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1/*
2 * net/core/dst.c Protocol independent destination cache.
3 *
4 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
5 *
6 */
7
8#include <linux/bitops.h>
9#include <linux/errno.h>
10#include <linux/init.h>
11#include <linux/kernel.h>
12#include <linux/workqueue.h>
13#include <linux/mm.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <linux/netdevice.h>
17#include <linux/skbuff.h>
18#include <linux/string.h>
19#include <linux/types.h>
20#include <net/net_namespace.h>
21#include <linux/sched.h>
22#include <linux/prefetch.h>
23
24#include <net/dst.h>
25
26/*
27 * Theory of operations:
28 * 1) We use a list, protected by a spinlock, to add
29 * new entries from both BH and non-BH context.
30 * 2) In order to keep spinlock held for a small delay,
31 * we use a second list where are stored long lived
32 * entries, that are handled by the garbage collect thread
33 * fired by a workqueue.
34 * 3) This list is guarded by a mutex,
35 * so that the gc_task and dst_dev_event() can be synchronized.
36 */
37
38/*
39 * We want to keep lock & list close together
40 * to dirty as few cache lines as possible in __dst_free().
41 * As this is not a very strong hint, we dont force an alignment on SMP.
42 */
43static struct {
44 spinlock_t lock;
45 struct dst_entry *list;
46 unsigned long timer_inc;
47 unsigned long timer_expires;
48} dst_garbage = {
49 .lock = __SPIN_LOCK_UNLOCKED(dst_garbage.lock),
50 .timer_inc = DST_GC_MAX,
51};
52static void dst_gc_task(struct work_struct *work);
53static void ___dst_free(struct dst_entry *dst);
54
55static DECLARE_DELAYED_WORK(dst_gc_work, dst_gc_task);
56
57static DEFINE_MUTEX(dst_gc_mutex);
58/*
59 * long lived entries are maintained in this list, guarded by dst_gc_mutex
60 */
61static struct dst_entry *dst_busy_list;
62
63static void dst_gc_task(struct work_struct *work)
64{
65 int delayed = 0;
66 int work_performed = 0;
67 unsigned long expires = ~0L;
68 struct dst_entry *dst, *next, head;
69 struct dst_entry *last = &head;
70
71 mutex_lock(&dst_gc_mutex);
72 next = dst_busy_list;
73
74loop:
75 while ((dst = next) != NULL) {
76 next = dst->next;
77 prefetch(&next->next);
78 cond_resched();
79 if (likely(atomic_read(&dst->__refcnt))) {
80 last->next = dst;
81 last = dst;
82 delayed++;
83 continue;
84 }
85 work_performed++;
86
87 dst = dst_destroy(dst);
88 if (dst) {
89 /* NOHASH and still referenced. Unless it is already
90 * on gc list, invalidate it and add to gc list.
91 *
92 * Note: this is temporary. Actually, NOHASH dst's
93 * must be obsoleted when parent is obsoleted.
94 * But we do not have state "obsoleted, but
95 * referenced by parent", so it is right.
96 */
97 if (dst->obsolete > 1)
98 continue;
99
100 ___dst_free(dst);
101 dst->next = next;
102 next = dst;
103 }
104 }
105
106 spin_lock_bh(&dst_garbage.lock);
107 next = dst_garbage.list;
108 if (next) {
109 dst_garbage.list = NULL;
110 spin_unlock_bh(&dst_garbage.lock);
111 goto loop;
112 }
113 last->next = NULL;
114 dst_busy_list = head.next;
115 if (!dst_busy_list)
116 dst_garbage.timer_inc = DST_GC_MAX;
117 else {
118 /*
119 * if we freed less than 1/10 of delayed entries,
120 * we can sleep longer.
