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