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/bug.h> 16 #include <linux/jiffies.h> 17 #include <net/neighbour.h> 18 #include <asm/processor.h> 19 20 #define DST_GC_MIN (HZ/10) 21 #define DST_GC_INC (HZ/2) 22 #define DST_GC_MAX (120*HZ) 23 24 /* Each dst_entry has reference count and sits in some parent list(s). 25 * When it is removed from parent list, it is "freed" (dst_free). 26 * After this it enters dead state (dst->obsolete > 0) and if its refcnt 27 * is zero, it can be destroyed immediately, otherwise it is added 28 * to gc list and garbage collector periodically checks the refcnt. 29 */ 30 31 struct sk_buff; 32 33 struct dst_entry { 34 struct rcu_head rcu_head; 35 struct dst_entry *child; 36 struct net_device *dev; 37 struct dst_ops *ops; 38 unsigned long _metrics; 39 union { 40 unsigned long expires; 41 /* point to where the dst_entry copied from */ 42 struct dst_entry *from; 43 }; 44 struct dst_entry *path; 45 struct neighbour __rcu *_neighbour; 46 #ifdef CONFIG_XFRM 47 struct xfrm_state *xfrm; 48 #else 49 void *__pad1; 50 #endif 51 int (*input)(struct sk_buff*); 52 int (*output)(struct sk_buff*); 53 54 int flags; 55 #define DST_HOST 0x0001 56 #define DST_NOXFRM 0x0002 57 #define DST_NOPOLICY 0x0004 58 #define DST_NOHASH 0x0008 59 #define DST_NOCACHE 0x0010 60 #define DST_NOCOUNT 0x0020 61 #define DST_NOPEER 0x0040 62 #define DST_FAKE_RTABLE 0x0080 63 #define DST_XFRM_TUNNEL 0x0100 64 65 short error; 66 short obsolete; 67 unsigned short header_len; /* more space at head required */ 68 unsigned short trailer_len; /* space to reserve at tail */ 69 #ifdef CONFIG_IP_ROUTE_CLASSID 70 __u32 tclassid; 71 #else 72 __u32 __pad2; 73 #endif 74 75 /* 76 * Align __refcnt to a 64 bytes alignment 77 * (L1_CACHE_SIZE would be too much) 78 */ 79 #ifdef CONFIG_64BIT 80 long __pad_to_align_refcnt[2]; 81 #endif 82 /* 83 * __refcnt wants to be on a different cache line from 84 * input/output/ops or performance tanks badly 85 */ 86 atomic_t __refcnt; /* client references */ 87 int __use; 88 unsigned long lastuse; 89 union { 90 struct dst_entry *next; 91 struct rtable __rcu *rt_next; 92 struct rt6_info *rt6_next; 93 struct dn_route __rcu *dn_next; 94 }; 95 }; 96 97 static inline struct neighbour *dst_get_neighbour_noref(struct dst_entry *dst) 98 { 99 return rcu_dereference(dst->_neighbour); 100 } 101 102 static inline struct neighbour *dst_get_neighbour_noref_raw(struct dst_entry *dst) 103 { 104 return rcu_dereference_raw(dst->_neighbour); 105 } 106 107 static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh) 108 { 109 rcu_assign_pointer(dst->_neighbour, neigh); 110 } 111 112 extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old); 113 extern const u32 dst_default_metrics[RTAX_MAX]; 114 115 #define DST_METRICS_READ_ONLY 0x1UL 116 #define __DST_METRICS_PTR(Y) \ 117 ((u32 *)((Y) & ~DST_METRICS_READ_ONLY)) 118 #define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics) 119 120 static inline bool dst_metrics_read_only(const struct dst_entry *dst) 121 { 122 return dst->_metrics & DST_METRICS_READ_ONLY; 123 } 124 125 extern void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old); 126 127 static inline void dst_destroy_metrics_generic(struct dst_entry *dst) 128 { 129 unsigned long val = dst->_metrics; 130 if (!(val & DST_METRICS_READ_ONLY)) 131 __dst_destroy_metrics_generic(dst, val); 132 } 133 134 static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst) 135 { 136 unsigned long p = dst->_metrics; 137 138 BUG_ON(!p); 139 140 if (p & DST_METRICS_READ_ONLY) 141 return dst->ops->cow_metrics(dst, p); 142 return __DST_METRICS_PTR(p); 143 } 144 145 /* This may only be invoked before the entry has reached global 146 * visibility. 