tcp: fix tcp_ack() performance problem
[pandora-kernel.git] / net / ipv4 / fib_semantics.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the  BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              IPv4 Forwarding Information Base: semantics.
7  *
8  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
9  *
10  *              This program is free software; you can redistribute it and/or
11  *              modify it under the terms of the GNU General Public License
12  *              as published by the Free Software Foundation; either version
13  *              2 of the License, or (at your option) any later version.
14  */
15
16 #include <asm/uaccess.h>
17 #include <linux/bitops.h>
18 #include <linux/types.h>
19 #include <linux/kernel.h>
20 #include <linux/jiffies.h>
21 #include <linux/mm.h>
22 #include <linux/string.h>
23 #include <linux/socket.h>
24 #include <linux/sockios.h>
25 #include <linux/errno.h>
26 #include <linux/in.h>
27 #include <linux/inet.h>
28 #include <linux/inetdevice.h>
29 #include <linux/netdevice.h>
30 #include <linux/if_arp.h>
31 #include <linux/proc_fs.h>
32 #include <linux/skbuff.h>
33 #include <linux/init.h>
34 #include <linux/slab.h>
35
36 #include <net/arp.h>
37 #include <net/ip.h>
38 #include <net/protocol.h>
39 #include <net/route.h>
40 #include <net/tcp.h>
41 #include <net/sock.h>
42 #include <net/ip_fib.h>
43 #include <net/netlink.h>
44 #include <net/nexthop.h>
45
46 #include "fib_lookup.h"
47
48 static DEFINE_SPINLOCK(fib_info_lock);
49 static struct hlist_head *fib_info_hash;
50 static struct hlist_head *fib_info_laddrhash;
51 static unsigned int fib_info_hash_size;
52 static unsigned int fib_info_cnt;
53
54 #define DEVINDEX_HASHBITS 8
55 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
56 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
57
58 #ifdef CONFIG_IP_ROUTE_MULTIPATH
59
60 static DEFINE_SPINLOCK(fib_multipath_lock);
61
62 #define for_nexthops(fi) {                                              \
63         int nhsel; const struct fib_nh *nh;                             \
64         for (nhsel = 0, nh = (fi)->fib_nh;                              \
65              nhsel < (fi)->fib_nhs;                                     \
66              nh++, nhsel++)
67
68 #define change_nexthops(fi) {                                           \
69         int nhsel; struct fib_nh *nexthop_nh;                           \
70         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
71              nhsel < (fi)->fib_nhs;                                     \
72              nexthop_nh++, nhsel++)
73
74 #else /* CONFIG_IP_ROUTE_MULTIPATH */
75
76 /* Hope, that gcc will optimize it to get rid of dummy loop */
77
78 #define for_nexthops(fi) {                                              \
79         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
80         for (nhsel = 0; nhsel < 1; nhsel++)
81
82 #define change_nexthops(fi) {                                           \
83         int nhsel;                                                      \
84         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
85         for (nhsel = 0; nhsel < 1; nhsel++)
86
87 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
88
89 #define endfor_nexthops(fi) }
90
91
92 const struct fib_prop fib_props[RTN_MAX + 1] = {
93         [RTN_UNSPEC] = {
94                 .error  = 0,
95                 .scope  = RT_SCOPE_NOWHERE,
96         },
97         [RTN_UNICAST] = {
98                 .error  = 0,
99                 .scope  = RT_SCOPE_UNIVERSE,
100         },
101         [RTN_LOCAL] = {
102                 .error  = 0,
103                 .scope  = RT_SCOPE_HOST,
104         },
105         [RTN_BROADCAST] = {
106                 .error  = 0,
107                 .scope  = RT_SCOPE_LINK,
108         },
109         [RTN_ANYCAST] = {
110                 .error  = 0,
111                 .scope  = RT_SCOPE_LINK,
112         },
113         [RTN_MULTICAST] = {
114                 .error  = 0,
115                 .scope  = RT_SCOPE_UNIVERSE,
116         },
117         [RTN_BLACKHOLE] = {
118                 .error  = -EINVAL,
119                 .scope  = RT_SCOPE_UNIVERSE,
120         },
121         [RTN_UNREACHABLE] = {
122                 .error  = -EHOSTUNREACH,
123                 .scope  = RT_SCOPE_UNIVERSE,
124         },
125         [RTN_PROHIBIT] = {
126                 .error  = -EACCES,
127                 .scope  = RT_SCOPE_UNIVERSE,
128         },
129         [RTN_THROW] = {
130                 .error  = -EAGAIN,
131                 .scope  = RT_SCOPE_UNIVERSE,
132         },
133         [RTN_NAT] = {
134                 .error  = -EINVAL,
135                 .scope  = RT_SCOPE_NOWHERE,
136         },
137         [RTN_XRESOLVE] = {
138                 .error  = -EINVAL,
139                 .scope  = RT_SCOPE_NOWHERE,
140         },
141 };
142
143 static void rt_fibinfo_free(struct rtable __rcu **rtp)
144 {
145         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
146
147         if (!rt)
148                 return;
149
150         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
151          * because we waited an RCU grace period before calling
152          * free_fib_info_rcu()
153          */
154
155         dst_free(&rt->dst);
156 }
157
158 static void free_nh_exceptions(struct fib_nh *nh)
159 {
160         struct fnhe_hash_bucket *hash;
161         int i;
162
163         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
164         if (!hash)
165                 return;
166         for (i = 0; i < FNHE_HASH_SIZE; i++) {
167                 struct fib_nh_exception *fnhe;
168
169                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