121 */
122 if (work_performed <= delayed/10) {
123 dst_garbage.timer_expires += dst_garbage.timer_inc;
124 if (dst_garbage.timer_expires > DST_GC_MAX)
125 dst_garbage.timer_expires = DST_GC_MAX;
126 dst_garbage.timer_inc += DST_GC_INC;
127 } else {
128 dst_garbage.timer_inc = DST_GC_INC;
129 dst_garbage.timer_expires = DST_GC_MIN;
130 }
131 expires = dst_garbage.timer_expires;
132 /*
133 * if the next desired timer is more than 4 seconds in the
134 * future then round the timer to whole seconds
135 */
136 if (expires > 4*HZ)
137 expires = round_jiffies_relative(expires);
138 schedule_delayed_work(&dst_gc_work, expires);
139 }
140
141 spin_unlock_bh(&dst_garbage.lock);
142 mutex_unlock(&dst_gc_mutex);
143}
144
145int dst_discard(struct sk_buff *skb)
146{
147 kfree_skb(skb);
148 return 0;
149}
150EXPORT_SYMBOL(dst_discard);
151
152const u32 dst_default_metrics[RTAX_MAX];
153
154void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
155 int initial_ref, int initial_obsolete, int flags)
156{
157 struct dst_entry *dst;
158
159 if (ops->gc && dst_entries_get_fast(ops) > ops->gc_thresh) {
160 if (ops->gc(ops))
161 return NULL;
162 }
163 dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
164 if (!dst)
165 return NULL;
166 dst->child = NULL;
167 dst->dev = dev;
168 if (dev)
169 dev_hold(dev);
170 dst->ops = ops;
171 dst_init_metrics(dst, dst_default_metrics, true);
172 dst->expires = 0UL;
173 dst->path = dst;
174 dst->_neighbour = NULL;
175#ifdef CONFIG_XFRM
176 dst->xfrm = NULL;
177#endif
178 dst->input = dst_discard;
179 dst->output = dst_discard;
180 dst->error = 0;
181 dst->obsolete = initial_obsolete;
182 dst->header_len = 0;
183 dst->trailer_len = 0;
184#ifdef CONFIG_IP_ROUTE_CLASSID
185 dst->tclassid = 0;
186#endif
187 atomic_set(&dst->__refcnt, initial_ref);
188 dst->__use = 0;
189 dst->lastuse = jiffies;
190 dst->flags = flags;
191 dst->next = NULL;
192 if (!(flags & DST_NOCOUNT))
193 dst_entries_add(ops, 1);
194 return dst;
195}
196EXPORT_SYMBOL(dst_alloc);
197
198static void ___dst_free(struct dst_entry *dst)
199{
200 /* The first case (dev==NULL) is required, when
201 protocol module is unloaded.
202 */
203 if (dst->dev == NULL || !(dst->dev->flags&IFF_UP))
204 dst->input = dst->output = dst_discard;
205 dst->obsolete = 2;
206}
207
208void __dst_free(struct dst_entry *dst)
209{
210 spin_lock_bh(&dst_garbage.lock);
211 ___dst_free(dst);
212 dst->next = dst_garbage.list;
213 dst_garbage.list = dst;
214 if (dst_garbage.timer_inc > DST_GC_INC) {
215 dst_garbage.timer_inc = DST_GC_INC;
216 dst_garbage.timer_expires = DST_GC_MIN;
217 cancel_delayed_work(&dst_gc_work);
218 schedule_delayed_work(&dst_gc_work, dst_garbage.timer_expires);
219 }
220 spin_unlock_bh(&dst_garbage.lock);
221}
222EXPORT_SYMBOL(__dst_free);
223
224struct dst_entry *dst_destroy(struct dst_entry * dst)
225{
226 struct dst_entry *child;
227 struct neighbour *neigh;
228
229 smp_rmb();
230
231again:
232 neigh = dst->_neighbour;
233 child = dst->child;
234
235 if (neigh) {
