Revert "bond: take rcu lock in netpoll_send_skb_on_dev"
[muen/linux.git] / net / core / netpoll.c
1 /*
2  * Common framework for low-level network console, dump, and debugger code
3  *
4  * Sep 8 2003  Matt Mackall <mpm@selenic.com>
5  *
6  * based on the netconsole code from:
7  *
8  * Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
9  * Copyright (C) 2002  Red Hat, Inc.
10  */
11
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14 #include <linux/moduleparam.h>
15 #include <linux/kernel.h>
16 #include <linux/netdevice.h>
17 #include <linux/etherdevice.h>
18 #include <linux/string.h>
19 #include <linux/if_arp.h>
20 #include <linux/inetdevice.h>
21 #include <linux/inet.h>
22 #include <linux/interrupt.h>
23 #include <linux/netpoll.h>
24 #include <linux/sched.h>
25 #include <linux/delay.h>
26 #include <linux/rcupdate.h>
27 #include <linux/workqueue.h>
28 #include <linux/slab.h>
29 #include <linux/export.h>
30 #include <linux/if_vlan.h>
31 #include <net/tcp.h>
32 #include <net/udp.h>
33 #include <net/addrconf.h>
34 #include <net/ndisc.h>
35 #include <net/ip6_checksum.h>
36 #include <asm/unaligned.h>
37 #include <trace/events/napi.h>
38
39 /*
40  * We maintain a small pool of fully-sized skbs, to make sure the
41  * message gets out even in extreme OOM situations.
42  */
43
44 #define MAX_UDP_CHUNK 1460
45 #define MAX_SKBS 32
46
47 static struct sk_buff_head skb_pool;
48
49 DEFINE_STATIC_SRCU(netpoll_srcu);
50
51 #define USEC_PER_POLL   50
52
53 #define MAX_SKB_SIZE                                                    \
54         (sizeof(struct ethhdr) +                                        \
55          sizeof(struct iphdr) +                                         \
56          sizeof(struct udphdr) +                                        \
57          MAX_UDP_CHUNK)
58
59 static void zap_completion_queue(void);
60 static void netpoll_async_cleanup(struct work_struct *work);
61
62 static unsigned int carrier_timeout = 4;
63 module_param(carrier_timeout, uint, 0644);
64
65 #define np_info(np, fmt, ...)                           \
66         pr_info("%s: " fmt, np->name, ##__VA_ARGS__)
67 #define np_err(np, fmt, ...)                            \
68         pr_err("%s: " fmt, np->name, ##__VA_ARGS__)
69 #define np_notice(np, fmt, ...)                         \
70         pr_notice("%s: " fmt, np->name, ##__VA_ARGS__)
71
72 static int netpoll_start_xmit(struct sk_buff *skb, struct net_device *dev,
73                               struct netdev_queue *txq)
74 {
75         int status = NETDEV_TX_OK;
76         netdev_features_t features;
77
78         features = netif_skb_features(skb);
79
80         if (skb_vlan_tag_present(skb) &&
81             !vlan_hw_offload_capable(features, skb->vlan_proto)) {
82                 skb = __vlan_hwaccel_push_inside(skb);
83                 if (unlikely(!skb)) {
84                         /* This is actually a packet drop, but we
85                          * don't want the code that calls this
86                          * function to try and operate on a NULL skb.