170                 while (fnhe) {
171                         struct fib_nh_exception *next;
172                         
173                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
174
175                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
176                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
177
178                         kfree(fnhe);
179
180                         fnhe = next;
181                 }
182         }
183         kfree(hash);
184 }
185
186 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
187 {
188         int cpu;
189
190         if (!rtp)
191                 return;
192
193         for_each_possible_cpu(cpu) {
194                 struct rtable *rt;
195
196                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
197                 if (rt)
198                         dst_free(&rt->dst);
199         }
200         free_percpu(rtp);
201 }
202
203 /* Release a nexthop info record */
204 static void free_fib_info_rcu(struct rcu_head *head)
205 {
206         struct fib_info *fi = container_of(head, struct fib_info, rcu);
207
208         change_nexthops(fi) {
209                 if (nexthop_nh->nh_dev)
210                         dev_put(nexthop_nh->nh_dev);
211                 free_nh_exceptions(nexthop_nh);
212                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
213                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
214         } endfor_nexthops(fi);
215
216         release_net(fi->fib_net);
217         if (fi->fib_metrics != (u32 *) dst_default_metrics)
218                 kfree(fi->fib_metrics);
219         kfree(fi);
220 }
221
222 void free_fib_info(struct fib_info *fi)
223 {
224         if (fi->fib_dead == 0) {
225                 pr_warn("Freeing alive fib_info %p\n", fi);
226                 return;
227         }
228         fib_info_cnt--;
229 #ifdef CONFIG_IP_ROUTE_CLASSID
230         change_nexthops(fi) {
231                 if (nexthop_nh->nh_tclassid)
232                         fi->fib_net->ipv4.fib_num_tclassid_users--;
233         } endfor_nexthops(fi);
234 #endif
235         call_rcu(&fi->rcu, free_fib_info_rcu);
236 }
237
238 void fib_release_info(struct fib_info *fi)
239 {
240         spin_lock_bh(&fib_info_lock);
241         if (fi && --fi->fib_treeref == 0) {
242                 hlist_del(&fi->fib_hash);
243                 if (fi->fib_prefsrc)
244                         hlist_del(&fi->fib_lhash);
245                 change_nexthops(fi) {
246                         if (!nexthop_nh->nh_dev)
247                                 continue;
248                         hlist_del(&nexthop_nh->nh_hash);
249                 } endfor_nexthops(fi)
250                 fi->fib_dead = 1;
251                 fib_info_put(fi);
252         }
253         spin_unlock_bh(&fib_info_lock);
254 }
255
256 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
257 {
258         const struct fib_nh *onh = ofi->fib_nh;
259
260         for_nexthops(fi) {
261                 if (nh->nh_oif != onh->nh_oif ||
262                     nh->nh_gw  != onh->nh_gw ||
263                     nh->nh_scope != onh->nh_scope ||
264 #ifdef CONFIG_IP_ROUTE_MULTIPATH
265                     nh->nh_weight != onh->nh_weight ||
266 #endif
267 #ifdef CONFIG_IP_ROUTE_CLASSID
268                     nh->nh_tclassid != onh->nh_tclassid ||
269 #endif
270                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_F_DEAD))
271                         return -1;
272                 onh++;
273         } endfor_nexthops(fi);
274         return 0;
275 }
276
277 static inline unsigned int fib_devindex_hashfn(unsigned int val)
278 {
279         unsigned int mask = DEVINDEX_HASHSIZE - 1;
280
281         return (val ^
282                 (val >> DEVINDEX_HASHBITS) ^
283                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
284 }
285
286 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
287 {
288         unsigned int mask = (fib_info_hash_size - 1);
289         unsigned int val = fi->fib_nhs;
290
291         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
292         val ^= (__force u32)fi->fib_prefsrc;
293         val ^= fi->fib_priority;
294         for_nexthops(fi) {
295                 val ^= fib_devindex_hashfn(nh->nh_oif);
296         } endfor_nexthops(fi)
297
298         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
299 }
300
301 static struct fib_info *fib_find_info(const struct fib_info *nfi)
302 {
303         struct hlist_head *head;
304         struct fib_info *fi;
305         unsigned int hash;
306
307         hash = fib_info_hashfn(nfi);
308         head = &fib_info_hash[hash];
309
310         hlist_for_each_entry(fi, head, fib_hash) {
311                 if (!net_eq(fi->fib_net, nfi->fib_net))
312                         continue;
313                 if (fi->fib_nhs != nfi->fib_nhs)
314                         continue;
315                 if (nfi->fib_protocol == fi->fib_protocol &&
316                     nfi->fib_scope == fi->fib_scope &&
317                     nfi->fib_prefsrc == fi->fib_prefsrc &&
318                     nfi->fib_priority == fi->fib_priority &&
319                     nfi->fib_type == fi->fib_type &&
320                     memcmp(nfi->fib_metrics, fi->fib_metrics,
321                            sizeof(u32) * RTAX_MAX) == 0 &&
322                     ((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_F_DEAD) == 0 &&
323                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
324                         return fi;
325         }
326
327         return NULL;
328 }
329
330 /* Check, that the gateway is already configured.
331  * Used only by redirect accept routine.
