[IPV4] net/core: Use ipv4_is_<type>
[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
43 #define MAX_SKB_SIZE \
44                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
45                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
46
47 static void zap_completion_queue(void);
48 static void arp_reply(struct sk_buff *skb);
49
50 static void queue_process(struct work_struct *work)
51 {
52         struct netpoll_info *npinfo =
53                 container_of(work, struct netpoll_info, tx_work.work);
54         struct sk_buff *skb;
55         unsigned long flags;
56
57         while ((skb = skb_dequeue(&npinfo->txq))) {
58                 struct net_device *dev = skb->dev;
59
60                 if (!netif_device_present(dev) || !netif_running(dev)) {
61                         __kfree_skb(skb);
62                         continue;
63                 }
64
65                 local_irq_save(flags);
66                 netif_tx_lock(dev);
67                 if ((netif_queue_stopped(dev) ||
68                      netif_subqueue_stopped(dev, skb)) ||
69                      dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
70                         skb_queue_head(&npinfo->txq, skb);
71                         netif_tx_unlock(dev);
72                         local_irq_restore(flags);
73
74                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
75                         return;
76                 }
77                 netif_tx_unlock(dev);
78                 local_irq_restore(flags);
79         }
80 }
81
82 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
83                             unsigned short ulen, __be32 saddr, __be32 daddr)
84 {
85         __wsum psum;
86
87         if (uh->check == 0 || skb_csum_unnecessary(skb))
88                 return 0;
89
90         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
91
92         if (skb->ip_summed == CHECKSUM_COMPLETE &&
93             !csum_fold(csum_add(psum, skb->csum)))
94                 return 0;
95
96         skb->csum = psum;
97
98         return __skb_checksum_complete(skb);
99 }
100
101 /*
102  * Check whether delayed processing was scheduled for our NIC. If so,
103  * we attempt to grab the poll lock and use ->poll() to pump the card.
104  * If this fails, either we've recursed in ->poll() or it's already
105  * running on another CPU.
106  *
107  * Note: we don't mask interrupts with this lock because we're using
108  * trylock here and interrupts are already disabled in the softirq
109  * case. Further, we test the poll_owner to avoid recursion on UP
110  * systems where the lock doesn't exist.
111  *
112  * In cases where there is bi-directional communications, reading only
113  * one message at a time can lead to packets being dropped by the
114  * network adapter, forcing superfluous retries and possibly timeouts.
115  * Thus, we set our budget to greater than 1.
116  */
117 static int poll_one_napi(struct netpoll_info *npinfo,
118                          struct napi_struct *napi, int budget)
119 {
120         int work;
121
122         /* net_rx_action's ->poll() invocations and our's are
123          * synchronized by this test which is only made while
124          * holding the napi->poll_lock.
125          */
126         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
127                 return budget;
128
129         atomic_inc(&trapped);
130
131         work = napi->poll(napi, budget);
132
133         atomic_dec(&trapped);
134
135         return budget - work;
136 }
137
138 static void poll_napi(struct net_device *dev)
139 {
140         struct napi_struct *napi;
141         int budget = 16;
142
143         list_for_each_entry(napi, &dev->napi_list, dev_list) {
144                 if (napi->poll_owner != smp_processor_id() &&
145                     spin_trylock(&napi->poll_lock)) {
146                         budget = poll_one_napi(dev->npinfo, napi, budget);
147                         spin_unlock(&napi->poll_lock);
148
149                         if (!budget)
150                                 break;
151                 }
152         }
153 }
154
155 static void service_arp_queue(struct netpoll_info *npi)
156 {
157         if (npi) {
158                 struct sk_buff *skb;
159
160                 while ((skb = skb_dequeue(&npi->arp_tx)))
161                         arp_reply(skb);
162         }
163 }
164
165 void netpoll_poll(struct netpoll *np)
166 {
167         struct net_device *dev = np->dev;
168
169         if (!dev || !netif_running(dev) || !dev->poll_controller)
170                 return;
171
172         /* Process pending work on NIC */
173         dev->poll_controller(dev);
174
175         poll_napi(dev);
176
177         service_arp_queue(dev->npinfo);
178
179         zap_completion_queue();
180 }
181
182 static void refill_skbs(void)
183 {
184         struct sk_buff *skb;
185         unsigned long flags;
186
187         spin_lock_irqsave(&skb_pool.lock, flags);
188         while (skb_pool.qlen < MAX_SKBS) {
189                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
190                 if (!skb)
191                         break;
192
193                 __skb_queue_tail(&skb_pool, skb);
194         }
195         spin_unlock_irqrestore(&skb_pool.lock, flags);
196 }
197
198 static void zap_completion_queue(void)
199 {
200         unsigned long flags;
201         struct softnet_data *sd = &get_cpu_var(softnet_data);