87                          */
88                         goto out;
89                 }
90         }
91
92         status = netdev_start_xmit(skb, dev, txq, false);
93
94 out:
95         return status;
96 }
97
98 static void queue_process(struct work_struct *work)
99 {
100         struct netpoll_info *npinfo =
101                 container_of(work, struct netpoll_info, tx_work.work);
102         struct sk_buff *skb;
103         unsigned long flags;
104
105         while ((skb = skb_dequeue(&npinfo->txq))) {
106                 struct net_device *dev = skb->dev;
107                 struct netdev_queue *txq;
108                 unsigned int q_index;
109
110                 if (!netif_device_present(dev) || !netif_running(dev)) {
111                         kfree_skb(skb);
112                         continue;
113                 }
114
115                 local_irq_save(flags);
116                 /* check if skb->queue_mapping is still valid */
117                 q_index = skb_get_queue_mapping(skb);
118                 if (unlikely(q_index >= dev->real_num_tx_queues)) {
119                         q_index = q_index % dev->real_num_tx_queues;
120                         skb_set_queue_mapping(skb, q_index);
121                 }
122                 txq = netdev_get_tx_queue(dev, q_index);
123                 HARD_TX_LOCK(dev, txq, smp_processor_id());
124                 if (netif_xmit_frozen_or_stopped(txq) ||
125                     netpoll_start_xmit(skb, dev, txq) != NETDEV_TX_OK) {
126                         skb_queue_head(&npinfo->txq, skb);
127                         HARD_TX_UNLOCK(dev, txq);
128                         local_irq_restore(flags);
129
130                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
131                         return;
132                 }
133                 HARD_TX_UNLOCK(dev, txq);
134                 local_irq_restore(flags);
135         }
136 }
137
138 static void poll_one_napi(struct napi_struct *napi)
139 {
140         int work;
141
142         /* If we set this bit but see that it has already been set,
143          * that indicates that napi has been disabled and we need
144          * to abort this operation
145          */
146         if (test_and_set_bit(NAPI_STATE_NPSVC, &napi->state))
147                 return;
148
149         /* We explicilty pass the polling call a budget of 0 to
150          * indicate that we are clearing the Tx path only.
151          */
152         work = napi->poll(napi, 0);
153         WARN_ONCE(work, "%pF exceeded budget in poll\n", napi->poll);
154         trace_napi_poll(napi, work, 0);
155
156         clear_bit(NAPI_STATE_NPSVC, &napi->state);
157 }
158
159 static void poll_napi(struct net_device *dev)
160 {
161         struct napi_struct *napi;
162         int cpu = smp_processor_id();
163
164         list_for_each_entry(napi, &dev->napi_list, dev_list) {
165                 if (cmpxchg(&napi->poll_owner, -1, cpu) == -1) {
166                         poll_one_napi(napi);
167                         smp_store_release(&napi->poll_owner, -1);
168                 }
169         }
170 }
171
172 void netpoll_poll_dev(struct net_device *dev)
173 {
174         struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
175         const struct net_device_ops *ops;
176
177         /* Don't do any rx activity if the dev_lock mutex is held
178          * the dev_open/close paths use this to block netpoll activity
179          * while changing device state
180          */
181         if (!ni || down_trylock(&ni->dev_lock))
182                 return;
183
184         if (!netif_running(dev)) {
185                 up(&ni->dev_lock);
186                 return;
187         }
188
189         ops = dev->netdev_ops;
190         if (ops->ndo_poll_controller)
191                 ops->ndo_poll_controller(dev);
192
193         poll_napi(dev);
194
195         up(&ni->dev_lock);
196
197         zap_completion_queue();
198 }
199 EXPORT_SYMBOL(netpoll_poll_dev);
200
201 void netpoll_poll_disable(struct net_device *dev)
202 {
203         struct netpoll_info *ni;
204         int idx;
205         might_sleep();
206         idx = srcu_read_lock(&netpoll_srcu);
207         ni = srcu_dereference(dev->npinfo, &netpoll_srcu);
208         if (ni)