332  */
333 int ip_fib_check_default(__be32 gw, struct net_device *dev)
334 {
335         struct hlist_head *head;
336         struct fib_nh *nh;
337         unsigned int hash;
338
339         spin_lock(&fib_info_lock);
340
341         hash = fib_devindex_hashfn(dev->ifindex);
342         head = &fib_info_devhash[hash];
343         hlist_for_each_entry(nh, head, nh_hash) {
344                 if (nh->nh_dev == dev &&
345                     nh->nh_gw == gw &&
346                     !(nh->nh_flags & RTNH_F_DEAD)) {
347                         spin_unlock(&fib_info_lock);
348                         return 0;
349                 }
350         }
351
352         spin_unlock(&fib_info_lock);
353
354         return -1;
355 }
356
357 static inline size_t fib_nlmsg_size(struct fib_info *fi)
358 {
359         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
360                          + nla_total_size(4) /* RTA_TABLE */
361                          + nla_total_size(4) /* RTA_DST */
362                          + nla_total_size(4) /* RTA_PRIORITY */
363                          + nla_total_size(4); /* RTA_PREFSRC */
364
365         /* space for nested metrics */
366         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
367
368         if (fi->fib_nhs) {
369                 /* Also handles the special case fib_nhs == 1 */
370
371                 /* each nexthop is packed in an attribute */
372                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
373
374                 /* may contain flow and gateway attribute */
375                 nhsize += 2 * nla_total_size(4);
376
377                 /* all nexthops are packed in a nested attribute */
378                 payload += nla_total_size(fi->fib_nhs * nhsize);
379         }
380
381         return payload;
382 }
383
384 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
385                int dst_len, u32 tb_id, const struct nl_info *info,
386                unsigned int nlm_flags)
387 {
388         struct sk_buff *skb;
389         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
390         int err = -ENOBUFS;
391
392         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
393         if (skb == NULL)
394                 goto errout;
395
396         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
397                             fa->fa_type, key, dst_len,
398                             fa->fa_tos, fa->fa_info, nlm_flags);
399         if (err < 0) {
400                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
401                 WARN_ON(err == -EMSGSIZE);
402                 kfree_skb(skb);
403                 goto errout;
404         }
405         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
406                     info->nlh, GFP_KERNEL);
407         return;
408 errout:
409         if (err < 0)
410                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
411 }
412
413 /* Return the first fib alias matching TOS with
414  * priority less than or equal to PRIO.
415  */
416 struct fib_alias *fib_find_alias(struct list_head *fah, u8 tos, u32 prio)
417 {
418         if (fah) {
419                 struct fib_alias *fa;
420                 list_for_each_entry(fa, fah, fa_list) {
421                         if (fa->fa_tos > tos)
422                                 continue;
423                         if (fa->fa_info->fib_priority >= prio ||
424                             fa->fa_tos < tos)
425                                 return fa;
426                 }
427         }
428         return NULL;
429 }
430
431 static int fib_detect_death(struct fib_info *fi, int order,
432                             struct fib_info **last_resort, int *last_idx,
433                             int dflt)
434 {
435         struct neighbour *n;
436         int state = NUD_NONE;
437
438         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
439         if (n) {
440                 state = n->nud_state;
441                 neigh_release(n);
442         }
443         if (state == NUD_REACHABLE)
444                 return 0;
445         if ((state & NUD_VALID) && order != dflt)
446                 return 0;
447         if ((state & NUD_VALID) ||
448             (*last_idx < 0 && order > dflt)) {
449                 *last_resort = fi;
450                 *last_idx = order;
451         }
452         return 1;
453 }
454
455 #ifdef CONFIG_IP_ROUTE_MULTIPATH
456
457 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining)
458 {
459         int nhs = 0;
460
461         while (rtnh_ok(rtnh, remaining)) {
462                 nhs++;
463                 rtnh = rtnh_next(rtnh, &remaining);
464         }
465
466         /* leftover implies invalid nexthop configuration, discard it */
467         return remaining > 0 ? 0 : nhs;
468 }
469
470 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
471                        int remaining, struct fib_config *cfg)
472 {
473         change_nexthops(fi) {
474                 int attrlen;
475
476                 if (!rtnh_ok(rtnh, remaining))
477                         return -EINVAL;
478
479                 nexthop_nh->nh_flags =
480                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
481                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
482                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
483
484                 attrlen = rtnh_attrlen(rtnh);
485                 if (attrlen > 0) {
486                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
487
488                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
489                         nexthop_nh->nh_gw = nla ? nla_get_be32(nla) : 0;
490 #ifdef CONFIG_IP_ROUTE_CLASSID
491                         nla = nla_find(attrs, attrlen, RTA_FLOW);
492                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
493                         if (nexthop_nh->nh_tclassid)
494                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
495 #endif
496                 }
497
498                 rtnh = rtnh_next(rtnh, &remaining);
499         } endfor_nexthops(fi);
500
501         return 0;
502 }
503
504 #endif
505
506 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi)
507 {
508 #ifdef CONFIG_IP_ROUTE_MULTIPATH
509         struct rtnexthop *rtnh;
510         int remaining;
511 #endif
512
513         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
514                 return 1;
515
516         if (cfg->fc_oif || cfg->fc_gw) {
517                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
518                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
519                         return 0;
520                 return 1;
521         }
522
523 #ifdef CONFIG_IP_ROUTE_MULTIPATH
524         if (cfg->fc_mp == NULL)
525                 return 0;
526
527         rtnh = cfg->fc_mp;
528         remaining = cfg->fc_mp_len;
529
530         for_nexthops(fi) {
531                 int attrlen;
532
533                 if (!rtnh_ok(rtnh, remaining))
534                         return -EINVAL;
535
536                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
537                         return 1;
538
539                 attrlen = rtnh_attrlen(rtnh);
540                 if (attrlen < 0) {
541                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
542
543                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
544                         if (nla && nla_get_be32(nla) != nh->nh_gw)
545                                 return 1;
546 #ifdef CONFIG_IP_ROUTE_CLASSID
547                         nla = nla_find(attrs, attrlen, RTA_FLOW);
548                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
549                                 return 1;
550 #endif
551                 }
552
553                 rtnh = rtnh_next(rtnh, &remaining);
554         } endfor_nexthops(fi);
555 #endif
556         return 0;
557 }
558
559
560 /*
561  * Picture
562  * -------
563  *
564  * Semantics of nexthop is very messy by historical reasons.