202
203         if (sd->completion_queue) {
204                 struct sk_buff *clist;
205
206                 local_irq_save(flags);
207                 clist = sd->completion_queue;
208                 sd->completion_queue = NULL;
209                 local_irq_restore(flags);
210
211                 while (clist != NULL) {
212                         struct sk_buff *skb = clist;
213                         clist = clist->next;
214                         if (skb->destructor)
215                                 dev_kfree_skb_any(skb); /* put this one back */
216                         else
217                                 __kfree_skb(skb);
218                 }
219         }
220
221         put_cpu_var(softnet_data);
222 }
223
224 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
225 {
226         int count = 0;
227         struct sk_buff *skb;
228
229         zap_completion_queue();
230         refill_skbs();
231 repeat:
232
233         skb = alloc_skb(len, GFP_ATOMIC);
234         if (!skb)
235                 skb = skb_dequeue(&skb_pool);
236
237         if (!skb) {
238                 if (++count < 10) {
239                         netpoll_poll(np);
240                         goto repeat;
241                 }
242                 return NULL;
243         }
244
245         atomic_set(&skb->users, 1);
246         skb_reserve(skb, reserve);
247         return skb;
248 }
249
250 static int netpoll_owner_active(struct net_device *dev)
251 {
252         struct napi_struct *napi;
253
254         list_for_each_entry(napi, &dev->napi_list, dev_list) {
255                 if (napi->poll_owner == smp_processor_id())
256                         return 1;
257         }
258         return 0;
259 }
260
261 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
262 {
263         int status = NETDEV_TX_BUSY;
264         unsigned long tries;
265         struct net_device *dev = np->dev;
266         struct netpoll_info *npinfo = np->dev->npinfo;
267
268         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
269                 __kfree_skb(skb);
270                 return;
271         }
272
273         /* don't get messages out of order, and no recursion */
274         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
275                 unsigned long flags;
276
277                 local_irq_save(flags);
278                 /* try until next clock tick */
279                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
280                      tries > 0; --tries) {
281                         if (netif_tx_trylock(dev)) {
282                                 if (!netif_queue_stopped(dev) &&
283                                     !netif_subqueue_stopped(dev, skb))
284                                         status = dev->hard_start_xmit(skb, dev);
285                                 netif_tx_unlock(dev);
286
287                                 if (status == NETDEV_TX_OK)
288                                         break;
289
290                         }
291
292                         /* tickle device maybe there is some cleanup */
293                         netpoll_poll(np);
294
295                         udelay(USEC_PER_POLL);
296                 }
297                 local_irq_restore(flags);
298         }
299
300         if (status != NETDEV_TX_OK) {
301                 skb_queue_tail(&npinfo->txq, skb);
302                 schedule_delayed_work(&npinfo->tx_work,0);
303         }
304 }
305
306 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
307 {
308         int total_len, eth_len, ip_len, udp_len;
309         struct sk_buff *skb;
310         struct udphdr *udph;
311         struct iphdr *iph;
312         struct ethhdr *eth;
313
314         udp_len = len + sizeof(*udph);
315         ip_len = eth_len = udp_len + sizeof(*iph);
316         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
317
318         skb = find_skb(np, total_len, total_len - len);
319         if (!skb)
320                 return;
321
322         skb_copy_to_linear_data(skb, msg, len);
323         skb->len += len;
324
325         skb_push(skb, sizeof(*udph));
326         skb_reset_transport_header(skb);
327         udph = udp_hdr(skb);
328         udph->source = htons(np->local_port);
329         udph->dest = htons(np->remote_port);
330         udph->len = htons(udp_len);
331         udph->check = 0;
332         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
333                                         htonl(np->remote_ip),
334                                         udp_len, IPPROTO_UDP,
335                                         csum_partial((unsigned char *)udph, udp_len, 0));
336         if (udph->check == 0)
337                 udph->check = CSUM_MANGLED_0;
338
339         skb_push(skb, sizeof(*iph));
340         skb_reset_network_header(skb);
341         iph = ip_hdr(skb);
342
343         /* iph->version = 4; iph->ihl = 5; */
344         put_unaligned(0x45, (unsigned char *)iph);
345         iph->tos      = 0;
346         put_unaligned(htons(ip_len), &(iph->tot_len));
347         iph->id       = 0;
348         iph->frag_off = 0;
349         iph->ttl      = 64;
350         iph->protocol = IPPROTO_UDP;
351         iph->check    = 0;
352         put_unaligned(htonl(np->local_ip), &(iph->saddr));
353         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
354         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