209                 down(&ni->dev_lock);
210         srcu_read_unlock(&netpoll_srcu, idx);
211 }
212 EXPORT_SYMBOL(netpoll_poll_disable);
213
214 void netpoll_poll_enable(struct net_device *dev)
215 {
216         struct netpoll_info *ni;
217         rcu_read_lock();
218         ni = rcu_dereference(dev->npinfo);
219         if (ni)
220                 up(&ni->dev_lock);
221         rcu_read_unlock();
222 }
223 EXPORT_SYMBOL(netpoll_poll_enable);
224
225 static void refill_skbs(void)
226 {
227         struct sk_buff *skb;
228         unsigned long flags;
229
230         spin_lock_irqsave(&skb_pool.lock, flags);
231         while (skb_pool.qlen < MAX_SKBS) {
232                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
233                 if (!skb)
234                         break;
235
236                 __skb_queue_tail(&skb_pool, skb);
237         }
238         spin_unlock_irqrestore(&skb_pool.lock, flags);
239 }
240
241 static void zap_completion_queue(void)
242 {
243         unsigned long flags;
244         struct softnet_data *sd = &get_cpu_var(softnet_data);
245
246         if (sd->completion_queue) {
247                 struct sk_buff *clist;
248
249                 local_irq_save(flags);
250                 clist = sd->completion_queue;
251                 sd->completion_queue = NULL;
252                 local_irq_restore(flags);
253
254                 while (clist != NULL) {
255                         struct sk_buff *skb = clist;
256                         clist = clist->next;
257                         if (!skb_irq_freeable(skb)) {
258                                 refcount_set(&skb->users, 1);
259                                 dev_kfree_skb_any(skb); /* put this one back */
260                         } else {
261                                 __kfree_skb(skb);
262                         }
263                 }
264         }
265
266         put_cpu_var(softnet_data);
267 }
268
269 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
270 {
271         int count = 0;
272         struct sk_buff *skb;
273
274         zap_completion_queue();
275         refill_skbs();
276 repeat:
277
278         skb = alloc_skb(len, GFP_ATOMIC);
279         if (!skb)
280                 skb = skb_dequeue(&skb_pool);
281
282         if (!skb) {
283                 if (++count < 10) {
284                         netpoll_poll_dev(np->dev);
285                         goto repeat;
286                 }
287                 return NULL;
288         }
289
290         refcount_set(&skb->users, 1);
291         skb_reserve(skb, reserve);
292         return skb;
293 }
294
295 static int netpoll_owner_active(struct net_device *dev)
296 {
297         struct napi_struct *napi;
298
299         list_for_each_entry(napi, &dev->napi_list, dev_list) {
300                 if (napi->poll_owner == smp_processor_id())
301                         return 1;
302         }
303         return 0;
304 }
305
306 /* call with IRQ disabled */
307 void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
308                              struct net_device *dev)
309 {
310         int status = NETDEV_TX_BUSY;
311         unsigned long tries;
312         /* It is up to the caller to keep npinfo alive. */
313         struct netpoll_info *npinfo;
314
315         lockdep_assert_irqs_disabled();
316
317         npinfo = rcu_dereference_bh(np->dev->npinfo);
318         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
319                 dev_kfree_skb_irq(skb);
320                 return;
321         }
322
323         /* don't get messages out of order, and no recursion */
324         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
325                 struct netdev_queue *txq;
326
327                 txq = netdev_pick_tx(dev, skb, NULL);
328
329                 /* try until next clock tick */
330                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
331                      tries > 0; --tries) {
332                         if (HARD_TX_TRYLOCK(dev, txq)) {
333                                 if (!netif_xmit_stopped(txq))
334                                         status = netpoll_start_xmit(skb, dev, txq);
335
336                                 HARD_TX_UNLOCK(dev, txq);
337
