9675f312830dd762bcd530eee90569de5a89b320
[linux-2.6.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 #include <linux/netdevice.h>
13 #include <linux/etherdevice.h>
14 #include <linux/string.h>
15 #include <linux/if_arp.h>
16 #include <linux/inetdevice.h>
17 #include <linux/inet.h>
18 #include <linux/interrupt.h>
19 #include <linux/netpoll.h>
20 #include <linux/sched.h>
21 #include <linux/delay.h>
22 #include <linux/rcupdate.h>
23 #include <linux/workqueue.h>
24 #include <net/tcp.h>
25 #include <net/udp.h>
26 #include <asm/unaligned.h>
27 #include <trace/events/napi.h>
28
29 /*
30  * We maintain a small pool of fully-sized skbs, to make sure the
31  * message gets out even in extreme OOM situations.
32  */
33
34 #define MAX_UDP_CHUNK 1460
35 #define MAX_SKBS 32
36 #define MAX_QUEUE_DEPTH (MAX_SKBS / 2)
37
38 static struct sk_buff_head skb_pool;
39
40 static atomic_t trapped;
41
42 #define USEC_PER_POLL   50
43 #define NETPOLL_RX_ENABLED  1
44 #define NETPOLL_RX_DROP     2
45
46 #define MAX_SKB_SIZE \
47                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
48                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
49
50 static void zap_completion_queue(void);
51 static void arp_reply(struct sk_buff *skb);
52
53 static void queue_process(struct work_struct *work)
54 {
55         struct netpoll_info *npinfo =
56                 container_of(work, struct netpoll_info, tx_work.work);
57         struct sk_buff *skb;
58         unsigned long flags;
59
60         while ((skb = skb_dequeue(&npinfo->txq))) {
61                 struct net_device *dev = skb->dev;
62                 const struct net_device_ops *ops = dev->netdev_ops;
63                 struct netdev_queue *txq;
64
65                 if (!netif_device_present(dev) || !netif_running(dev)) {
66                         __kfree_skb(skb);
67                         continue;
68                 }
69
70                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
71
72                 local_irq_save(flags);
73                 __netif_tx_lock(txq, smp_processor_id());
74                 if (netif_tx_queue_stopped(txq) ||
75                     netif_tx_queue_frozen(txq) ||
76                     ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
77                         skb_queue_head(&npinfo->txq, skb);
78                         __netif_tx_unlock(txq);
79                         local_irq_restore(flags);
80
81                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
82                         return;
83                 }
84                 __netif_tx_unlock(txq);
85                 local_irq_restore(flags);
86         }
87 }
88
89 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
90                             unsigned short ulen, __be32 saddr, __be32 daddr)
91 {
92         __wsum psum;
93
94         if (uh->check == 0 || skb_csum_unnecessary(skb))
95                 return 0;
96
97         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
98
99         if (skb->ip_summed == CHECKSUM_COMPLETE &&
100             !csum_fold(csum_add(psum, skb->csum)))
101                 return 0;
102
103         skb->csum = psum;
104
105         return __skb_checksum_complete(skb);
106 }
107
108 /*
109  * Check whether delayed processing was scheduled for our NIC. If so,
110  * we attempt to grab the poll lock and use ->poll() to pump the card.
111  * If this fails, either we've recursed in ->poll() or it's already
112  * running on another CPU.
113  *
114  * Note: we don't mask interrupts with this lock because we're using
115  * trylock here and interrupts are already disabled in the softirq
116  * case. Further, we test the poll_owner to avoid recursion on UP
117  * systems where the lock doesn't exist.
118  *
119  * In cases where there is bi-directional communications, reading only
120  * one message at a time can lead to packets being dropped by the
121  * network adapter, forcing superfluous retries and possibly timeouts.
122  * Thus, we set our budget to greater than 1.
123  */
124 static int poll_one_napi(struct netpoll_info *npinfo,
125                          struct napi_struct *napi, int budget)
126 {
127         int work;
128
129         /* net_rx_action's ->poll() invocations and our's are
130          * synchronized by this test which is only made while
131          * holding the napi->poll_lock.