355
356         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
357         skb_reset_mac_header(skb);
358         skb->protocol = eth->h_proto = htons(ETH_P_IP);
359         memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
360         memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
361
362         skb->dev = np->dev;
363
364         netpoll_send_skb(np, skb);
365 }
366
367 static void arp_reply(struct sk_buff *skb)
368 {
369         struct netpoll_info *npinfo = skb->dev->npinfo;
370         struct arphdr *arp;
371         unsigned char *arp_ptr;
372         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
373         __be32 sip, tip;
374         unsigned char *sha;
375         struct sk_buff *send_skb;
376         struct netpoll *np = NULL;
377
378         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
379                 np = npinfo->rx_np;
380         if (!np)
381                 return;
382
383         /* No arp on this interface */
384         if (skb->dev->flags & IFF_NOARP)
385                 return;
386
387         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
388                                  (2 * skb->dev->addr_len) +
389                                  (2 * sizeof(u32)))))
390                 return;
391
392         skb_reset_network_header(skb);
393         skb_reset_transport_header(skb);
394         arp = arp_hdr(skb);
395
396         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
397              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
398             arp->ar_pro != htons(ETH_P_IP) ||
399             arp->ar_op != htons(ARPOP_REQUEST))
400                 return;
401
402         arp_ptr = (unsigned char *)(arp+1);
403         /* save the location of the src hw addr */
404         sha = arp_ptr;
405         arp_ptr += skb->dev->addr_len;
406         memcpy(&sip, arp_ptr, 4);
407         arp_ptr += 4;
408         /* if we actually cared about dst hw addr, it would get copied here */
409         arp_ptr += skb->dev->addr_len;
410         memcpy(&tip, arp_ptr, 4);
411
412         /* Should we ignore arp? */
413         if (tip != htonl(np->local_ip) ||
414             ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
415                 return;
416
417         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
418         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
419                             LL_RESERVED_SPACE(np->dev));
420
421         if (!send_skb)
422                 return;
423
424         skb_reset_network_header(send_skb);
425         arp = (struct arphdr *) skb_put(send_skb, size);
426         send_skb->dev = skb->dev;
427         send_skb->protocol = htons(ETH_P_ARP);
428
429         /* Fill the device header for the ARP frame */
430         if (dev_hard_header(send_skb, skb->dev, ptype,
431                             sha, np->dev->dev_addr,
432                             send_skb->len) < 0) {
433                 kfree_skb(send_skb);
434                 return;
435         }
436
437         /*
438          * Fill out the arp protocol part.
439          *
440          * we only support ethernet device type,
441          * which (according to RFC 1390) should always equal 1 (Ethernet).
442          */
443
444         arp->ar_hrd = htons(np->dev->type);
445         arp->ar_pro = htons(ETH_P_IP);
446         arp->ar_hln = np->dev->addr_len;
447         arp->ar_pln = 4;
448         arp->ar_op = htons(type);
449
450         arp_ptr=(unsigned char *)(arp + 1);
451         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
452         arp_ptr += np->dev->addr_len;
453         memcpy(arp_ptr, &tip, 4);
454         arp_ptr += 4;
455         memcpy(arp_ptr, sha, np->dev->addr_len);
456         arp_ptr += np->dev->addr_len;
457         memcpy(arp_ptr, &sip, 4);
458
459         netpoll_send_skb(np, send_skb);
460 }
461
462 int __netpoll_rx(struct sk_buff *skb)
463 {
464         int proto, len, ulen;
465         struct iphdr *iph;
466         struct udphdr *uh;
467         struct netpoll_info *npi = skb->dev->npinfo;
468         struct netpoll *np = npi->rx_np;
469
470         if (!np)
471                 goto out;
472         if (skb->dev->type != ARPHRD_ETHER)
473                 goto out;
474
475         /* if receive ARP during middle of NAPI poll, then queue */
476         if (skb->protocol == htons(ETH_P_ARP) &&
477             atomic_read(&trapped)) {
478                 skb_queue_tail(&npi->arp_tx, skb);
479                 return 1;
480         }
481
482         proto = ntohs(eth_hdr(skb)->h_proto);
483         if (proto != ETH_P_IP)
484                 goto out;
485         if (skb->pkt_type == PACKET_OTHERHOST)
486                 goto out;
487         if (skb_shared(skb))
488                 goto out;
489
490         iph = (struct iphdr *)skb->data;
491         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
492                 goto out;
493         if (iph->ihl < 5 || iph->version != 4)
494                 goto out;
495         if (!pskb_may_pull(skb, iph->ihl*4))
496                 goto out;
497         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
498                 goto out;
499
500         len = ntohs(iph->tot_len);
501         if (skb->len < len || len < iph->ihl*4)
502                 goto out;
503
504         /*
505          * Our transport medium may have padded the buffer out.