236 dst->_neighbour = NULL;
237 neigh_release(neigh);
238 }
239
240 if (!(dst->flags & DST_NOCOUNT))
241 dst_entries_add(dst->ops, -1);
242
243 if (dst->ops->destroy)
244 dst->ops->destroy(dst);
245 if (dst->dev)
246 dev_put(dst->dev);
247 kmem_cache_free(dst->ops->kmem_cachep, dst);
248
249 dst = child;
250 if (dst) {
251 int nohash = dst->flags & DST_NOHASH;
252
253 if (atomic_dec_and_test(&dst->__refcnt)) {
254 /* We were real parent of this dst, so kill child. */
255 if (nohash)
256 goto again;
257 } else {
258 /* Child is still referenced, return it for freeing. */
259 if (nohash)
260 return dst;
261 /* Child is still in his hash table */
262 }
263 }
264 return NULL;
265}
266EXPORT_SYMBOL(dst_destroy);
267
268void dst_release(struct dst_entry *dst)
269{
270 if (dst) {
271 int newrefcnt;
272
273 newrefcnt = atomic_dec_return(&dst->__refcnt);
274 WARN_ON(newrefcnt < 0);
275 if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt) {
276 dst = dst_destroy(dst);
277 if (dst)
278 __dst_free(dst);
279 }
280 }
281}
282EXPORT_SYMBOL(dst_release);
283
284u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
285{
286 u32 *p = kmalloc(sizeof(u32) * RTAX_MAX, GFP_ATOMIC);
287
288 if (p) {
289 u32 *old_p = __DST_METRICS_PTR(old);
290 unsigned long prev, new;
291
292 memcpy(p, old_p, sizeof(u32) * RTAX_MAX);
293
294 new = (unsigned long) p;
295 prev = cmpxchg(&dst->_metrics, old, new);
296
297 if (prev != old) {
298 kfree(p);
299 p = __DST_METRICS_PTR(prev);
300 if (prev & DST_METRICS_READ_ONLY)
301 p = NULL;
302 }
303 }
304 return p;
305}
306EXPORT_SYMBOL(dst_cow_metrics_generic);
307
308/* Caller asserts that dst_metrics_read_only(dst) is false. */
309void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old)
310{
311 unsigned long prev, new;
312
313 new = ((unsigned long) dst_default_metrics) | DST_METRICS_READ_ONLY;
314 prev = cmpxchg(&dst->_metrics, old, new);
315 if (prev == old)
316 kfree(__DST_METRICS_PTR(old));
317}
318EXPORT_SYMBOL(__dst_destroy_metrics_generic);
319
320/**
321 * skb_dst_set_noref - sets skb dst, without a reference
322 * @skb: buffer
323 * @dst: dst entry
324 *
325 * Sets skb dst, assuming a reference was not taken on dst
326 * skb_dst_drop() should not dst_release() this dst
327 */
328void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
329{
330 WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
331 /* If dst not in cache, we must take a reference, because
332 * dst_release() will destroy dst as soon as its refcount becomes zero
333 */
334 if (unlikely(dst->flags & DST_NOCACHE)) {
335 dst_hold(dst);
336 skb_dst_set(skb, dst);
337 } else {
338 skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
339 }
340}
341EXPORT_SYMBOL(skb_dst_set_noref);
342
343/* Dirty hack. We did it in 2.2 (in __dst_free),
344 * we have _very_ good reasons not to repeat
345 * this mistake in 2.3, but we have no choice
346 * now. _It_ _is_ _explicit_ _deliberate_
347 * _race_ _condition_.
348 *
349 * Commented and originally written by Alexey.