132          */
133         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
134                 return budget;
135
136         npinfo->rx_flags |= NETPOLL_RX_DROP;
137         atomic_inc(&trapped);
138         set_bit(NAPI_STATE_NPSVC, &napi->state);
139
140         work = napi->poll(napi, budget);
141         trace_napi_poll(napi);
142
143         clear_bit(NAPI_STATE_NPSVC, &napi->state);
144         atomic_dec(&trapped);
145         npinfo->rx_flags &= ~NETPOLL_RX_DROP;
146
147         return budget - work;
148 }
149
150 static void poll_napi(struct net_device *dev)
151 {
152         struct napi_struct *napi;
153         int budget = 16;
154
155         list_for_each_entry(napi, &dev->napi_list, dev_list) {
156                 if (napi->poll_owner != smp_processor_id() &&
157                     spin_trylock(&napi->poll_lock)) {
158                         budget = poll_one_napi(dev->npinfo, napi, budget);
159                         spin_unlock(&napi->poll_lock);
160
161                         if (!budget)
162                                 break;
163                 }
164         }
165 }
166
167 static void service_arp_queue(struct netpoll_info *npi)
168 {
169         if (npi) {
170                 struct sk_buff *skb;
171
172                 while ((skb = skb_dequeue(&npi->arp_tx)))
173                         arp_reply(skb);
174         }
175 }
176
177 void netpoll_poll(struct netpoll *np)
178 {
179         struct net_device *dev = np->dev;
180         const struct net_device_ops *ops;
181
182         if (!dev || !netif_running(dev))
183                 return;
184
185         ops = dev->netdev_ops;
186         if (!ops->ndo_poll_controller)
187                 return;
188
189         /* Process pending work on NIC */
190         ops->ndo_poll_controller(dev);
191
192         poll_napi(dev);
193
194         service_arp_queue(dev->npinfo);
195
196         zap_completion_queue();
197 }
198
199 static void refill_skbs(void)
200 {
201         struct sk_buff *skb;
202         unsigned long flags;
203
204         spin_lock_irqsave(&skb_pool.lock, flags);
205         while (skb_pool.qlen < MAX_SKBS) {
206                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
207                 if (!skb)
208                         break;
209
210                 __skb_queue_tail(&skb_pool, skb);
211         }
212         spin_unlock_irqrestore(&skb_pool.lock, flags);
213 }
214
215 static void zap_completion_queue(void)
216 {
217         unsigned long flags;
218         struct softnet_data *sd = &get_cpu_var(softnet_data);
219
220         if (sd->completion_queue) {
221                 struct sk_buff *clist;
222
223                 local_irq_save(flags);
224                 clist = sd->completion_queue;
225                 sd->completion_queue = NULL;
226                 local_irq_restore(flags);
227
228                 while (clist != NULL) {
229                         struct sk_buff *skb = clist;
230                         clist = clist->next;
231                         if (skb->destructor) {
232                                 atomic_inc(&skb->users);
233                                 dev_kfree_skb_any(skb); /* put this one back */
234                         } else {
235                                 __kfree_skb(skb);
236                         }
237                 }
238         }
239
240         put_cpu_var(softnet_data);
241 }
242
243 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
244 {
245         int count = 0;
246         struct sk_buff *skb;
247
248         zap_completion_queue();
249         refill_skbs();
250 repeat:
251
252         skb = alloc_skb(len, GFP_ATOMIC);
253         if (!skb)
254                 skb = skb_dequeue(&skb_pool);
255
256         if (!skb) {
257                 if (++count < 10) {
258                         netpoll_poll(np);
259                         goto repeat;
260                 }
261                 return NULL;
262         }
263
264         atomic_set(&skb->users, 1);
265         skb_reserve(skb, reserve);
266         return skb;
267 }
268
269 static int netpoll_owner_active(struct net_device *dev)
270 {
271         struct napi_struct *napi;
272
273         list_for_each_entry(napi, &dev->napi_list, dev_list) {
274                 if (napi->poll_owner == smp_processor_id())
275                         return 1;
276         }
277         return 0;
278 }
279
280 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
281 {
282         int status = NETDEV_TX_BUSY;
283         unsigned long tries;
284         struct net_device *dev = np->dev;
285         const struct net_device_ops *ops = dev->netdev_ops;
286         struct netpoll_info *npinfo = np->dev->npinfo;
287
288         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
289                 __kfree_skb(skb);
290                 return;
291         }
292
293         /* don't get messages out of order, and no recursion */
294         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
295                 struct netdev_queue *txq;
296                 unsigned long flags;
297
298                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
299
300                 local_irq_save(flags);
301                 /* try until next clock tick */
302                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
303                      tries > 0; --tries) {
304                         if (__netif_tx_trylock(txq)) {
305                                 if (!netif_tx_queue_stopped(txq)) {
306                                         status = ops->ndo_start_xmit(skb, dev);
307                                         if (status == NETDEV_TX_OK)