338                                 if (status == NETDEV_TX_OK)
339                                         break;
340
341                         }
342
343                         /* tickle device maybe there is some cleanup */
344                         netpoll_poll_dev(np->dev);
345
346                         udelay(USEC_PER_POLL);
347                 }
348
349                 WARN_ONCE(!irqs_disabled(),
350                         "netpoll_send_skb_on_dev(): %s enabled interrupts in poll (%pF)\n",
351                         dev->name, dev->netdev_ops->ndo_start_xmit);
352
353         }
354
355         if (status != NETDEV_TX_OK) {
356                 skb_queue_tail(&npinfo->txq, skb);
357                 schedule_delayed_work(&npinfo->tx_work,0);
358         }
359 }
360 EXPORT_SYMBOL(netpoll_send_skb_on_dev);
361
362 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
363 {
364         int total_len, ip_len, udp_len;
365         struct sk_buff *skb;
366         struct udphdr *udph;
367         struct iphdr *iph;
368         struct ethhdr *eth;
369         static atomic_t ip_ident;
370         struct ipv6hdr *ip6h;
371
372         WARN_ON_ONCE(!irqs_disabled());
373
374         udp_len = len + sizeof(*udph);
375         if (np->ipv6)
376                 ip_len = udp_len + sizeof(*ip6h);
377         else
378                 ip_len = udp_len + sizeof(*iph);
379
380         total_len = ip_len + LL_RESERVED_SPACE(np->dev);
381
382         skb = find_skb(np, total_len + np->dev->needed_tailroom,
383                        total_len - len);
384         if (!skb)
385                 return;
386
387         skb_copy_to_linear_data(skb, msg, len);
388         skb_put(skb, len);
389
390         skb_push(skb, sizeof(*udph));
391         skb_reset_transport_header(skb);
392         udph = udp_hdr(skb);
393         udph->source = htons(np->local_port);
394         udph->dest = htons(np->remote_port);
395         udph->len = htons(udp_len);
396
397         if (np->ipv6) {
398                 udph->check = 0;
399                 udph->check = csum_ipv6_magic(&np->local_ip.in6,
400                                               &np->remote_ip.in6,
401                                               udp_len, IPPROTO_UDP,
402                                               csum_partial(udph, udp_len, 0));
403                 if (udph->check == 0)
404                         udph->check = CSUM_MANGLED_0;
405
406                 skb_push(skb, sizeof(*ip6h));
407                 skb_reset_network_header(skb);
408                 ip6h = ipv6_hdr(skb);
409
410                 /* ip6h->version = 6; ip6h->priority = 0; */
411                 put_unaligned(0x60, (unsigned char *)ip6h);
412                 ip6h->flow_lbl[0] = 0;
413                 ip6h->flow_lbl[1] = 0;
414                 ip6h->flow_lbl[2] = 0;
415
416                 ip6h->payload_len = htons(sizeof(struct udphdr) + len);
417                 ip6h->nexthdr = IPPROTO_UDP;
418                 ip6h->hop_limit = 32;
419                 ip6h->saddr = np->local_ip.in6;
420                 ip6h->daddr = np->remote_ip.in6;
421
422                 eth = skb_push(skb, ETH_HLEN);
423                 skb_reset_mac_header(skb);
424                 skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
425         } else {
426                 udph->check = 0;
427                 udph->check = csum_tcpudp_magic(np->local_ip.ip,
428                                                 np->remote_ip.ip,
429                                                 udp_len, IPPROTO_UDP,
430                                                 csum_partial(udph, udp_len, 0));
431                 if (udph->check == 0)
432                         udph->check = CSUM_MANGLED_0;
433
434                 skb_push(skb, sizeof(*iph));
435                 skb_reset_network_header(skb);
436                 iph = ip_hdr(skb);
437
438                 /* iph->version = 4; iph->ihl = 5; */
439                 put_unaligned(0x45, (unsigned char *)iph);
440                 iph->tos      = 0;
441                 put_unaligned(htons(ip_len), &(iph->tot_len));
442                 iph->id       = htons(atomic_inc_return(&ip_ident));
443                 iph->frag_off = 0;
444                 iph->ttl      = 64;
445                 iph->protocol = IPPROTO_UDP;