565  * We have to take into account, that:
566  * a) gateway can be actually local interface address,
567  *    so that gatewayed route is direct.
568  * b) gateway must be on-link address, possibly
569  *    described not by an ifaddr, but also by a direct route.
570  * c) If both gateway and interface are specified, they should not
571  *    contradict.
572  * d) If we use tunnel routes, gateway could be not on-link.
573  *
574  * Attempt to reconcile all of these (alas, self-contradictory) conditions
575  * results in pretty ugly and hairy code with obscure logic.
576  *
577  * I chose to generalized it instead, so that the size
578  * of code does not increase practically, but it becomes
579  * much more general.
580  * Every prefix is assigned a "scope" value: "host" is local address,
581  * "link" is direct route,
582  * [ ... "site" ... "interior" ... ]
583  * and "universe" is true gateway route with global meaning.
584  *
585  * Every prefix refers to a set of "nexthop"s (gw, oif),
586  * where gw must have narrower scope. This recursion stops
587  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
588  * which means that gw is forced to be on link.
589  *
590  * Code is still hairy, but now it is apparently logically
591  * consistent and very flexible. F.e. as by-product it allows
592  * to co-exists in peace independent exterior and interior
593  * routing processes.
594  *
595  * Normally it looks as following.
596  *
597  * {universe prefix}  -> (gw, oif) [scope link]
598  *                |
599  *                |-> {link prefix} -> (gw, oif) [scope local]
600  *                                      |
601  *                                      |-> {local prefix} (terminal node)
602  */
603 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
604                         struct fib_nh *nh)
605 {
606         int err;
607         struct net *net;
608         struct net_device *dev;
609
610         net = cfg->fc_nlinfo.nl_net;
611         if (nh->nh_gw) {
612                 struct fib_result res;
613
614                 if (nh->nh_flags & RTNH_F_ONLINK) {
615
616                         if (cfg->fc_scope >= RT_SCOPE_LINK)
617                                 return -EINVAL;
618                         if (inet_addr_type(net, nh->nh_gw) != RTN_UNICAST)
619                                 return -EINVAL;
620                         dev = __dev_get_by_index(net, nh->nh_oif);
621                         if (!dev)
622                                 return -ENODEV;
623                         if (!(dev->flags & IFF_UP))
624                                 return -ENETDOWN;
625                         nh->nh_dev = dev;
626                         dev_hold(dev);
627                         nh->nh_scope = RT_SCOPE_LINK;
628                         return 0;
629                 }
630                 rcu_read_lock();
631                 {
632                         struct flowi4 fl4 = {
633                                 .daddr = nh->nh_gw,
634                                 .flowi4_scope = cfg->fc_scope + 1,
635                                 .flowi4_oif = nh->nh_oif,
636                                 .flowi4_iif = LOOPBACK_IFINDEX,
637                         };
638
639                         /* It is not necessary, but requires a bit of thinking */
640                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
641                                 fl4.flowi4_scope = RT_SCOPE_LINK;
642                         err = fib_lookup(net, &fl4, &res);
643                         if (err) {
644                                 rcu_read_unlock();
645                                 return err;
646                         }
647                 }
648                 err = -EINVAL;
649                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL)
650                         goto out;
651                 nh->nh_scope = res.scope;
652                 nh->nh_oif = FIB_RES_OIF(res);
653                 nh->nh_dev = dev = FIB_RES_DEV(res);
654                 if (!dev)
655                         goto out;
656                 dev_hold(dev);
657                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
658         } else {
659                 struct in_device *in_dev;
660
661                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK))
662                         return -EINVAL;
663
664                 rcu_read_lock();
665                 err = -ENODEV;
666                 in_dev = inetdev_by_index(net, nh->nh_oif);
667                 if (in_dev == NULL)
668                         goto out;
669                 err = -ENETDOWN;
670                 if (!(in_dev->dev->flags & IFF_UP))
671                         goto out;
672                 nh->nh_dev = in_dev->dev;
673                 dev_hold(nh->nh_dev);
674                 nh->nh_scope = RT_SCOPE_HOST;
675                 err = 0;
676         }
677 out:
678         rcu_read_unlock();
679         return err;
680 }
681
682 static inline unsigned int fib_laddr_hashfn(__be32 val)
683 {
684         unsigned int mask = (fib_info_hash_size - 1);
685
686         return ((__force u32)val ^
687                 ((__force u32)val >> 7) ^
688                 ((__force u32)val >> 14)) & mask;
689 }
690
691 static struct hlist_head *fib_info_hash_alloc(int bytes)
692 {
693         if (bytes <= PAGE_SIZE)
694                 return kzalloc(bytes, GFP_KERNEL);
695         else
696                 return (struct hlist_head *)
697                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
698                                          get_order(bytes));
699 }
700
701 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
702 {
703         if (!hash)
704                 return;
705
706         if (bytes <= PAGE_SIZE)
707                 kfree(hash);
708         else
709                 free_pages((unsigned long) hash, get_order(bytes));
710 }
711
712 static void fib_info_hash_move(struct hlist_head *new_info_hash,