308                                                 txq_trans_update(txq);
309                                 }
310                                 __netif_tx_unlock(txq);
311
312                                 if (status == NETDEV_TX_OK)
313                                         break;
314
315                         }
316
317                         /* tickle device maybe there is some cleanup */
318                         netpoll_poll(np);
319
320                         udelay(USEC_PER_POLL);
321                 }
322                 local_irq_restore(flags);
323         }
324
325         if (status != NETDEV_TX_OK) {
326                 skb_queue_tail(&npinfo->txq, skb);
327                 schedule_delayed_work(&npinfo->tx_work,0);
328         }
329 }
330
331 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
332 {
333         int total_len, eth_len, ip_len, udp_len;
334         struct sk_buff *skb;
335         struct udphdr *udph;
336         struct iphdr *iph;
337         struct ethhdr *eth;
338
339         udp_len = len + sizeof(*udph);
340         ip_len = eth_len = udp_len + sizeof(*iph);
341         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
342
343         skb = find_skb(np, total_len, total_len - len);
344         if (!skb)
345                 return;
346
347         skb_copy_to_linear_data(skb, msg, len);
348         skb->len += len;
349
350         skb_push(skb, sizeof(*udph));
351         skb_reset_transport_header(skb);
352         udph = udp_hdr(skb);
353         udph->source = htons(np->local_port);
354         udph->dest = htons(np->remote_port);
355         udph->len = htons(udp_len);
356         udph->check = 0;
357         udph->check = csum_tcpudp_magic(np->local_ip,
358                                         np->remote_ip,
359                                         udp_len, IPPROTO_UDP,
360                                         csum_partial(udph, udp_len, 0));
361         if (udph->check == 0)
362                 udph->check = CSUM_MANGLED_0;
363
364         skb_push(skb, sizeof(*iph));
365         skb_reset_network_header(skb);
366         iph = ip_hdr(skb);
367
368         /* iph->version = 4; iph->ihl = 5; */
369         put_unaligned(0x45, (unsigned char *)iph);
370         iph->tos      = 0;
371         put_unaligned(htons(ip_len), &(iph->tot_len));
372         iph->id       = 0;
373         iph->frag_off = 0;
374         iph->ttl      = 64;
375         iph->protocol = IPPROTO_UDP;
376         iph->check    = 0;
377         put_unaligned(np->local_ip, &(iph->saddr));
378         put_unaligned(np->remote_ip, &(iph->daddr));
379         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
380
381         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
382         skb_reset_mac_header(skb);
383         skb->protocol = eth->h_proto = htons(ETH_P_IP);
384         memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
385         memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
386
387         skb->dev = np->dev;
388
389         netpoll_send_skb(np, skb);
390 }
391
392 static void arp_reply(struct sk_buff *skb)
393 {
394         struct netpoll_info *npinfo = skb->dev->npinfo;
395         struct arphdr *arp;
396         unsigned char *arp_ptr;
397         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
398         __be32 sip, tip;
399         unsigned char *sha;
400         struct sk_buff *send_skb;
401         struct netpoll *np = NULL;
402
403         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
404                 np = npinfo->rx_np;
405         if (!np)
406                 return;
407
408         /* No arp on this interface */
409         if (skb->dev->flags & IFF_NOARP)
410                 return;
411
412         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
413                 return;
414
415         skb_reset_network_header(skb);
416         skb_reset_transport_header(skb);
417         arp = arp_hdr(skb);
418
419         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
420              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
421             arp->ar_pro != htons(ETH_P_IP) ||
422             arp->ar_op != htons(ARPOP_REQUEST))
423                 return;
424
425         arp_ptr = (unsigned char *)(arp+1);
426         /* save the location of the src hw addr */
427         sha = arp_ptr;
428         arp_ptr += skb->dev->addr_len;
429         memcpy(&sip, arp_ptr, 4);
430         arp_ptr += 4;
431         /* if we actually cared about dst hw addr, it would get copied here */
432         arp_ptr += skb->dev->addr_len;
433         memcpy(&tip, arp_ptr, 4);
434
435         /* Should we ignore arp? */
436         if (tip != np->local_ip ||
437             ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
438                 return;
439
440         size = arp_hdr_len(skb->dev);
441         send_skb = find_skb(np, size + LL_ALLOCATED_SPACE(np->dev),
442                             LL_RESERVED_SPACE(np->dev));
443
444         if (!send_skb)
445                 return;
446
447         skb_reset_network_header(send_skb);
448         arp = (struct arphdr *) skb_put(send_skb, size);
449         send_skb->dev = skb->dev;
450         send_skb->protocol = htons(ETH_P_ARP);
451
452         /* Fill the device header for the ARP frame */
453         if (dev_hard_header(send_skb, skb->dev, ptype,
454                             sha, np->dev->dev_addr,
455                             send_skb->len) < 0) {
456                 kfree_skb(send_skb);
457                 return;
458         }
459
460         /*
461          * Fill out the arp protocol part.