446                 iph->check    = 0;
447                 put_unaligned(np->local_ip.ip, &(iph->saddr));
448                 put_unaligned(np->remote_ip.ip, &(iph->daddr));
449                 iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
450
451                 eth = skb_push(skb, ETH_HLEN);
452                 skb_reset_mac_header(skb);
453                 skb->protocol = eth->h_proto = htons(ETH_P_IP);
454         }
455
456         ether_addr_copy(eth->h_source, np->dev->dev_addr);
457         ether_addr_copy(eth->h_dest, np->remote_mac);
458
459         skb->dev = np->dev;
460
461         netpoll_send_skb(np, skb);
462 }
463 EXPORT_SYMBOL(netpoll_send_udp);
464
465 void netpoll_print_options(struct netpoll *np)
466 {
467         np_info(np, "local port %d\n", np->local_port);
468         if (np->ipv6)
469                 np_info(np, "local IPv6 address %pI6c\n", &np->local_ip.in6);
470         else
471                 np_info(np, "local IPv4 address %pI4\n", &np->local_ip.ip);
472         np_info(np, "interface '%s'\n", np->dev_name);
473         np_info(np, "remote port %d\n", np->remote_port);
474         if (np->ipv6)
475                 np_info(np, "remote IPv6 address %pI6c\n", &np->remote_ip.in6);
476         else
477                 np_info(np, "remote IPv4 address %pI4\n", &np->remote_ip.ip);
478         np_info(np, "remote ethernet address %pM\n", np->remote_mac);
479 }
480 EXPORT_SYMBOL(netpoll_print_options);
481
482 static int netpoll_parse_ip_addr(const char *str, union inet_addr *addr)
483 {
484         const char *end;
485
486         if (!strchr(str, ':') &&
487             in4_pton(str, -1, (void *)addr, -1, &end) > 0) {
488                 if (!*end)
489                         return 0;
490         }
491         if (in6_pton(str, -1, addr->in6.s6_addr, -1, &end) > 0) {
492 #if IS_ENABLED(CONFIG_IPV6)
493                 if (!*end)
494                         return 1;
495 #else
496                 return -1;
497 #endif
498         }
499         return -1;
500 }
501
502 int netpoll_parse_options(struct netpoll *np, char *opt)
503 {
504         char *cur=opt, *delim;
505         int ipv6;
506         bool ipversion_set = false;
507
508         if (*cur != '@') {
509                 if ((delim = strchr(cur, '@')) == NULL)
510                         goto parse_failed;
511                 *delim = 0;
512                 if (kstrtou16(cur, 10, &np->local_port))
513                         goto parse_failed;
514                 cur = delim;
515         }
516         cur++;
517
518         if (*cur != '/') {
519                 ipversion_set = true;
520                 if ((delim = strchr(cur, '/')) == NULL)
521                         goto parse_failed;
522                 *delim = 0;
523                 ipv6 = netpoll_parse_ip_addr(cur, &np->local_ip);
524                 if (ipv6 < 0)
525                         goto parse_failed;
526                 else
527                         np->ipv6 = (bool)ipv6;
528                 cur = delim;
529         }
530         cur++;
531
532         if (*cur != ',') {
533                 /* parse out dev name */
534                 if ((delim = strchr(cur, ',')) == NULL)
535                         goto parse_failed;
536                 *delim = 0;
537                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
538                 cur = delim;
539         }
540         cur++;
541
542         if (*cur != '@') {
543                 /* dst port */
544                 if ((delim = strchr(cur, '@')) == NULL)
545                         goto parse_failed;
546                 *delim = 0;
547                 if (*cur == ' ' || *cur == '\t')
548                         np_info(np, "warning: whitespace is not allowed\n");
549                 if (kstrtou16(cur, 10, &np->remote_port))
550                         goto parse_failed;
551                 cur = delim;
552         }
553         cur++;
554
555         /* dst ip */
556         if ((delim = strchr(cur, '/')) == NULL)
557                 goto parse_failed;
558         *delim = 0;
559         ipv6 = netpoll_parse_ip_addr(cur, &np->remote_ip);
560         if (ipv6 < 0)
561                 goto parse_failed;
562         else if (ipversion_set && np->ipv6 != (bool)ipv6)