713                                struct hlist_head *new_laddrhash,
714                                unsigned int new_size)
715 {
716         struct hlist_head *old_info_hash, *old_laddrhash;
717         unsigned int old_size = fib_info_hash_size;
718         unsigned int i, bytes;
719
720         spin_lock_bh(&fib_info_lock);
721         old_info_hash = fib_info_hash;
722         old_laddrhash = fib_info_laddrhash;
723         fib_info_hash_size = new_size;
724
725         for (i = 0; i < old_size; i++) {
726                 struct hlist_head *head = &fib_info_hash[i];
727                 struct hlist_node *n;
728                 struct fib_info *fi;
729
730                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
731                         struct hlist_head *dest;
732                         unsigned int new_hash;
733
734                         hlist_del(&fi->fib_hash);
735
736                         new_hash = fib_info_hashfn(fi);
737                         dest = &new_info_hash[new_hash];
738                         hlist_add_head(&fi->fib_hash, dest);
739                 }
740         }
741         fib_info_hash = new_info_hash;
742
743         for (i = 0; i < old_size; i++) {
744                 struct hlist_head *lhead = &fib_info_laddrhash[i];
745                 struct hlist_node *n;
746                 struct fib_info *fi;
747
748                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
749                         struct hlist_head *ldest;
750                         unsigned int new_hash;
751
752                         hlist_del(&fi->fib_lhash);
753
754                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
755                         ldest = &new_laddrhash[new_hash];
756                         hlist_add_head(&fi->fib_lhash, ldest);
757                 }
758         }
759         fib_info_laddrhash = new_laddrhash;
760
761         spin_unlock_bh(&fib_info_lock);
762
763         bytes = old_size * sizeof(struct hlist_head *);
764         fib_info_hash_free(old_info_hash, bytes);
765         fib_info_hash_free(old_laddrhash, bytes);
766 }
767
768 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
769 {
770         nh->nh_saddr = inet_select_addr(nh->nh_dev,
771                                         nh->nh_gw,
772                                         nh->nh_parent->fib_scope);
773         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
774
775         return nh->nh_saddr;
776 }
777
778 struct fib_info *fib_create_info(struct fib_config *cfg)
779 {
780         int err;
781         struct fib_info *fi = NULL;
782         struct fib_info *ofi;
783         int nhs = 1;
784         struct net *net = cfg->fc_nlinfo.nl_net;
785
786         if (cfg->fc_type > RTN_MAX)
787                 goto err_inval;
788
789         /* Fast check to catch the most weird cases */
790         if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
791                 goto err_inval;
792
793 #ifdef CONFIG_IP_ROUTE_MULTIPATH
794         if (cfg->fc_mp) {
795                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len);
796                 if (nhs == 0)
797                         goto err_inval;
798         }
799 #endif
800
801         err = -ENOBUFS;
802         if (fib_info_cnt >= fib_info_hash_size) {
803                 unsigned int new_size = fib_info_hash_size << 1;
804                 struct hlist_head *new_info_hash;
805                 struct hlist_head *new_laddrhash;
806                 unsigned int bytes;
807
808                 if (!new_size)
809                         new_size = 16;
810                 bytes = new_size * sizeof(struct hlist_head *);
811                 new_info_hash = fib_info_hash_alloc(bytes);
812                 new_laddrhash = fib_info_hash_alloc(bytes);
813                 if (!new_info_hash || !new_laddrhash) {
814                         fib_info_hash_free(new_info_hash, bytes);
815                         fib_info_hash_free(new_laddrhash, bytes);
816                 } else
817                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
818
819                 if (!fib_info_hash_size)
820                         goto failure;
821         }
822
823         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
824         if (fi == NULL)
825                 goto failure;
826         fib_info_cnt++;
827         if (cfg->fc_mx) {
828                 fi->fib_metrics = kzalloc(sizeof(u32) * RTAX_MAX, GFP_KERNEL);
829                 if (!fi->fib_metrics)
830                         goto failure;
831         } else
832                 fi->fib_metrics = (u32 *) dst_default_metrics;
833
834         fi->fib_net = hold_net(net);
835         fi->fib_protocol = cfg->fc_protocol;
836         fi->fib_scope = cfg->fc_scope;
837         fi->fib_flags = cfg->fc_flags;
838         fi->fib_priority = cfg->fc_priority;
839         fi->fib_prefsrc = cfg->fc_prefsrc;
840         fi->fib_type = cfg->fc_type;
841
842         fi->fib_nhs = nhs;
843         change_nexthops(fi) {
844                 nexthop_nh->nh_parent = fi;
845                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
846                 if (!nexthop_nh->nh_pcpu_rth_output)
847                         goto failure;
848         } endfor_nexthops(fi)
849
850         if (cfg->fc_mx) {
851                 struct nlattr *nla;
852                 int remaining;
853
854                 nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
855                         int type = nla_type(nla);
856
857                         if (type) {
858                                 u32 val;
859
860                                 if (type > RTAX_MAX)
861                                         goto err_inval;
862                                 val = nla_get_u32(nla);
863                                 if (type == RTAX_ADVMSS && val > 65535 - 40)
864                                         val = 65535 - 40;