147 */ 148 static inline void dst_init_metrics(struct dst_entry *dst, 149 const u32 *src_metrics, 150 bool read_only) 151 { 152 dst->_metrics = ((unsigned long) src_metrics) | 153 (read_only ? DST_METRICS_READ_ONLY : 0); 154 } 155 156 static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src) 157 { 158 u32 *dst_metrics = dst_metrics_write_ptr(dest); 159 160 if (dst_metrics) { 161 u32 *src_metrics = DST_METRICS_PTR(src); 162 163 memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32)); 164 } 165 } 166 167 static inline u32 *dst_metrics_ptr(struct dst_entry *dst) 168 { 169 return DST_METRICS_PTR(dst); 170 } 171 172 static inline u32 173 dst_metric_raw(const struct dst_entry *dst, const int metric) 174 { 175 u32 *p = DST_METRICS_PTR(dst); 176 177 return p[metric-1]; 178 } 179 180 static inline u32 181 dst_metric(const struct dst_entry *dst, const int metric) 182 { 183 WARN_ON_ONCE(metric == RTAX_HOPLIMIT || 184 metric == RTAX_ADVMSS || 185 metric == RTAX_MTU); 186 return dst_metric_raw(dst, metric); 187 } 188 189 static inline u32 190 dst_metric_advmss(const struct dst_entry *dst) 191 { 192 u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS); 193 194 if (!advmss) 195 advmss = dst->ops->default_advmss(dst); 196 197 return advmss; 198 } 199 200 static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val) 201 { 202 u32 *p = dst_metrics_write_ptr(dst); 203 204 if (p) 205 p[metric-1] = val; 206 } 207 208 static inline u32 209 dst_feature(const struct dst_entry *dst, u32 feature) 210 { 211 return dst_metric(dst, RTAX_FEATURES) & feature; 212 } 213 214 static inline u32 dst_mtu(const struct dst_entry *dst) 215 { 216 return dst->ops->mtu(dst); 217 } 218 219 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 220 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 221 { 222 return msecs_to_jiffies(dst_metric(dst, metric)); 223 } 224 225 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric, 226 unsigned long rtt) 227 { 228 dst_metric_set(dst, metric, jiffies_to_msecs(rtt)); 229 } 230 231 static inline u32 232 dst_allfrag(const struct dst_entry *dst) 233 { 234 int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG); 235 return ret; 236 } 237 238 static inline int 239 dst_metric_locked(const struct dst_entry *dst, int metric) 240 { 241 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 242 } 243 244 static inline void dst_hold(struct dst_entry * dst) 245 { 246 /* 247 * If your kernel compilation stops here, please check 248 * __pad_to_align_refcnt declaration in struct dst_entry 249 */ 250 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 251 atomic_inc(&dst->__refcnt); 252 } 253 254 static inline void dst_use(struct dst_entry *dst, unsigned long time) 255 { 256 dst_hold(dst); 257 dst->__use++; 258 dst->lastuse = time; 259 } 260 261 static inline void dst_use_noref(struct dst_entry *dst, unsigned long time) 262 { 263 dst->__use++; 264 dst->lastuse = time; 265 } 266 267 static inline 268 struct dst_entry * dst_clone(struct dst_entry * dst) 269 { 270 if (dst) 271 atomic_inc(&dst->__refcnt); 272 return dst; 273 } 274 275 extern void dst_release(struct dst_entry *dst); 276 277 static inline void refdst_drop(unsigned long refdst) 278 { 279 if (!(refdst & SKB_DST_NOREF)) 280 dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK)); 281 } 282 283 /** 284 * skb_dst_drop - drops skb dst 285 * @skb: buffer 286 * 287 * Drops dst reference count if a reference was taken. 288 */ 289 static inline void skb_dst_drop(struct sk_buff *skb) 290 { 291 if (skb->_skb_refdst) { 292 refdst_drop(skb->_skb_refdst); 293 skb->_skb_refdst = 0UL; 294 } 295 } 296 297 static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb) 298 { 299 nskb->_skb_refdst = oskb->_skb_refdst; 300 if (!