506          * Now We trim to the true length of the frame.
507          */
508         if (pskb_trim_rcsum(skb, len))
509                 goto out;
510
511         if (iph->protocol != IPPROTO_UDP)
512                 goto out;
513
514         len -= iph->ihl*4;
515         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
516         ulen = ntohs(uh->len);
517
518         if (ulen != len)
519                 goto out;
520         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
521                 goto out;
522         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
523                 goto out;
524         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
525                 goto out;
526         if (np->local_port && np->local_port != ntohs(uh->dest))
527                 goto out;
528
529         np->rx_hook(np, ntohs(uh->source),
530                     (char *)(uh+1),
531                     ulen - sizeof(struct udphdr));
532
533         kfree_skb(skb);
534         return 1;
535
536 out:
537         /* If packet received while already in poll then just
538          * silently drop.
539          */
540         if (atomic_read(&trapped)) {
541                 kfree_skb(skb);
542                 return 1;
543         }
544
545         return 0;
546 }
547
548 void netpoll_print_options(struct netpoll *np)
549 {
550         DECLARE_MAC_BUF(mac);
551         printk(KERN_INFO "%s: local port %d\n",
552                          np->name, np->local_port);
553         printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
554                          np->name, HIPQUAD(np->local_ip));
555         printk(KERN_INFO "%s: interface %s\n",
556                          np->name, np->dev_name);
557         printk(KERN_INFO "%s: remote port %d\n",
558                          np->name, np->remote_port);
559         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
560                          np->name, HIPQUAD(np->remote_ip));
561         printk(KERN_INFO "%s: remote ethernet address %s\n",
562                          np->name, print_mac(mac, np->remote_mac));
563 }
564
565 int netpoll_parse_options(struct netpoll *np, char *opt)
566 {
567         char *cur=opt, *delim;
568
569         if (*cur != '@') {
570                 if ((delim = strchr(cur, '@')) == NULL)
571                         goto parse_failed;
572                 *delim = 0;
573                 np->local_port = simple_strtol(cur, NULL, 10);
574                 cur = delim;
575         }
576         cur++;
577
578         if (*cur != '/') {
579                 if ((delim = strchr(cur, '/')) == NULL)
580                         goto parse_failed;
581                 *delim = 0;
582                 np->local_ip = ntohl(in_aton(cur));
583                 cur = delim;
584         }
585         cur++;
586
587         if (*cur != ',') {
588                 /* parse out dev name */
589                 if ((delim = strchr(cur, ',')) == NULL)
590                         goto parse_failed;
591                 *delim = 0;
592                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
593                 cur = delim;
594         }
595         cur++;
596
597         if (*cur != '@') {
598                 /* dst port */
599                 if ((delim = strchr(cur, '@')) == NULL)
600                         goto parse_failed;
601                 *delim = 0;
602                 np->remote_port = simple_strtol(cur, NULL, 10);
603                 cur = delim;
604         }
605         cur++;
606
607         /* dst ip */
608         if ((delim = strchr(cur, '/')) == NULL)
609                 goto parse_failed;
610         *delim = 0;
611         np->remote_ip = ntohl(in_aton(cur));
612         cur = delim + 1;
613
614         if (*cur != 0) {
615                 /* MAC address */
616                 if ((delim = strchr(cur, ':')) == NULL)
617                         goto parse_failed;
618                 *delim = 0;
619                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
620                 cur = delim + 1;
621                 if ((delim = strchr(cur, ':')) == NULL)
622                         goto parse_failed;
623                 *delim = 0;
624                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
625                 cur = delim + 1;
626                 if ((delim = strchr(cur, ':')) == NULL)
627                         goto parse_failed;
628                 *delim = 0;
629                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
630                 cur = delim + 1;
631                 if ((delim = strchr(cur, ':')) == NULL)
632                         goto parse_failed;
633                 *delim = 0;
634                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
635                 cur = delim + 1;
636                 if ((delim = strchr(cur, ':')) == NULL)
637                         goto parse_failed;
638                 *delim = 0;
639                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
640                 cur = delim + 1;
641                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
642         }
643
644         netpoll_print_options(np);
645
646         return 0;
647
648  parse_failed:
649         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
650                np->name, cur);