563                 goto parse_failed;
564         else
565                 np->ipv6 = (bool)ipv6;
566         cur = delim + 1;
567
568         if (*cur != 0) {
569                 /* MAC address */
570                 if (!mac_pton(cur, np->remote_mac))
571                         goto parse_failed;
572         }
573
574         netpoll_print_options(np);
575
576         return 0;
577
578  parse_failed:
579         np_info(np, "couldn't parse config at '%s'!\n", cur);
580         return -1;
581 }
582 EXPORT_SYMBOL(netpoll_parse_options);
583
584 int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
585 {
586         struct netpoll_info *npinfo;
587         const struct net_device_ops *ops;
588         int err;
589
590         np->dev = ndev;
591         strlcpy(np->dev_name, ndev->name, IFNAMSIZ);
592         INIT_WORK(&np->cleanup_work, netpoll_async_cleanup);
593
594         if (ndev->priv_flags & IFF_DISABLE_NETPOLL) {
595                 np_err(np, "%s doesn't support polling, aborting\n",
596                        np->dev_name);
597                 err = -ENOTSUPP;
598                 goto out;
599         }
600
601         if (!ndev->npinfo) {
602                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
603                 if (!npinfo) {
604                         err = -ENOMEM;
605                         goto out;
606                 }
607
608                 sema_init(&npinfo->dev_lock, 1);
609                 skb_queue_head_init(&npinfo->txq);
610                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
611
612                 refcount_set(&npinfo->refcnt, 1);
613
614                 ops = np->dev->netdev_ops;
615                 if (ops->ndo_netpoll_setup) {
616                         err = ops->ndo_netpoll_setup(ndev, npinfo);
617                         if (err)
618                                 goto free_npinfo;
619                 }
620         } else {
621                 npinfo = rtnl_dereference(ndev->npinfo);
622                 refcount_inc(&npinfo->refcnt);
623         }
624
625         npinfo->netpoll = np;
626
627         /* last thing to do is link it to the net device structure */
628         rcu_assign_pointer(ndev->npinfo, npinfo);
629
630         return 0;
631
632 free_npinfo:
633         kfree(npinfo);
634 out:
635         return err;
636 }
637 EXPORT_SYMBOL_GPL(__netpoll_setup);
638
639 int netpoll_setup(struct netpoll *np)
640 {
641         struct net_device *ndev = NULL;
642         struct in_device *in_dev;
643         int err;
644
645         rtnl_lock();
646         if (np->dev_name[0]) {
647                 struct net *net = current->nsproxy->net_ns;
648                 ndev = __dev_get_by_name(net, np->dev_name);
649         }
650         if (!ndev) {
651                 np_err(np, "%s doesn't exist, aborting\n", np->dev_name);
652                 err = -ENODEV;
653                 goto unlock;
654         }
655         dev_hold(ndev);
656
657         if (netdev_master_upper_dev_get(ndev)) {
658                 np_err(np, "%s is a slave device, aborting\n", np->dev_name);
659                 err = -EBUSY;
660                 goto put;
661         }
662
663         if (!netif_running(ndev)) {
664                 unsigned long atmost, atleast;
665
666                 np_info(np, "device %s not up yet, forcing it\n", np->dev_name);
667
668                 err = dev_open(ndev);
669
670                 if (err) {
671                         np_err(np, "failed to open %s\n", ndev->name);
672                         goto put;
673                 }
674
675                 rtnl_unlock();
676                 atleast = jiffies + HZ/10;
677                 atmost = jiffies + carrier_timeout * HZ;
678                 while (!netif_carrier_ok(ndev)) {
679                         if (time_after(jiffies, atmost)) {
680                                 np_notice(np, "timeout waiting for carrier\n");
681                                 break;
682                         }
683                         msleep(1);
684                 }
685
686                 /* If carrier appears to come up instantly, we don't
687                  * trust it and pause so that we don't pump all our
688                  * queued console messages into the bitbucket.