462          *
463          * we only support ethernet device type,
464          * which (according to RFC 1390) should always equal 1 (Ethernet).
465          */
466
467         arp->ar_hrd = htons(np->dev->type);
468         arp->ar_pro = htons(ETH_P_IP);
469         arp->ar_hln = np->dev->addr_len;
470         arp->ar_pln = 4;
471         arp->ar_op = htons(type);
472
473         arp_ptr=(unsigned char *)(arp + 1);
474         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
475         arp_ptr += np->dev->addr_len;
476         memcpy(arp_ptr, &tip, 4);
477         arp_ptr += 4;
478         memcpy(arp_ptr, sha, np->dev->addr_len);
479         arp_ptr += np->dev->addr_len;
480         memcpy(arp_ptr, &sip, 4);
481
482         netpoll_send_skb(np, send_skb);
483 }
484
485 int __netpoll_rx(struct sk_buff *skb)
486 {
487         int proto, len, ulen;
488         struct iphdr *iph;
489         struct udphdr *uh;
490         struct netpoll_info *npi = skb->dev->npinfo;
491         struct netpoll *np = npi->rx_np;
492
493         if (!np)
494                 goto out;
495         if (skb->dev->type != ARPHRD_ETHER)
496                 goto out;
497
498         /* check if netpoll clients need ARP */
499         if (skb->protocol == htons(ETH_P_ARP) &&
500             atomic_read(&trapped)) {
501                 skb_queue_tail(&npi->arp_tx, skb);
502                 return 1;
503         }
504
505         proto = ntohs(eth_hdr(skb)->h_proto);
506         if (proto != ETH_P_IP)
507                 goto out;
508         if (skb->pkt_type == PACKET_OTHERHOST)
509                 goto out;
510         if (skb_shared(skb))
511                 goto out;
512
513         iph = (struct iphdr *)skb->data;
514         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
515                 goto out;
516         if (iph->ihl < 5 || iph->version != 4)
517                 goto out;
518         if (!pskb_may_pull(skb, iph->ihl*4))
519                 goto out;
520         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
521                 goto out;
522
523         len = ntohs(iph->tot_len);
524         if (skb->len < len || len < iph->ihl*4)
525                 goto out;
526
527         /*
528          * Our transport medium may have padded the buffer out.
529          * Now We trim to the true length of the frame.
