[NET] netconsole: Support dynamic reconfiguration using configfs
[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
28 /*
29  * We maintain a small pool of fully-sized skbs, to make sure the
30  * message gets out even in extreme OOM situations.
31  */
32
33 #define MAX_UDP_CHUNK 1460
34 #define MAX_SKBS 32
35 #define MAX_QUEUE_DEPTH (MAX_SKBS / 2)
36
37 static struct sk_buff_head skb_pool;
38
39 static atomic_t trapped;
40
41 #define USEC_PER_POLL   50
42 #define NETPOLL_RX_ENABLED  1
43 #define NETPOLL_RX_DROP     2
44
45 #define MAX_SKB_SIZE \
46                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
47                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
48
49 static void zap_completion_queue(void);
50 static void arp_reply(struct sk_buff *skb);
51
52 static void queue_process(struct work_struct *work)
53 {
54         struct netpoll_info *npinfo =
55                 container_of(work, struct netpoll_info, tx_work.work);
56         struct sk_buff *skb;
57         unsigned long flags;
58
59         while ((skb = skb_dequeue(&npinfo->txq))) {
60                 struct net_device *dev = skb->dev;
61
62                 if (!netif_device_present(dev) || !netif_running(dev)) {
63                         __kfree_skb(skb);
64                         continue;
65                 }
66
67                 local_irq_save(flags);
68                 netif_tx_lock(dev);
69                 if ((netif_queue_stopped(dev) ||
70                      netif_subqueue_stopped(dev, skb->queue_mapping)) ||
71                      dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
72                         skb_queue_head(&npinfo->txq, skb);
73                         netif_tx_unlock(dev);
74                         local_irq_restore(flags);
75
76                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
77                         return;
78                 }
79                 netif_tx_unlock(dev);
80                 local_irq_restore(flags);
81         }
82 }
83
84 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
85                             unsigned short ulen, __be32 saddr, __be32 daddr)
86 {
87         __wsum psum;
88
89         if (uh->check == 0 || skb_csum_unnecessary(skb))
90                 return 0;
91
92         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
93
94         if (skb->ip_summed == CHECKSUM_COMPLETE &&
95             !csum_fold(csum_add(psum, skb->csum)))
96                 return 0;
97
98         skb->csum = psum;
99
100         return __skb_checksum_complete(skb);
101 }
102
103 /*
104  * Check whether delayed processing was scheduled for our NIC. If so,
105  * we attempt to grab the poll lock and use ->poll() to pump the card.
106  * If this fails, either we've recursed in ->poll() or it's already
107  * running on another CPU.
108  *
109  * Note: we don't mask interrupts with this lock because we're using
110  * trylock here and interrupts are already disabled in the softirq
111  * case. Further, we test the poll_owner to avoid recursion on UP
112  * systems where the lock doesn't exist.
113  *
114  * In cases where there is bi-directional communications, reading only
115  * one message at a time can lead to packets being dropped by the
116  * network adapter, forcing superfluous retries and possibly timeouts.
117  * Thus, we set our budget to greater than 1.