(nskb->_skb_refdst & SKB_DST_NOREF)) 301 dst_clone(skb_dst(nskb)); 302 } 303 304 /** 305 * skb_dst_force - makes sure skb dst is refcounted 306 * @skb: buffer 307 * 308 * If dst is not yet refcounted, let's do it 309 */ 310 static inline void skb_dst_force(struct sk_buff *skb) 311 { 312 if (skb_dst_is_noref(skb)) { 313 WARN_ON(!rcu_read_lock_held()); 314 skb->_skb_refdst &= ~SKB_DST_NOREF; 315 dst_clone(skb_dst(skb)); 316 } 317 } 318 319 320 /** 321 * __skb_tunnel_rx - prepare skb for rx reinsert 322 * @skb: buffer 323 * @dev: tunnel device 324 * 325 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 326 * so make some cleanups. (no accounting done) 327 */ 328 static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 329 { 330 skb->dev = dev; 331 332 /* 333 * Clear rxhash so that we can recalulate the hash for the 334 * encapsulated packet, unless we have already determine the hash 335 * over the L4 4-tuple. 336 */ 337 if (!skb->l4_rxhash) 338 skb->rxhash = 0; 339 skb_set_queue_mapping(skb, 0); 340 skb_dst_drop(skb); 341 nf_reset(skb); 342 } 343 344 /** 345 * skb_tunnel_rx - prepare skb for rx reinsert 346 * @skb: buffer 347 * @dev: tunnel device 348 * 349 * After decapsulation, packet is going to re-enter (netif_rx()) our stack, 350 * so make some cleanups, and perform accounting. 351 * Note: this accounting is not SMP safe. 352 */ 353 static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev) 354 { 355 /* TODO : stats should be SMP safe */ 356 dev->stats.rx_packets++; 357 dev->stats.rx_bytes += skb->len; 358 __skb_tunnel_rx(skb, dev); 359 } 360 361 /* Children define the path of the packet through the 362 * Linux networking. Thus, destinations are stackable. 363 */ 364 365 static inline struct dst_entry *skb_dst_pop(struct sk_buff *skb) 366 { 367 struct dst_entry *child = dst_clone(skb_dst(skb)->child); 368 369 skb_dst_drop(skb); 370 return child; 371 } 372 373 extern int dst_discard(struct sk_buff *skb); 374 extern void *dst_alloc(struct dst_ops * ops, struct net_device *dev, 375 int initial_ref, int initial_obsolete, int flags); 376 extern void __dst_free(struct dst_entry * dst); 377 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 378 379 static inline void dst_free(struct dst_entry * dst) 380 { 381 if (dst->obsolete > 1) 382 return; 383 if (!atomic_read(&dst->__refcnt)) { 384 dst = dst_destroy(dst); 385 if (!dst) 386 return; 387 } 388 __dst_free(dst); 389 } 390 391 static inline void dst_rcu_free(struct rcu_head *head) 392 { 393 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 394 dst_free(dst); 395 } 396 397 static inline void dst_confirm(struct dst_entry *dst) 398 { 399 if (dst) { 400 struct neighbour *n; 401 402 rcu_read_lock(); 403 n = dst_get_neighbour_noref(dst); 404 neigh_confirm(n); 405 rcu_read_unlock(); 406 } 407 } 408 409 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr) 410 { 411 return dst->ops->neigh_lookup(dst, daddr); 412 } 413 414 static inline void dst_link_failure(struct sk_buff *skb) 415 { 416 struct dst_entry *dst = skb_dst(skb); 417 if (dst && dst->ops && dst->ops->link_failure) 418 dst->ops->link_failure(skb); 419 } 420 421 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 422 { 423 unsigned long expires = jiffies + timeout; 424 425 if (expires == 0) 426 expires = 1; 427 428 if (dst->expires == 0 || time_before(expires, dst->expires)) 429 dst->expires = expires; 430 } 431 432 /* Output packet to network from transport. */ 433 static inline int dst_output(struct sk_buff *skb) 434 { 435 return skb_dst(skb)->output(skb); 436 } 437 438 /* Input packet from network to transport. */ 439 static inline int dst_input(struct sk_buff *skb) 440 { 441 return skb_dst(skb)->input(skb); 442 } 443 444 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 445 { 446 if (dst->obsolete) 447 dst = dst->ops->check(dst, cookie); 448 return dst; 449 } 450 451 extern void dst_init(void); 452 453 /* Flags for xfrm_lookup flags argument. */ 454 enum { 455 XFRM_LOOKUP_ICMP = 1 << 0, 456 }; 457 458 struct flowi; 459 #ifndef CONFIG_XFRM 460 static inline struct dst_entry *xfrm_lookup(struct net *net, 461 struct dst_entry *dst_orig, 462 const struct flowi *fl, struct sock *sk, 463 int flags) 464 { 465 return dst_orig; 466 } 467 #else 468 extern struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig, 469 const struct flowi *fl, struct sock *sk, 470 int flags); 471 #endif 472 473 #endif /* _NET_DST_H */ 474