530          */
531         if (pskb_trim_rcsum(skb, len))
532                 goto out;
533
534         if (iph->protocol != IPPROTO_UDP)
535                 goto out;
536
537         len -= iph->ihl*4;
538         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
539         ulen = ntohs(uh->len);
540
541         if (ulen != len)
542                 goto out;
543         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
544                 goto out;
545         if (np->local_ip && np->local_ip != iph->daddr)
546                 goto out;
547         if (np->remote_ip && np->remote_ip != iph->saddr)
548                 goto out;
549         if (np->local_port && np->local_port != ntohs(uh->dest))
550                 goto out;
551
552         np->rx_hook(np, ntohs(uh->source),
553                     (char *)(uh+1),
554                     ulen - sizeof(struct udphdr));
555
556         kfree_skb(skb);
557         return 1;
558
559 out:
560         if (atomic_read(&trapped)) {
561                 kfree_skb(skb);
562                 return 1;
563         }
564
565         return 0;
566 }
567
568 void netpoll_print_options(struct netpoll *np)
569 {
570         printk(KERN_INFO "%s: local port %d\n",
571                          np->name, np->local_port);
572         printk(KERN_INFO "%s: local IP %pI4\n",
573                          np->name, &np->local_ip);
574         printk(KERN_INFO "%s: interface %s\n",
575                          np->name, np->dev_name);
576         printk(KERN_INFO "%s: remote port %d\n",
577                          np->name, np->remote_port);
578         printk(KERN_INFO "%s: remote IP %pI4\n",
579                          np->name, &np->remote_ip);
580         printk(KERN_INFO "%s: remote ethernet address %pM\n",
581                          np->name, np->remote_mac);
582 }
583
584 int netpoll_parse_options(struct netpoll *np, char *opt)
585 {
586         char *cur=opt, *delim;
587
588         if (*cur != '@') {
589                 if ((delim = strchr(cur, '@')) == NULL)
590                         goto parse_failed;
591                 *delim = 0;
592                 np->local_port = simple_strtol(cur, NULL, 10);
593                 cur = delim;
594         }
595         cur++;
596
597         if (*cur != '/') {
598                 if ((delim = strchr(cur, '/')) == NULL)
599                         goto parse_failed;
600                 *delim = 0;
601                 np->local_ip = in_aton(cur);
602                 cur = delim;
603         }
604         cur++;
605
606         if (*cur != ',') {
607                 /* parse out dev name */
608                 if ((delim = strchr(cur, ',')) == NULL)
609                         goto parse_failed;
610                 *delim = 0;
611                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
612                 cur = delim;
613         }
614         cur++;
615
616         if (*cur != '@') {
617                 /* dst port */
618                 if ((delim = strchr(cur, '@')) == NULL)
619                         goto parse_failed;
620                 *delim = 0;
621                 np->remote_port = simple_strtol(cur, NULL, 10);
622                 cur = delim;
623         }
624         cur++;
625
626         /* dst ip */
627         if ((delim = strchr(cur, '/')) == NULL)
628                 goto parse_failed;
629         *delim = 0;
630         np->remote_ip = in_aton(cur);
631         cur = delim + 1;
632
633         if (*cur != 0) {
634                 /* MAC address */
635                 if ((delim = strchr(cur, ':')) == NULL)
636                         goto parse_failed;
637                 *delim = 0;
638                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
639                 cur = delim + 1;
640                 if ((delim = strchr(cur, ':')) == NULL)
641                         goto parse_failed;
642                 *delim = 0;
643                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
644                 cur = delim + 1;
645                 if ((delim = strchr(cur, ':')) == NULL)
646                         goto parse_failed;
647                 *delim = 0;
648                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
649                 cur = delim + 1;
650                 if ((delim = strchr(cur, ':')) == NULL)
651                         goto parse_failed;
652                 *delim = 0;
653                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
654                 cur = delim + 1;
655                 if ((delim = strchr(cur, ':')) == NULL)
656                         goto parse_failed;
657                 *delim = 0;
658                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
659                 cur = delim + 1;
660                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
661         }
662
663         netpoll_print_options(np);
664
665         return 0;
666
667  parse_failed:
668         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
669                np->name, cur);
670         return -1;
671 }
672
673 int netpoll_setup(struct netpoll *np)
674 {
675         struct net_device *ndev = NULL;
676         struct in_device *in_dev;
677         struct netpoll_info *npinfo;
678         unsigned long flags;
679         int err;
680
681         if (np->dev_name)
682                 ndev = dev_get_by_name(&init_net, np->dev_name);
683         if (!ndev) {
684                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
685                        np->name, np->dev_name);
686                 return -ENODEV;
687         }
688
689         np->dev = ndev;
690         if (!ndev->npinfo) {
691                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
692                 if (!npinfo) {
693                         err = -ENOMEM;
694                         goto release;
695                 }
696
697                 npinfo->rx_flags = 0;
698                 npinfo->rx_np = NULL;
699
700                 spin_lock_init(&npinfo->rx_lock);
701                 skb_queue_head_init(&npinfo->arp_tx);
702                 skb_queue_head_init(&npinfo->txq);
703                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
704
705                 atomic_set(&npinfo->refcnt, 1);
706         } else {
707                 npinfo = ndev->npinfo;
708                 atomic_inc(&npinfo->refcnt);
709         }
710
711         if (!ndev->netdev_ops->ndo_poll_controller) {
712                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
713                        np->name, np->dev_name);
714                 err = -ENOTSUPP;
715                 goto release;
716         }
717
718         if (!netif_running(ndev)) {
719                 unsigned long atmost, atleast;
720
721                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
722                        np->name, np->dev_name);
723
724                 rtnl_lock();
725                 err = dev_open(ndev);
726                 rtnl_unlock();
727
728                 if (err) {
729                         printk(KERN_ERR "%s: failed to open %s\n",
730                                np->name, ndev->name);
731                         goto release;
732                 }
733
734                 atleast = jiffies + HZ/10;
735                 atmost = jiffies + 4*HZ;
736                 while (!netif_carrier_ok(ndev)) {
737                         if (time_after(jiffies, atmost)) {
738                                 printk(KERN_NOTICE
739                                        "%s: timeout waiting for carrier\n",
740                                        np->name);
741                                 break;
742                         }
743                         cond_resched();
744                 }
745
746                 /* If carrier appears to come up instantly, we don't
747                  * trust it and pause so that we don't pump all our
748                  * queued console messages into the bitbucket.