118  */
119 static void poll_napi(struct netpoll *np)
120 {
121         struct netpoll_info *npinfo = np->dev->npinfo;
122         struct napi_struct *napi;
123         int budget = 16;
124
125         list_for_each_entry(napi, &np->dev->napi_list, dev_list) {
126                 if (test_bit(NAPI_STATE_SCHED, &napi->state) &&
127                     napi->poll_owner != smp_processor_id() &&
128                     spin_trylock(&napi->poll_lock)) {
129                         npinfo->rx_flags |= NETPOLL_RX_DROP;
130                         atomic_inc(&trapped);
131
132                         napi->poll(napi, budget);
133
134                         atomic_dec(&trapped);
135                         npinfo->rx_flags &= ~NETPOLL_RX_DROP;
136                         spin_unlock(&napi->poll_lock);
137                 }
138         }
139 }
140
141 static void service_arp_queue(struct netpoll_info *npi)
142 {
143         struct sk_buff *skb;
144
145         if (unlikely(!npi))
146                 return;
147
148         skb = skb_dequeue(&npi->arp_tx);
149
150         while (skb != NULL) {
151                 arp_reply(skb);
152                 skb = skb_dequeue(&npi->arp_tx);
153         }
154 }
155
156 void netpoll_poll(struct netpoll *np)
157 {
158         if (!np->dev || !netif_running(np->dev) || !np->dev->poll_controller)
159                 return;
160
161         /* Process pending work on NIC */
162         np->dev->poll_controller(np->dev);
163         if (!list_empty(&np->dev->napi_list))
164                 poll_napi(np);
165
166         service_arp_queue(np->dev->npinfo);
167
168         zap_completion_queue();
169 }
170
171 static void refill_skbs(void)
172 {
173         struct sk_buff *skb;
174         unsigned long flags;
175
176         spin_lock_irqsave(&skb_pool.lock, flags);
177         while (skb_pool.qlen < MAX_SKBS) {
178                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
179                 if (!skb)
180                         break;
181
182                 __skb_queue_tail(&skb_pool, skb);
183         }
184         spin_unlock_irqrestore(&skb_pool.lock, flags);
185 }
186
187 static void zap_completion_queue(void)
188 {
189         unsigned long flags;
190         struct softnet_data *sd = &get_cpu_var(softnet_data);
191
192         if (sd->completion_queue) {
193                 struct sk_buff *clist;
194
195                 local_irq_save(flags);
196                 clist = sd->completion_queue;
197                 sd->completion_queue = NULL;
198                 local_irq_restore(flags);
199
200                 while (clist != NULL) {
201                         struct sk_buff *skb = clist;
202                         clist = clist->next;
203                         if (skb->destructor)
204                                 dev_kfree_skb_any(skb); /* put this one back */
205                         else
206                                 __kfree_skb(skb);
207                 }
208         }
209
210         put_cpu_var(softnet_data);
211 }
212
213 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
214 {
215         int count = 0;
216         struct sk_buff *skb;
217
218         zap_completion_queue();
219         refill_skbs();
220 repeat:
221
222         skb = alloc_skb(len, GFP_ATOMIC);
223         if (!skb)
224                 skb = skb_dequeue(&skb_pool);
225
226         if (!skb) {
227                 if (++count < 10) {
228                         netpoll_poll(np);
229                         goto repeat;
230                 }
231                 return NULL;
232         }
233
234         atomic_set(&skb->users, 1);
235         skb_reserve(skb, reserve);
236         return skb;
237 }
238
239 static int netpoll_owner_active(struct net_device *dev)
240 {
241         struct napi_struct *napi;
242
243         list_for_each_entry(napi, &dev->napi_list, dev_list) {
244                 if (napi->poll_owner == smp_processor_id())
245                         return 1;
246         }
247         return 0;
248 }
249
250 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
251 {
252         int status = NETDEV_TX_BUSY;
253         unsigned long tries;
254         struct net_device *dev = np->dev;
255         struct netpoll_info *npinfo = np->dev->npinfo;
256
257         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
258                 __kfree_skb(skb);
259                 return;
260         }
261
262         /* don't get messages out of order, and no recursion */
263         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
264                 unsigned long flags;
265
266                 local_irq_save(flags);
267                 /* try until next clock tick */
268                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
269                      tries > 0; --tries) {
270                         if (netif_tx_trylock(dev)) {
271                                 if (!netif_queue_stopped(dev) &&
272                                     !netif_subqueue_stopped(dev, skb->queue_mapping))
273                                         status = dev->hard_start_xmit(skb, dev);
274                                 netif_tx_unlock(dev);
275
276                                 if (status == NETDEV_TX_OK)
277                                         break;
278
279                         }
280
281                         /* tickle device maybe there is some cleanup */
