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