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 { 41 struct rcu_head rcu_head; 42 struct dst_entry *child; 43 struct net_device *dev; 44 short error; 45 short obsolete; 46 int flags; 47 #define DST_HOST 1 48 #define DST_NOXFRM 2 49 #define DST_NOPOLICY 4 50 #define DST_NOHASH 8 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[2]; 88 #else 89 long __pad_to_align_refcnt[1]; 90 #endif 91 /* 92 * __refcnt wants to be on a different cache line from 93 * input/output/ops or performance tanks badly 94 */ 95 atomic_t __refcnt; /* client references */ 96 int __use; 97 unsigned long lastuse; 98 union { 99 struct dst_entry *next; 100 struct rtable *rt_next; 101 struct rt6_info *rt6_next; 102 struct dn_route *dn_next; 103 }; 104 }; 105 106 #ifdef __KERNEL__ 107 108 static inline u32 109 dst_metric(const struct dst_entry *dst, int metric) 110 { 111 return dst->metrics[metric-1]; 112 } 113 114 static inline u32 dst_mtu(const struct dst_entry *dst) 115 { 116 u32 mtu = dst_metric(dst, RTAX_MTU); 117 /* 118 * Alexey put it here, so ask him about it :) 119 */ 120 barrier(); 121 return mtu; 122 } 123 124 /* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */ 125 static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric) 126 { 127 return msecs_to_jiffies(dst_metric(dst, metric)); 128 } 129 130 static inline void set_dst_metric_rtt(struct dst_entry *dst, int metric, 131 unsigned long rtt) 132 { 133 dst->metrics[metric-1] = jiffies_to_msecs(rtt); 134 } 135 136 static inline u32 137 dst_allfrag(const struct dst_entry *dst) 138 { 139 int ret = dst_metric(dst, RTAX_FEATURES) & RTAX_FEATURE_ALLFRAG; 140 /* Yes, _exactly_. This is paranoia. */ 141 barrier(); 142 return ret; 143 } 144 145 static inline int 146 dst_metric_locked(struct dst_entry *dst, int metric) 147 { 148 return dst_metric(dst, RTAX_LOCK) & (1<<metric); 149 } 150 151 static inline void dst_hold(struct dst_entry * dst) 152 { 153 /* 154 * If your kernel compilation stops here, please check 155 * __pad_to_align_refcnt declaration in struct dst_entry 156 */ 157 BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63); 158 atomic_inc(&dst->__refcnt); 159 } 160 161 static inline void dst_use(struct dst_entry *dst, unsigned long time) 162 { 163 dst_hold(dst); 164 dst->__use++; 165 dst->lastuse = time; 166 } 167 168 static inline 169 struct dst_entry * dst_clone(struct dst_entry * dst) 170 { 171 if (dst) 172 atomic_inc(&dst->__refcnt); 173 return dst; 174 } 175 176 extern void dst_release(struct dst_entry *dst); 177 static inline void skb_dst_drop(struct sk_buff *skb) 178 { 179 if (skb->_skb_dst) 180 dst_release(skb_dst(skb)); 181 skb->_skb_dst = 0UL; 182 } 183 184 /* Children define the path of the packet through the 185 * Linux networking. Thus, destinations are stackable. 186 */ 187 188 static inline struct dst_entry *dst_pop(struct dst_entry *dst) 189 { 190 struct dst_entry *child = dst_clone(dst->child); 191 192 dst_release(dst); 193 return child; 194 } 195 196 extern int dst_discard(struct sk_buff *skb); 197 extern void * dst_alloc(struct dst_ops * ops); 198 extern void __dst_free(struct dst_entry * dst); 199 extern struct dst_entry *dst_destroy(struct dst_entry * dst); 200 201 static inline void dst_free(struct dst_entry * dst) 202 { 203 if (dst->obsolete > 1) 204 return; 205 if (!atomic_read(&dst->__refcnt)) { 206 dst = dst_destroy(dst); 207 if (!dst) 208 return; 209 } 210 __dst_free(dst); 211 } 212 213 static inline void dst_rcu_free(struct rcu_head *head) 214 { 215 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 216 dst_free(dst); 217 } 218 219 static inline void dst_confirm(struct dst_entry *dst) 220 { 221 if (dst) 222 neigh_confirm(dst->neighbour); 223 } 224 225 static inline void dst_negative_advice(struct dst_entry **dst_p) 226 { 227 struct dst_entry * dst = *dst_p; 228 if (dst && dst->ops->negative_advice) 229 *dst_p = dst->ops->negative_advice(dst); 230 } 231 232 static inline void dst_link_failure(struct sk_buff *skb) 233 { 234 struct dst_entry *dst = skb_dst(skb); 235 if (dst && dst->ops && dst->ops->link_failure) 236 dst->ops->link_failure(skb); 237 } 238 239 static inline void dst_set_expires(struct dst_entry *dst, int timeout) 240 { 241 unsigned long expires = jiffies + timeout; 242 243 if (expires == 0) 244 expires = 1; 245 246 if (dst->expires == 0 || time_before(expires, dst->expires)) 247 dst->expires = expires; 248 } 249 250 /* Output packet to network from transport. */ 251 static inline int dst_output(struct sk_buff *skb) 252 { 253 return skb_dst(skb)->output(skb); 254 } 255 256 /* Input packet from network to transport. */ 257 static inline int dst_input(struct sk_buff *skb) 258 { 259 return skb_dst(skb)->input(skb); 260 } 261 262 static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) 263 { 264 if (dst->obsolete) 265 dst = dst->ops->check(dst, cookie); 266 return dst; 267 } 268 269 extern void dst_init(void); 270 271 /* Flags for xfrm_lookup flags argument. */ 272 enum { 273 XFRM_LOOKUP_WAIT = 1 << 0, 274 XFRM_LOOKUP_ICMP = 1 << 1, 275 }; 276 277 struct flowi; 278 #ifndef CONFIG_XFRM 279 static inline int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 280 struct flowi *fl, struct sock *sk, int flags) 281 { 282 return 0; 283 } 284 static inline int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 285 struct flowi *fl, struct sock *sk, int flags) 286 { 287 return 0; 288 } 289 #else 290 extern int xfrm_lookup(struct net *net, struct dst_entry **dst_p, 291 struct flowi *fl, struct sock *sk, int flags); 292 extern int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, 293 struct flowi *fl, struct sock *sk, int flags); 294 #endif 295 #endif 296 297 #endif /* _NET_DST_H */ 298