282                         netpoll_poll(np);
283
284                         udelay(USEC_PER_POLL);
285                 }
286                 local_irq_restore(flags);
287         }
288
289         if (status != NETDEV_TX_OK) {
290                 skb_queue_tail(&npinfo->txq, skb);
291                 schedule_delayed_work(&npinfo->tx_work,0);
292         }
293 }
294
295 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
296 {
297         int total_len, eth_len, ip_len, udp_len;
298         struct sk_buff *skb;
299         struct udphdr *udph;
300         struct iphdr *iph;
301         struct ethhdr *eth;
302
303         udp_len = len + sizeof(*udph);
304         ip_len = eth_len = udp_len + sizeof(*iph);
305         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
306
307         skb = find_skb(np, total_len, total_len - len);
308         if (!skb)
309                 return;
310
311         skb_copy_to_linear_data(skb, msg, len);
312         skb->len += len;
313
314         skb_push(skb, sizeof(*udph));
315         skb_reset_transport_header(skb);
316         udph = udp_hdr(skb);
317         udph->source = htons(np->local_port);
318         udph->dest = htons(np->remote_port);
319         udph->len = htons(udp_len);
320         udph->check = 0;
321         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
322                                         htonl(np->remote_ip),
323                                         udp_len, IPPROTO_UDP,
324                                         csum_partial((unsigned char *)udph, udp_len, 0));
325         if (udph->check == 0)
326                 udph->check = CSUM_MANGLED_0;
327
328         skb_push(skb, sizeof(*iph));
329         skb_reset_network_header(skb);
330         iph = ip_hdr(skb);
331
332         /* iph->version = 4; iph->ihl = 5; */
333         put_unaligned(0x45, (unsigned char *)iph);
334         iph->tos      = 0;
335         put_unaligned(htons(ip_len), &(iph->tot_len));
336         iph->id       = 0;
337         iph->frag_off = 0;
338         iph->ttl      = 64;
339         iph->protocol = IPPROTO_UDP;
340         iph->check    = 0;
341         put_unaligned(htonl(np->local_ip), &(iph->saddr));
342         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
343         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
344
345         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
346         skb_reset_mac_header(skb);
347         skb->protocol = eth->h_proto = htons(ETH_P_IP);
348         memcpy(eth->h_source, np->local_mac, 6);
349         memcpy(eth->h_dest, np->remote_mac, 6);
350
351         skb->dev = np->dev;
352
353         netpoll_send_skb(np, skb);
354 }
355
356 static void arp_reply(struct sk_buff *skb)
357 {
358         struct netpoll_info *npinfo = skb->dev->npinfo;
359         struct arphdr *arp;
360         unsigned char *arp_ptr;
361         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
362         __be32 sip, tip;
363         unsigned char *sha;
364         struct sk_buff *send_skb;
365         struct netpoll *np = NULL;
366
367         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
368                 np = npinfo->rx_np;
369         if (!np)
370                 return;
371
372         /* No arp on this interface */
373         if (skb->dev->flags & IFF_NOARP)
374                 return;
375
376         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
377                                  (2 * skb->dev->addr_len) +
378                                  (2 * sizeof(u32)))))
379                 return;
380
381         skb_reset_network_header(skb);
382         skb_reset_transport_header(skb);
383         arp = arp_hdr(skb);
384
385         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
386              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
387             arp->ar_pro != htons(ETH_P_IP) ||
388             arp->ar_op != htons(ARPOP_REQUEST))
389                 return;
390
391         arp_ptr = (unsigned char *)(arp+1);
392         /* save the location of the src hw addr */
393         sha = arp_ptr;
394         arp_ptr += skb->dev->addr_len;
395         memcpy(&sip, arp_ptr, 4);
396         arp_ptr += 4;
397         /* if we actually cared about dst hw addr, it would get copied here */
398         arp_ptr += skb->dev->addr_len;
399         memcpy(&tip, arp_ptr, 4);
400
401         /* Should we ignore arp? */
402         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
403                 return;
404
405         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
406         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
407                             LL_RESERVED_SPACE(np->dev));
408
409         if (!send_skb)
410                 return;
411
412         skb_reset_network_header(send_skb);
413         arp = (struct arphdr *) skb_put(send_skb, size);
414         send_skb->dev = skb->dev;
415         send_skb->protocol = htons(ETH_P_ARP);
416
417         /* Fill the device header for the ARP frame */
418
419         if (np->dev->hard_header &&
420             np->dev->hard_header(send_skb, skb->dev, ptype,
421                                  sha, np->local_mac,
422                                  send_skb->len) < 0) {
423                 kfree_skb(send_skb);
424                 return;
425         }
426
427         /*
428          * Fill out the arp protocol part.