350 */
351static void dst_ifdown(struct dst_entry *dst, struct net_device *dev,
352 int unregister)
353{
354 if (dst->ops->ifdown)
355 dst->ops->ifdown(dst, dev, unregister);
356
357 if (dev != dst->dev)
358 return;
359
360 if (!unregister) {
361 dst->input = dst->output = dst_discard;
362 } else {
363 dst->dev = dev_net(dst->dev)->loopback_dev;
364 dev_hold(dst->dev);
365 dev_put(dev);
366 if (dst->_neighbour && dst->_neighbour->dev == dev) {
367 dst->_neighbour->dev = dst->dev;
368 dev_hold(dst->dev);
369 dev_put(dev);
370 }
371 }
372}
373
374static int dst_dev_event(struct notifier_block *this, unsigned long event,
375 void *ptr)
376{
377 struct net_device *dev = ptr;
378 struct dst_entry *dst, *last = NULL;
379
380 switch (event) {
381 case NETDEV_UNREGISTER:
382 case NETDEV_DOWN:
383 mutex_lock(&dst_gc_mutex);
384 for (dst = dst_busy_list; dst; dst = dst->next) {
385 last = dst;
386 dst_ifdown(dst, dev, event != NETDEV_DOWN);
387 }
388
389 spin_lock_bh(&dst_garbage.lock);
390 dst = dst_garbage.list;
391 dst_garbage.list = NULL;
392 spin_unlock_bh(&dst_garbage.lock);
393
394 if (last)
395 last->next = dst;
396 else
397 dst_busy_list = dst;
398 for (; dst; dst = dst->next)
399 dst_ifdown(dst, dev, event != NETDEV_DOWN);
400 mutex_unlock(&dst_gc_mutex);
401 break;
402 }
403 return NOTIFY_DONE;
404}
405
406static struct notifier_block dst_dev_notifier = {
407 .notifier_call = dst_dev_event,
408 .priority = -10, /* must be called after other network notifiers */
409};
410
411void __init dst_init(void)
412{
413 register_netdevice_notifier(&dst_dev_notifier);
414}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * net/core/dst.c Protocol independent destination cache.
4 *
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 *
7 */
8
9#include <linux/bitops.h>
10#include <linux/errno.h>
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/workqueue.h>
14#include <linux/mm.h>
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <linux/netdevice.h>
18#include <linux/skbuff.h>
19#include <linux/string.h>
20#include <linux/types.h>
21#include <net/net_namespace.h>
22#include <linux/sched.h>
23#include <linux/prefetch.h>
24#include <net/lwtunnel.h>
25#include <net/xfrm.h>
26
27#include <net/dst.h>
28#include <net/dst_metadata.h>
29
30int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
31{
32 kfree_skb(skb);
33 return 0;
34}
35EXPORT_SYMBOL(dst_discard_out);
36
37const struct dst_metrics dst_default_metrics = {
38 /* This initializer is needed to force linker to place this variable
39 * into const section. Otherwise it might end into bss section.
40 * We really want to avoid false sharing on this variable, and catch
41 * any writes on it.
42 */
43 .refcnt = REFCOUNT_INIT(1),
44};
45EXPORT_SYMBOL(dst_default_metrics);
46
47void dst_init(struct dst_entry *dst, struct dst_ops *ops,
48 struct net_device *dev, int initial_ref, int initial_obsolete,
49 unsigned short flags)
50{
51 dst->dev = dev;
52 if (dev)
53 dev_hold(dev);
54 dst->ops = ops;
55 dst_init_metrics(dst, dst_default_metrics.metrics, true);
56 dst->expires = 0UL;
57#ifdef CONFIG_XFRM
58 dst->xfrm = NULL;
59#endif
60 dst->input = dst_discard;
61 dst->output = dst_discard_out;
62 dst->error = 0;
63 dst->obsolete = initial_obsolete;
64 dst->header_len = 0;
65 dst->trailer_len = 0;
66#ifdef CONFIG_IP_ROUTE_CLASSID
67 dst->tclassid = 0;
68#endif
69 dst->lwtstate = NULL;
70 atomic_set(&dst->__refcnt, initial_ref);
71 dst->__use = 0;
72 dst->lastuse = jiffies;
