 #ifndef CONFIG_XFRM 457 static inline struct dst_entry *xfrm_lookup(struct net *net, 458 struct dst_entry *dst_orig, 459 const struct flowi *fl, struct sock *sk, 460 int flags) 461 { 462 return dst_orig; 463 } 464 #else 465 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 466 const struct flowi *fl, struct sock *sk, 467 int flags); 468 #endif 469 470 #endif /* _NET_DST_H */ 471