429          *
430          * we only support ethernet device type,
431          * which (according to RFC 1390) should always equal 1 (Ethernet).
432          */
433
434         arp->ar_hrd = htons(np->dev->type);
435         arp->ar_pro = htons(ETH_P_IP);
436         arp->ar_hln = np->dev->addr_len;
437         arp->ar_pln = 4;
438         arp->ar_op = htons(type);
439
440         arp_ptr=(unsigned char *)(arp + 1);
441         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
442         arp_ptr += np->dev->addr_len;
443         memcpy(arp_ptr, &tip, 4);
444         arp_ptr += 4;
445         memcpy(arp_ptr, sha, np->dev->addr_len);
446         arp_ptr += np->dev->addr_len;
447         memcpy(arp_ptr, &sip, 4);
448
449         netpoll_send_skb(np, send_skb);
450 }
451
452 int __netpoll_rx(struct sk_buff *skb)
453 {
454         int proto, len, ulen;
455         struct iphdr *iph;
456         struct udphdr *uh;
457         struct netpoll_info *npi = skb->dev->npinfo;
458         struct netpoll *np = npi->rx_np;
459
460         if (!np)
461                 goto out;
462         if (skb->dev->type != ARPHRD_ETHER)
463                 goto out;
464
465         /* check if netpoll clients need ARP */
466         if (skb->protocol == htons(ETH_P_ARP) &&
467             atomic_read(&trapped)) {
468                 skb_queue_tail(&npi->arp_tx, skb);
469                 return 1;
470         }
471
472         proto = ntohs(eth_hdr(skb)->h_proto);
473         if (proto != ETH_P_IP)
474                 goto out;
475         if (skb->pkt_type == PACKET_OTHERHOST)
476                 goto out;
477         if (skb_shared(skb))
478                 goto out;
479
480         iph = (struct iphdr *)skb->data;
481         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
482                 goto out;
483         if (iph->ihl < 5 || iph->version != 4)
484                 goto out;
485         if (!pskb_may_pull(skb, iph->ihl*4))
486                 goto out;
487         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
488                 goto out;
489
490         len = ntohs(iph->tot_len);
491         if (skb->len < len || len < iph->ihl*4)
492                 goto out;
493
494         /*
495          * Our transport medium may have padded the buffer out.
496          * Now We trim to the true length of the frame.
497          */
498         if (pskb_trim_rcsum(skb, len))
499                 goto out;
500
501         if (iph->protocol != IPPROTO_UDP)
502                 goto out;
503
504         len -= iph->ihl*4;
505         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
506         ulen = ntohs(uh->len);
507
508         if (ulen != len)
509                 goto out;
510         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
511                 goto out;
512         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
513                 goto out;
514         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
515                 goto out;
516         if (np->local_port && np->local_port != ntohs(uh->dest))
517                 goto out;
518
519         np->rx_hook(np, ntohs(uh->source),
520                     (char *)(uh+1),
521                     ulen - sizeof(struct udphdr));
522
523         kfree_skb(skb);
524         return 1;
525
526 out:
527         if (atomic_read(&trapped)) {
528                 kfree_skb(skb);
529                 return 1;
530         }
531
532         return 0;
533 }
534
535 void netpoll_print_options(struct netpoll *np)
536 {
537         printk(KERN_INFO "%s: local port %d\n",
538                          np->name, np->local_port);
539         printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
540                          np->name, HIPQUAD(np->local_ip));
541         printk(KERN_INFO "%s: interface %s\n",
542                          np->name, np->dev_name);
543         printk(KERN_INFO "%s: remote port %d\n",
544                          np->name, np->remote_port);
545         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
546                          np->name, HIPQUAD(np->remote_ip));
547         printk(KERN_INFO "%s: remote ethernet address "
548                          "%02x:%02x:%02x:%02x:%02x:%02x\n",
549                          np->name,
550                          np->remote_mac[0],
551                          np->remote_mac[1],
552                          np->remote_mac[2],
553                          np->remote_mac[3],
554                          np->remote_mac[4],
555                          np->remote_mac[5]);
556 }
557
558 int netpoll_parse_options(struct netpoll *np, char *opt)
559 {
560         char *cur=opt, *delim;
561
562         if (*cur != '@') {
563                 if ((delim = strchr(cur, '@')) == NULL)
564                         goto parse_failed;
565                 *delim = 0;
566                 np->local_port = simple_strtol(cur, NULL, 10);
567                 cur = delim;
568         }
569         cur++;
570
571         if (*cur != '/') {
572                 if ((delim = strchr(cur, '/')) == NULL)
573                         goto parse_failed;
574                 *delim = 0;
575                 np->local_ip = ntohl(in_aton(cur));
576                 cur = delim;
577         }
578         cur++;
579
580         if (*cur != ',') {
581                 /* parse out dev name */