73 dst->flags = flags;
74 if (!(flags & DST_NOCOUNT))
75 dst_entries_add(ops, 1);
76}
77EXPORT_SYMBOL(dst_init);
78
79void *dst_alloc(struct dst_ops *ops, struct net_device *dev,
80 int initial_ref, int initial_obsolete, unsigned short flags)
81{
82 struct dst_entry *dst;
83
84 if (ops->gc &&
85 !(flags & DST_NOCOUNT) &&
86 dst_entries_get_fast(ops) > ops->gc_thresh) {
87 if (ops->gc(ops)) {
88 pr_notice_ratelimited("Route cache is full: consider increasing sysctl net.ipv6.route.max_size.\n");
89 return NULL;
90 }
91 }
92
93 dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC);
94 if (!dst)
95 return NULL;
96
97 dst_init(dst, ops, dev, initial_ref, initial_obsolete, flags);
98
99 return dst;
100}
101EXPORT_SYMBOL(dst_alloc);
102
103struct dst_entry *dst_destroy(struct dst_entry * dst)
104{
105 struct dst_entry *child = NULL;
106
107 smp_rmb();
108
109#ifdef CONFIG_XFRM
110 if (dst->xfrm) {
111 struct xfrm_dst *xdst = (struct xfrm_dst *) dst;
112
113 child = xdst->child;
114 }
115#endif
116 if (!(dst->flags & DST_NOCOUNT))
117 dst_entries_add(dst->ops, -1);
118
119 if (dst->ops->destroy)
120 dst->ops->destroy(dst);
121 if (dst->dev)
122 dev_put(dst->dev);
123
124 lwtstate_put(dst->lwtstate);
125
126 if (dst->flags & DST_METADATA)
127 metadata_dst_free((struct metadata_dst *)dst);
128 else
129 kmem_cache_free(dst->ops->kmem_cachep, dst);
130
131 dst = child;
132 if (dst)
133 dst_release_immediate(dst);
134 return NULL;
135}
136EXPORT_SYMBOL(dst_destroy);
137
138static void dst_destroy_rcu(struct rcu_head *head)
139{
140 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head);
141
142 dst = dst_destroy(dst);
143}
144
145/* Operations to mark dst as DEAD and clean up the net device referenced
146 * by dst:
147 * 1. put the dst under blackhole interface and discard all tx/rx packets
148 * on this route.
149 * 2. release the net_device
150 * This function should be called when removing routes from the fib tree
151 * in preparation for a NETDEV_DOWN/NETDEV_UNREGISTER event and also to
152 * make the next dst_ops->check() fail.
153 */
154void dst_dev_put(struct dst_entry *dst)
155{
156 struct net_device *dev = dst->dev;
157
158 dst->obsolete = DST_OBSOLETE_DEAD;
159 if (dst->ops->ifdown)
160 dst->ops->ifdown(dst, dev, true);
161 dst->input = dst_discard;
162 dst->output = dst_discard_out;
163 dst->dev = blackhole_netdev;
164 dev_hold(dst->dev);
165 dev_put(dev);
166}
167EXPORT_SYMBOL(dst_dev_put);
168
169void dst_release(struct dst_entry *dst)
170{
171 if (dst) {
172 int newrefcnt;
173
174 newrefcnt = atomic_dec_return(&dst->__refcnt);
175 if (WARN_ONCE(newrefcnt < 0, "dst_release underflow"))
176 net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
177 __func__, dst, newrefcnt);
178 if (!newrefcnt)
179 call_rcu(&dst->rcu_head, dst_destroy_rcu);
180 }
181}
182EXPORT_SYMBOL(dst_release);
183
184void dst_release_immediate(struct dst_entry *dst)
185{
186 if (dst) {
187 int newrefcnt;
188
189 newrefcnt = atomic_dec_return(&dst->__refcnt);
190 if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow"))
191 net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
192 __func__, dst, newrefcnt);
193 if (!newrefcnt)
194 dst_destroy(dst);
195 }
196}
197EXPORT_SYMBOL(dst_release_immediate);
198
199u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
200{
201 struct dst_metrics *p = kmalloc(sizeof(*p), GFP_ATOMIC);
202
203 if (p) {
204 struct dst_metrics *old_p = (struct dst_metrics *)__DST_METRICS_PTR(old);