749                  */
750
751                 if (time_before(jiffies, atleast)) {
752                         printk(KERN_NOTICE "%s: carrier detect appears"
753                                " untrustworthy, waiting 4 seconds\n",
754                                np->name);
755                         msleep(4000);
756                 }
757         }
758
759         if (!np->local_ip) {
760                 rcu_read_lock();
761                 in_dev = __in_dev_get_rcu(ndev);
762
763                 if (!in_dev || !in_dev->ifa_list) {
764                         rcu_read_unlock();
765                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
766                                np->name, np->dev_name);
767                         err = -EDESTADDRREQ;
768                         goto release;
769                 }
770
771                 np->local_ip = in_dev->ifa_list->ifa_local;
772                 rcu_read_unlock();
773                 printk(KERN_INFO "%s: local IP %pI4\n", np->name, &np->local_ip);
774         }
775
776         if (np->rx_hook) {
777                 spin_lock_irqsave(&npinfo->rx_lock, flags);
778                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
779                 npinfo->rx_np = np;
780                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
781         }
782
783         /* fill up the skb queue */
784         refill_skbs();
785
786         /* last thing to do is link it to the net device structure */
787         ndev->npinfo = npinfo;
788
789         /* avoid racing with NAPI reading npinfo */
790         synchronize_rcu();
791
792         return 0;
793
794  release:
795         if (!ndev->npinfo)
796                 kfree(npinfo);
797         np->dev = NULL;
798         dev_put(ndev);
799         return err;
800 }
801
802 static int __init netpoll_init(void)
803 {
804         skb_queue_head_init(&skb_pool);
805         return 0;
806 }
807 core_initcall(netpoll_init);
808
809 void netpoll_cleanup(struct netpoll *np)
810 {
811         struct netpoll_info *npinfo;
812         unsigned long flags;
813
814         if (np->dev) {
815                 npinfo = np->dev->npinfo;
816                 if (npinfo) {
817                         if (npinfo->rx_np == np) {
818                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
819                                 npinfo->rx_np = NULL;
820                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
821                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
822                         }
823
824                         if (atomic_dec_and_test(&npinfo->refcnt)) {
825                                 skb_queue_purge(&npinfo->arp_tx);
826                                 skb_queue_purge(&npinfo->txq);
827                                 cancel_rearming_delayed_work(&npinfo->tx_work);
828
829                                 /* clean after last, unfinished work */
830                                 __skb_queue_purge(&npinfo->txq);
831                                 kfree(npinfo);
832                                 np->dev->npinfo = NULL;
833                         }
834                 }
835
836                 dev_put(np->dev);
837         }
838
839         np->dev = NULL;
840 }
841
842 int netpoll_trap(void)
843 {
844         return atomic_read(&trapped);
845 }
846
847 void netpoll_set_trap(int trap)
848 {
849         if (trap)
850                 atomic_inc(&trapped);
851         else
852                 atomic_dec(&trapped);
853 }
854
855 EXPORT_SYMBOL(netpoll_set_trap);
856 EXPORT_SYMBOL(netpoll_trap);
857 EXPORT_SYMBOL(netpoll_print_options);
858 EXPORT_SYMBOL(netpoll_parse_options);
859 EXPORT_SYMBOL(netpoll_setup);
860 EXPORT_SYMBOL(netpoll_cleanup);
861 EXPORT_SYMBOL(netpoll_send_udp);
862 EXPORT_SYMBOL(netpoll_poll);