582                 if ((delim = strchr(cur, ',')) == NULL)
583                         goto parse_failed;
584                 *delim = 0;
585                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
586                 cur = delim;
587         }
588         cur++;
589
590         if (*cur != '@') {
591                 /* dst port */
592                 if ((delim = strchr(cur, '@')) == NULL)
593                         goto parse_failed;
594                 *delim = 0;
595                 np->remote_port = simple_strtol(cur, NULL, 10);
596                 cur = delim;
597         }
598         cur++;
599
600         /* dst ip */
601         if ((delim = strchr(cur, '/')) == NULL)
602                 goto parse_failed;
603         *delim = 0;
604         np->remote_ip = ntohl(in_aton(cur));
605         cur = delim + 1;
606
607         if (*cur != 0) {
608                 /* MAC address */
609                 if ((delim = strchr(cur, ':')) == NULL)
610                         goto parse_failed;
611                 *delim = 0;
612                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
613                 cur = delim + 1;
614                 if ((delim = strchr(cur, ':')) == NULL)
615                         goto parse_failed;
616                 *delim = 0;
617                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
618                 cur = delim + 1;
619                 if ((delim = strchr(cur, ':')) == NULL)
620                         goto parse_failed;
621                 *delim = 0;
622                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
623                 cur = delim + 1;
624                 if ((delim = strchr(cur, ':')) == NULL)
625                         goto parse_failed;
626                 *delim = 0;
627                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
628                 cur = delim + 1;
629                 if ((delim = strchr(cur, ':')) == NULL)
630                         goto parse_failed;
631                 *delim = 0;
632                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
633                 cur = delim + 1;
634                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
635         }
636
637         netpoll_print_options(np);
638
639         return 0;
640
641  parse_failed:
642         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
643                np->name, cur);
644         return -1;
645 }
646
647 int netpoll_setup(struct netpoll *np)
648 {
649         struct net_device *ndev = NULL;
650         struct in_device *in_dev;
651         struct netpoll_info *npinfo;
652         unsigned long flags;
653         int err;
654
655         if (np->dev_name)
656                 ndev = dev_get_by_name(np->dev_name);
657         if (!ndev) {
658                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
659                        np->name, np->dev_name);
660                 return -ENODEV;
661         }
662
663         np->dev = ndev;
664         if (!ndev->npinfo) {
665                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
666                 if (!npinfo) {
667                         err = -ENOMEM;
668                         goto release;
669                 }
670
671                 npinfo->rx_flags = 0;
672                 npinfo->rx_np = NULL;
673
674                 spin_lock_init(&npinfo->rx_lock);
675                 skb_queue_head_init(&npinfo->arp_tx);
676                 skb_queue_head_init(&npinfo->txq);
677                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
678
679                 atomic_set(&npinfo->refcnt, 1);
680         } else {
681                 npinfo = ndev->npinfo;
682                 atomic_inc(&npinfo->refcnt);
683         }
684
685         if (!ndev->poll_controller) {
686                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
687                        np->name, np->dev_name);
688                 err = -ENOTSUPP;
689                 goto release;
690         }
691
692         if (!netif_running(ndev)) {
693                 unsigned long atmost, atleast;
694
695                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
696                        np->name, np->dev_name);
697
698                 rtnl_lock();
699                 err = dev_open(ndev);
700                 rtnl_unlock();
701
702                 if (err) {
703                         printk(KERN_ERR "%s: failed to open %s\n",
704                                np->name, ndev->name);
705                         goto release;
706                 }
707
708                 atleast = jiffies + HZ/10;
709                 atmost = jiffies + 4*HZ;
710                 while (!netif_carrier_ok(ndev)) {
711                         if (time_after(jiffies, atmost)) {
712                                 printk(KERN_NOTICE
713                                        "%s: timeout waiting for carrier\n",
714                                        np->name);
715                                 break;
716                         }
717                         cond_resched();
718                 }
719
720                 /* If carrier appears to come up instantly, we don't
721                  * trust it and pause so that we don't pump all our
722                  * queued console messages into the bitbucket.