205 unsigned long prev, new;
206
207 refcount_set(&p->refcnt, 1);
208 memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));
209
210 new = (unsigned long) p;
211 prev = cmpxchg(&dst->_metrics, old, new);
212
213 if (prev != old) {
214 kfree(p);
215 p = (struct dst_metrics *)__DST_METRICS_PTR(prev);
216 if (prev & DST_METRICS_READ_ONLY)
217 p = NULL;
218 } else if (prev & DST_METRICS_REFCOUNTED) {
219 if (refcount_dec_and_test(&old_p->refcnt))
220 kfree(old_p);
221 }
222 }
223 BUILD_BUG_ON(offsetof(struct dst_metrics, metrics) != 0);
224 return (u32 *)p;
225}
226EXPORT_SYMBOL(dst_cow_metrics_generic);
227
228/* Caller asserts that dst_metrics_read_only(dst) is false. */
229void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old)
230{
231 unsigned long prev, new;
232
233 new = ((unsigned long) &dst_default_metrics) | DST_METRICS_READ_ONLY;
234 prev = cmpxchg(&dst->_metrics, old, new);
235 if (prev == old)
236 kfree(__DST_METRICS_PTR(old));
237}
238EXPORT_SYMBOL(__dst_destroy_metrics_generic);
239
240static struct dst_ops md_dst_ops = {
241 .family = AF_UNSPEC,
242};
243
244static int dst_md_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb)
245{
246 WARN_ONCE(1, "Attempting to call output on metadata dst\n");
247 kfree_skb(skb);
248 return 0;
249}
250
251static int dst_md_discard(struct sk_buff *skb)
252{
253 WARN_ONCE(1, "Attempting to call input on metadata dst\n");
254 kfree_skb(skb);
255 return 0;
256}
257
258static void __metadata_dst_init(struct metadata_dst *md_dst,
259 enum metadata_type type, u8 optslen)
260
261{
262 struct dst_entry *dst;
263
264 dst = &md_dst->dst;
265 dst_init(dst, &md_dst_ops, NULL, 1, DST_OBSOLETE_NONE,
266 DST_METADATA | DST_NOCOUNT);
267
268 dst->input = dst_md_discard;
269 dst->output = dst_md_discard_out;
270
271 memset(dst + 1, 0, sizeof(*md_dst) + optslen - sizeof(*dst));
272 md_dst->type = type;
273}
274
275struct metadata_dst *metadata_dst_alloc(u8 optslen, enum metadata_type type,
276 gfp_t flags)
277{
278 struct metadata_dst *md_dst;
279
280 md_dst = kmalloc(sizeof(*md_dst) + optslen, flags);
281 if (!md_dst)
282 return NULL;
283
284 __metadata_dst_init(md_dst, type, optslen);
285
286 return md_dst;
287}
288EXPORT_SYMBOL_GPL(metadata_dst_alloc);
289
290void metadata_dst_free(struct metadata_dst *md_dst)
291{
292#ifdef CONFIG_DST_CACHE
293 if (md_dst->type == METADATA_IP_TUNNEL)
294 dst_cache_destroy(&md_dst->u.tun_info.dst_cache);
295#endif
296 kfree(md_dst);
297}
298EXPORT_SYMBOL_GPL(metadata_dst_free);
299
300struct metadata_dst __percpu *
301metadata_dst_alloc_percpu(u8 optslen, enum metadata_type type, gfp_t flags)
302{
303 int cpu;
304 struct metadata_dst __percpu *md_dst;
305
306 md_dst = __alloc_percpu_gfp(sizeof(struct metadata_dst) + optslen,
307 __alignof__(struct metadata_dst), flags);
308 if (!md_dst)
309 return NULL;
310
311 for_each_possible_cpu(cpu)
312 __metadata_dst_init(per_cpu_ptr(md_dst, cpu), type, optslen);
313
314 return md_dst;
315}
316EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu);
317
318void metadata_dst_free_percpu(struct metadata_dst __percpu *md_dst)
319{
320#ifdef CONFIG_DST_CACHE
321 int cpu;
322
323 for_each_possible_cpu(cpu) {
324 struct metadata_dst *one_md_dst = per_cpu_ptr(md_dst, cpu);
325
326 if (one_md_dst->type == METADATA_IP_TUNNEL)
327 dst_cache_destroy(&one_md_dst->u.tun_info.dst_cache);
328 }
329#endif
330 free_percpu(md_dst);
331}
332EXPORT_SYMBOL_GPL(metadata_dst_free_percpu);