865                                 if (type == RTAX_MTU && val > 65535 - 15)
866                                         val = 65535 - 15;
867                                 fi->fib_metrics[type - 1] = val;
868                         }
869                 }
870         }
871
872         if (cfg->fc_mp) {
873 #ifdef CONFIG_IP_ROUTE_MULTIPATH
874                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg);
875                 if (err != 0)
876                         goto failure;
877                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif)
878                         goto err_inval;
879                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw)
880                         goto err_inval;
881 #ifdef CONFIG_IP_ROUTE_CLASSID
882                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow)
883                         goto err_inval;
884 #endif
885 #else
886                 goto err_inval;
887 #endif
888         } else {
889                 struct fib_nh *nh = fi->fib_nh;
890
891                 nh->nh_oif = cfg->fc_oif;
892                 nh->nh_gw = cfg->fc_gw;
893                 nh->nh_flags = cfg->fc_flags;
894 #ifdef CONFIG_IP_ROUTE_CLASSID
895                 nh->nh_tclassid = cfg->fc_flow;
896                 if (nh->nh_tclassid)
897                         fi->fib_net->ipv4.fib_num_tclassid_users++;
898 #endif
899 #ifdef CONFIG_IP_ROUTE_MULTIPATH
900                 nh->nh_weight = 1;
901 #endif
902         }
903
904         if (fib_props[cfg->fc_type].error) {
905                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
906                         goto err_inval;
907                 goto link_it;
908         } else {
909                 switch (cfg->fc_type) {
910                 case RTN_UNICAST:
911                 case RTN_LOCAL:
912                 case RTN_BROADCAST:
913                 case RTN_ANYCAST:
914                 case RTN_MULTICAST:
915                         break;
916                 default:
917                         goto err_inval;
918                 }
919         }
920
921         if (cfg->fc_scope > RT_SCOPE_HOST)
922                 goto err_inval;
923
924         if (cfg->fc_scope == RT_SCOPE_HOST) {
925                 struct fib_nh *nh = fi->fib_nh;
926
927                 /* Local address is added. */
928                 if (nhs != 1 || nh->nh_gw)
929                         goto err_inval;
930                 nh->nh_scope = RT_SCOPE_NOWHERE;
931                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
932                 err = -ENODEV;
933                 if (nh->nh_dev == NULL)
934                         goto failure;
935         } else {
936                 change_nexthops(fi) {
937                         err = fib_check_nh(cfg, fi, nexthop_nh);
938                         if (err != 0)
939                                 goto failure;
940                 } endfor_nexthops(fi)
941         }
942
943         if (fi->fib_prefsrc) {
944                 if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
945                     fi->fib_prefsrc != cfg->fc_dst)
946                         if (inet_addr_type(net, fi->fib_prefsrc) != RTN_LOCAL)
947                                 goto err_inval;
948         }
949
950         change_nexthops(fi) {
951                 fib_info_update_nh_saddr(net, nexthop_nh);
952         } endfor_nexthops(fi)
953
954 link_it:
955         ofi = fib_find_info(fi);
956         if (ofi) {
957                 fi->fib_dead = 1;
958                 free_fib_info(fi);
959                 ofi->fib_treeref++;
960                 return ofi;
961         }
962
963         fi->fib_treeref++;
964         atomic_inc(&fi->fib_clntref);
965         spin_lock_bh(&fib_info_lock);
966         hlist_add_head(&fi->fib_hash,
967                        &fib_info_hash[fib_info_hashfn(fi)]);
968         if (fi->fib_prefsrc) {
969                 struct hlist_head *head;
970
971                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
972                 hlist_add_head(&fi->fib_lhash, head);
973         }
974         change_nexthops(fi) {
975                 struct hlist_head *head;
976                 unsigned int hash;
977
978                 if (!nexthop_nh->nh_dev)
979                         continue;
980                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
981                 head = &fib_info_devhash[hash];
982                 hlist_add_head(&nexthop_nh->nh_hash, head);
983         } endfor_nexthops(fi)
984         spin_unlock_bh(&fib_info_lock);
985         return fi;
986
987 err_inval:
988         err = -EINVAL;
989
990 failure:
991         if (fi) {
992                 fi->fib_dead = 1;
993                 free_fib_info(fi);
994         }
995
996         return ERR_PTR(err);
997 }
998
999 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1000                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1001                   struct fib_info *fi, unsigned int flags)
1002 {
1003         struct nlmsghdr *nlh;
1004         struct rtmsg *rtm;
1005
1006         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1007         if (nlh == NULL)
1008                 return -EMSGSIZE;
1009
1010         rtm = nlmsg_data(nlh);
1011         rtm->rtm_family = AF_INET;
1012         rtm->rtm_dst_len = dst_len;
1013         rtm->rtm_src_len = 0;
1014         rtm->rtm_tos = tos;
1015         if (tb_id < 256)
1016                 rtm->rtm_table = tb_id;
1017         else
1018                 rtm->rtm_table = RT_TABLE_COMPAT;
1019         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1020                 goto nla_put_failure;
1021         rtm->rtm_type = type;
1022         rtm->rtm_flags = fi->fib_flags;
1023         rtm->rtm_scope = fi->fib_scope;
1024         rtm->rtm_protocol = fi->fib_protocol;
1025
1026         if (rtm->rtm_dst_len &&
1027             nla_put_be32(skb, RTA_DST, dst))
1028                 goto nla_put_failure;
1029         if (fi->fib_priority &&