723                  */
724
725                 if (time_before(jiffies, atleast)) {
726                         printk(KERN_NOTICE "%s: carrier detect appears"
727                                " untrustworthy, waiting 4 seconds\n",
728                                np->name);
729                         msleep(4000);
730                 }
731         }
732
733         if (is_zero_ether_addr(np->local_mac) && ndev->dev_addr)
734                 memcpy(np->local_mac, ndev->dev_addr, 6);
735
736         if (!np->local_ip) {
737                 rcu_read_lock();
738                 in_dev = __in_dev_get_rcu(ndev);
739
740                 if (!in_dev || !in_dev->ifa_list) {
741                         rcu_read_unlock();
742                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
743                                np->name, np->dev_name);
744                         err = -EDESTADDRREQ;
745                         goto release;
746                 }
747
748                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
749                 rcu_read_unlock();
750                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
751                        np->name, HIPQUAD(np->local_ip));
752         }
753
754         if (np->rx_hook) {
755                 spin_lock_irqsave(&npinfo->rx_lock, flags);
756                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
757                 npinfo->rx_np = np;
758                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
759         }
760
761         /* fill up the skb queue */
762         refill_skbs();
763
764         /* last thing to do is link it to the net device structure */
765         ndev->npinfo = npinfo;
766
767         /* avoid racing with NAPI reading npinfo */
768         synchronize_rcu();
769
770         return 0;
771
772  release:
773         if (!ndev->npinfo)
774                 kfree(npinfo);
775         np->dev = NULL;
776         dev_put(ndev);
777         return err;
778 }
779
780 static int __init netpoll_init(void)
781 {
782         skb_queue_head_init(&skb_pool);
783         return 0;
784 }
785 core_initcall(netpoll_init);
786
787 void netpoll_cleanup(struct netpoll *np)
788 {
789         struct netpoll_info *npinfo;
790         unsigned long flags;
791
792         if (np->dev) {
793                 npinfo = np->dev->npinfo;
794                 if (npinfo) {
795                         if (npinfo->rx_np == np) {
796                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
797                                 npinfo->rx_np = NULL;
798                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
799                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
800                         }
801
802                         if (atomic_dec_and_test(&npinfo->refcnt)) {
803                                 skb_queue_purge(&npinfo->arp_tx);
804                                 skb_queue_purge(&npinfo->txq);
805                                 cancel_rearming_delayed_work(&npinfo->tx_work);
806
807                                 /* clean after last, unfinished work */
808                                 if (!skb_queue_empty(&npinfo->txq)) {
809                                         struct sk_buff *skb;
810                                         skb = __skb_dequeue(&npinfo->txq);
811                                         kfree_skb(skb);
812                                 }
813                                 kfree(npinfo);
814                                 np->dev->npinfo = NULL;
815                         }
816                 }
817
818                 dev_put(np->dev);
819         }
820
821         np->dev = NULL;
822 }
823
824 int netpoll_trap(void)
825 {
826         return atomic_read(&trapped);
827 }
828
829 void netpoll_set_trap(int trap)
830 {
831         if (trap)
832                 atomic_inc(&trapped);
833         else
834                 atomic_dec(&trapped);
835 }
836
837 EXPORT_SYMBOL(netpoll_set_trap);
838 EXPORT_SYMBOL(netpoll_trap);
839 EXPORT_SYMBOL(netpoll_print_options);
840 EXPORT_SYMBOL(netpoll_parse_options);
841 EXPORT_SYMBOL(netpoll_setup);
842 EXPORT_SYMBOL(netpoll_cleanup);
843 EXPORT_SYMBOL(netpoll_send_udp);
844 EXPORT_SYMBOL(netpoll_poll);