689                  */
690
691                 if (time_before(jiffies, atleast)) {
692                         np_notice(np, "carrier detect appears untrustworthy, waiting 4 seconds\n");
693                         msleep(4000);
694                 }
695                 rtnl_lock();
696         }
697
698         if (!np->local_ip.ip) {
699                 if (!np->ipv6) {
700                         in_dev = __in_dev_get_rtnl(ndev);
701
702                         if (!in_dev || !in_dev->ifa_list) {
703                                 np_err(np, "no IP address for %s, aborting\n",
704                                        np->dev_name);
705                                 err = -EDESTADDRREQ;
706                                 goto put;
707                         }
708
709                         np->local_ip.ip = in_dev->ifa_list->ifa_local;
710                         np_info(np, "local IP %pI4\n", &np->local_ip.ip);
711                 } else {
712 #if IS_ENABLED(CONFIG_IPV6)
713                         struct inet6_dev *idev;
714
715                         err = -EDESTADDRREQ;
716                         idev = __in6_dev_get(ndev);
717                         if (idev) {
718                                 struct inet6_ifaddr *ifp;
719
720                                 read_lock_bh(&idev->lock);
721                                 list_for_each_entry(ifp, &idev->addr_list, if_list) {
722                                         if (ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL)
723                                                 continue;
724                                         np->local_ip.in6 = ifp->addr;
725                                         err = 0;
726                                         break;
727                                 }
728                                 read_unlock_bh(&idev->lock);
729                         }
730                         if (err) {
731                                 np_err(np, "no IPv6 address for %s, aborting\n",
732                                        np->dev_name);
733                                 goto put;
734                         } else
735                                 np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
736 #else
737                         np_err(np, "IPv6 is not supported %s, aborting\n",
738                                np->dev_name);
739                         err = -EINVAL;
740                         goto put;
741 #endif
742                 }
743         }
744
745         /* fill up the skb queue */
746         refill_skbs();
747
748         err = __netpoll_setup(np, ndev);
749         if (err)
750                 goto put;
751
752         rtnl_unlock();
753         return 0;
754
755 put:
756         dev_put(ndev);
757 unlock:
758         rtnl_unlock();
759         return err;
760 }
761 EXPORT_SYMBOL(netpoll_setup);
762
763 static int __init netpoll_init(void)
764 {
765         skb_queue_head_init(&skb_pool);
766         return 0;
767 }
768 core_initcall(netpoll_init);
769
770 static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
771 {
772         struct netpoll_info *npinfo =
773                         container_of(rcu_head, struct netpoll_info, rcu);
774
775         skb_queue_purge(&npinfo->txq);
776
777         /* we can't call cancel_delayed_work_sync here, as we are in softirq */
778         cancel_delayed_work(&npinfo->tx_work);
779
780         /* clean after last, unfinished work */
781         __skb_queue_purge(&npinfo->txq);
782         /* now cancel it again */
783         cancel_delayed_work(&npinfo->tx_work);
784         kfree(npinfo);
785 }
786
787 void __netpoll_cleanup(struct netpoll *np)
788 {
789         struct netpoll_info *npinfo;
790
791         /* rtnl_dereference would be preferable here but
792          * rcu_cleanup_netpoll path can put us in here safely without
793          * holding the rtnl, so plain rcu_dereference it is
794          */
795         npinfo = rtnl_dereference(np->dev->npinfo);
796         if (!npinfo)
797                 return;
798
799         synchronize_srcu(&netpoll_srcu);
800
801         if (refcount_dec_and_test(&npinfo->refcnt)) {
802                 const struct net_device_ops *ops;
803
804                 ops = np->dev->netdev_ops;
805                 if (ops->ndo_netpoll_cleanup)
806                         ops->ndo_netpoll_cleanup(np->dev);
807
808                 RCU_INIT_POINTER(np->dev->npinfo, NULL);
809                 call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
810         } else
811                 RCU_INIT_POINTER(np->dev->npinfo, NULL);
812 }
813 EXPORT_SYMBOL_GPL(__netpoll_cleanup);
814
815 static void netpoll_async_cleanup(struct work_struct *work)
816 {
817         struct netpoll *np = container_of(work, struct netpoll, cleanup_work);
818
819         rtnl_lock();
820         __netpoll_cleanup(np);
821         rtnl_unlock();
822         kfree(np);
823 }
824
825 void __netpoll_free_async(struct netpoll *np)
826 {
827         schedule_work(&np->cleanup_work);
828 }
829 EXPORT_SYMBOL_GPL(__netpoll_free_async);
830
831 void netpoll_cleanup(struct netpoll *np)
832 {
833         rtnl_lock();
834         if (!np->dev)
835                 goto out;
836         __netpoll_cleanup(np);
837         dev_put(np->dev);
838         np->dev = NULL;
839 out:
840         rtnl_unlock();
841 }
842 EXPORT_SYMBOL(netpoll_cleanup);