1030             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1031                 goto nla_put_failure;
1032         if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
1033                 goto nla_put_failure;
1034
1035         if (fi->fib_prefsrc &&
1036             nla_put_be32(skb, RTA_PREFSRC, fi->fib_prefsrc))
1037                 goto nla_put_failure;
1038         if (fi->fib_nhs == 1) {
1039                 if (fi->fib_nh->nh_gw &&
1040                     nla_put_be32(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1041                         goto nla_put_failure;
1042                 if (fi->fib_nh->nh_oif &&
1043                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1044                         goto nla_put_failure;
1045 #ifdef CONFIG_IP_ROUTE_CLASSID
1046                 if (fi->fib_nh[0].nh_tclassid &&
1047                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1048                         goto nla_put_failure;
1049 #endif
1050         }
1051 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1052         if (fi->fib_nhs > 1) {
1053                 struct rtnexthop *rtnh;
1054                 struct nlattr *mp;
1055
1056                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1057                 if (mp == NULL)
1058                         goto nla_put_failure;
1059
1060                 for_nexthops(fi) {
1061                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1062                         if (rtnh == NULL)
1063                                 goto nla_put_failure;
1064
1065                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1066                         rtnh->rtnh_hops = nh->nh_weight - 1;
1067                         rtnh->rtnh_ifindex = nh->nh_oif;
1068
1069                         if (nh->nh_gw &&
1070                             nla_put_be32(skb, RTA_GATEWAY, nh->nh_gw))
1071                                 goto nla_put_failure;
1072 #ifdef CONFIG_IP_ROUTE_CLASSID
1073                         if (nh->nh_tclassid &&
1074                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1075                                 goto nla_put_failure;
1076 #endif
1077                         /* length of rtnetlink header + attributes */
1078                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1079                 } endfor_nexthops(fi);
1080
1081                 nla_nest_end(skb, mp);
1082         }
1083 #endif
1084         return nlmsg_end(skb, nlh);
1085
1086 nla_put_failure:
1087         nlmsg_cancel(skb, nlh);
1088         return -EMSGSIZE;
1089 }
1090
1091 /*
1092  * Update FIB if:
1093  * - local address disappeared -> we must delete all the entries
1094  *   referring to it.
1095  * - device went down -> we must shutdown all nexthops going via it.
1096  */
1097 int fib_sync_down_addr(struct net *net, __be32 local)
1098 {
1099         int ret = 0;
1100         unsigned int hash = fib_laddr_hashfn(local);
1101         struct hlist_head *head = &fib_info_laddrhash[hash];
1102         struct fib_info *fi;
1103
1104         if (fib_info_laddrhash == NULL || local == 0)
1105                 return 0;
1106
1107         hlist_for_each_entry(fi, head, fib_lhash) {
1108                 if (!net_eq(fi->fib_net, net))
1109                         continue;
1110                 if (fi->fib_prefsrc == local) {
1111                         fi->fib_flags |= RTNH_F_DEAD;
1112                         ret++;
1113                 }
1114         }
1115         return ret;
1116 }
1117
1118 int fib_sync_down_dev(struct net_device *dev, int force)
1119 {
1120         int ret = 0;
1121         int scope = RT_SCOPE_NOWHERE;
1122         struct fib_info *prev_fi = NULL;
1123         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1124         struct hlist_head *head = &fib_info_devhash[hash];
1125         struct fib_nh *nh;
1126
1127         if (force)
1128                 scope = -1;
1129
1130         hlist_for_each_entry(nh, head, nh_hash) {
1131                 struct fib_info *fi = nh->nh_parent;
1132                 int dead;
1133
1134                 BUG_ON(!fi->fib_nhs);
1135                 if (nh->nh_dev != dev || fi == prev_fi)
1136                         continue;
1137                 prev_fi = fi;
1138                 dead = 0;
1139                 change_nexthops(fi) {
1140                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1141                                 dead++;
1142                         else if (nexthop_nh->nh_dev == dev &&
1143                                  nexthop_nh->nh_scope != scope) {
1144                                 nexthop_nh->nh_flags |= RTNH_F_DEAD;
1145 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1146                                 spin_lock_bh(&fib_multipath_lock);
1147                                 fi->fib_power -= nexthop_nh->nh_power;
1148                                 nexthop_nh->nh_power = 0;
1149                                 spin_unlock_bh(&fib_multipath_lock);
1150 #endif
1151                                 dead++;
1152                         }
1153 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1154                         if (force > 1 && nexthop_nh->nh_dev == dev) {
1155                                 dead = fi->fib_nhs;
1156                                 break;
1157                         }
1158 #endif
1159                 } endfor_nexthops(fi)
1160                 if (dead == fi->fib_nhs) {
1161                         fi->fib_flags |= RTNH_F_DEAD;
1162                         ret++;
1163                 }
1164         }
1165
1166         return ret;
1167 }
1168
1169 /* Must be invoked inside of an RCU protected region.  */
1170 void fib_select_default(struct fib_result *res)
1171 {
1172         struct fib_info *fi = NULL, *last_resort = NULL;
1173         struct list_head *fa_head = res->fa_head;
1174         struct fib_table *tb = res->table;
1175         int order = -1, last_idx = -1;
1176         struct fib_alias *fa;
1177
1178         list_for_each_entry_rcu(fa, fa_head, fa_list) {
1179                 struct fib_info *next_fi = fa->fa_info;
1180
1181                 if (next_fi->fib_scope != res->scope ||
1182                     fa->fa_type != RTN_UNICAST)
1183                         continue;
1184
1185                 if (next_fi->fib_priority > res->fi->fib_priority)
1186                         break;
1187                 if (!next_fi->fib_nh[0].nh_gw ||
1188                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1189                         continue;
1190
1191                 fib_alias_accessed(fa);
1192
1193                 if (fi == NULL) {
1194                         if (next_fi != res->fi)
1195                                 break;
1196                 } else if (!fib_detect_death(fi, order, &last_resort,
1197                                              &last_idx, tb->tb_default)) {
1198                         fib_result_assign(res, fi);
1199                         tb->tb_default = order;
1200                         goto out;
1201                 }
1202                 fi = next_fi;
1203                 order++;
1204         }
1205
1206         if (order <= 0 || fi == NULL) {
1207                 tb->tb_default = -1;
1208                 goto out;
1209         }
1210
1211         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1212                                 tb->tb_default)) {
1213                 fib_result_assign(res, fi);
1214                 tb->tb_default = order;
1215                 goto out;
1216         }
1217
1218         if (last_idx >= 0)
1219                 fib_result_assign(res, last_resort);
1220         tb->tb_default = last_idx;
1221 out:
1222         return;
1223 }
1224
1225 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1226
1227 /*
1228  * Dead device goes up. We wake up dead nexthops.
1229  * It takes sense only on multipath routes.
1230  */
1231 int fib_sync_up(struct net_device *dev)
1232 {
1233         struct fib_info *prev_fi;
1234         unsigned int hash;
1235         struct hlist_head *head;
1236         struct fib_nh *nh;
1237         int ret;
1238
1239         if (!(dev->flags & IFF_UP))
1240                 return 0;
1241
1242         prev_fi = NULL;
1243         hash = fib_devindex_hashfn(dev->ifindex);
1244         head = &fib_info_devhash[hash];
1245         ret = 0;
1246
1247         hlist_for_each_entry(nh, head, nh_hash) {
1248                 struct fib_info *fi = nh->nh_parent;
1249                 int alive;
1250
1251                 BUG_ON(!fi->fib_nhs);
1252                 if (nh->nh_dev != dev || fi == prev_fi)
1253                         continue;
1254
1255                 prev_fi = fi;
1256                 alive = 0;
1257                 change_nexthops(fi) {
1258                         if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1259                                 alive++;
1260                                 continue;
1261                         }
1262                         if (nexthop_nh->nh_dev == NULL ||
1263                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1264                                 continue;
1265                         if (nexthop_nh->nh_dev != dev ||
1266                             !__in_dev_get_rtnl(dev))
1267                                 continue;
1268                         alive++;
1269                         spin_lock_bh(&fib_multipath_lock);
1270                         nexthop_nh->nh_power = 0;
1271                         nexthop_nh->nh_flags &= ~RTNH_F_DEAD;
1272                         spin_unlock_bh(&fib_multipath_lock);
1273                 } endfor_nexthops(fi)
1274
1275                 if (alive > 0) {
1276                         fi->fib_flags &= ~RTNH_F_DEAD;
1277                         ret++;
1278                 }
1279         }
1280
1281         return ret;
1282 }
1283
1284 /*
1285  * The algorithm is suboptimal, but it provides really
1286  * fair weighted route distribution.
1287  */
1288 void fib_select_multipath(struct fib_result *res)
1289 {
1290         struct fib_info *fi = res->fi;
1291         int w;
1292
1293         spin_lock_bh(&fib_multipath_lock);
1294         if (fi->fib_power <= 0) {
1295                 int power = 0;
1296                 change_nexthops(fi) {
1297                         if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
1298                                 power += nexthop_nh->nh_weight;
1299                                 nexthop_nh->nh_power = nexthop_nh->nh_weight;
1300                         }
1301                 } endfor_nexthops(fi);
1302                 fi->fib_power = power;
1303                 if (power <= 0) {
1304                         spin_unlock_bh(&fib_multipath_lock);
1305                         /* Race condition: route has just become dead. */
1306                         res->nh_sel = 0;
1307                         return;
1308                 }
1309         }
1310
1311
1312         /* w should be random number [0..fi->fib_power-1],
1313          * it is pretty bad approximation.
1314          */
1315
1316         w = jiffies % fi->fib_power;
1317
1318         change_nexthops(fi) {
1319                 if (!(nexthop_nh->nh_flags & RTNH_F_DEAD) &&
1320                     nexthop_nh->nh_power) {
1321                         w -= nexthop_nh->nh_power;
1322                         if (w <= 0) {
1323                                 nexthop_nh->nh_power--;
1324                                 fi->fib_power--;
1325                                 res->nh_sel = nhsel;
1326                                 spin_unlock_bh(&fib_multipath_lock);
1327                                 return;
1328                         }
1329                 }
1330         } endfor_nexthops(fi);
1331
1332         /* Race condition: route has just become dead. */
1333         res->nh_sel = 0;
1334         spin_unlock_bh(&fib_multipath_lock);
1335 }
1336 #endif