651         return -1;
652 }
653
654 int netpoll_setup(struct netpoll *np)
655 {
656         struct net_device *ndev = NULL;
657         struct in_device *in_dev;
658         struct netpoll_info *npinfo;
659         unsigned long flags;
660         int err;
661
662         if (np->dev_name)
663                 ndev = dev_get_by_name(&init_net, np->dev_name);
664         if (!ndev) {
665                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
666                        np->name, np->dev_name);
667                 return -ENODEV;
668         }
669
670         np->dev = ndev;
671         if (!ndev->npinfo) {
672                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
673                 if (!npinfo) {
674                         err = -ENOMEM;
675                         goto release;
676                 }
677
678                 npinfo->rx_np = NULL;
679
680                 spin_lock_init(&npinfo->rx_lock);
681                 skb_queue_head_init(&npinfo->arp_tx);
682                 skb_queue_head_init(&npinfo->txq);
683                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
684
685                 atomic_set(&npinfo->refcnt, 1);
686         } else {
687                 npinfo = ndev->npinfo;
688                 atomic_inc(&npinfo->refcnt);
689         }
690
691         if (!ndev->poll_controller) {
692                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
693                        np->name, np->dev_name);
694                 err = -ENOTSUPP;
695                 goto release;
696         }
697
698         if (!netif_running(ndev)) {
699                 unsigned long atmost, atleast;
700
701                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
702                        np->name, np->dev_name);
703
704                 rtnl_lock();
705                 err = dev_open(ndev);
706                 rtnl_unlock();
707
708                 if (err) {
709                         printk(KERN_ERR "%s: failed to open %s\n",
710                                np->name, ndev->name);
711                         goto release;
712                 }
713
714                 atleast = jiffies + HZ/10;
715                 atmost = jiffies + 4*HZ;
716                 while (!netif_carrier_ok(ndev)) {
717                         if (time_after(jiffies, atmost)) {
718                                 printk(KERN_NOTICE
719                                        "%s: timeout waiting for carrier\n",
720                                        np->name);
721                                 break;
722                         }
723                         cond_resched();
724                 }
725
726                 /* If carrier appears to come up instantly, we don't
727                  * trust it and pause so that we don't pump all our
728                  * queued console messages into the bitbucket.
729                  */
730
731                 if (time_before(jiffies, atleast)) {
732                         printk(KERN_NOTICE "%s: carrier detect appears"
733                                " untrustworthy, waiting 4 seconds\n",
734                                np->name);
735                         msleep(4000);
736                 }
737         }
738
739         if (!np->local_ip) {
740                 rcu_read_lock();
741                 in_dev = __in_dev_get_rcu(ndev);
742
743                 if (!in_dev || !in_dev->ifa_list) {
744                         rcu_read_unlock();
745                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
746                                np->name, np->dev_name);
747                         err = -EDESTADDRREQ;
748                         goto release;
749                 }
750
751                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
752                 rcu_read_unlock();
753                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
754                        np->name, HIPQUAD(np->local_ip));
755         }
756
757         if (np->rx_hook) {
758                 spin_lock_irqsave(&npinfo->rx_lock, flags);
759                 npinfo->rx_np = np;
760                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
761         }
762
763         /* fill up the skb queue */
764         refill_skbs();
765
766         /* last thing to do is link it to the net device structure */
767         ndev->npinfo = npinfo;
768
769         /* avoid racing with NAPI reading npinfo */
770         synchronize_rcu();
771
772         return 0;
773
774  release:
775         if (!ndev->npinfo)
776                 kfree(npinfo);
777         np->dev = NULL;
778         dev_put(ndev);
779         return err;
780 }
781
782 static int __init netpoll_init(void)
783 {
784         skb_queue_head_init(&skb_pool);
785         return 0;
786 }
787 core_initcall(netpoll_init);
788
789 void netpoll_cleanup(struct netpoll *np)
790 {
791         struct netpoll_info *npinfo;
792         unsigned long flags;
793
794         if (np->dev) {
795                 npinfo = np->dev->npinfo;
796                 if (npinfo) {
797                         if (npinfo->rx_np == np) {
798                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
799                                 npinfo->rx_np = NULL;
800                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
801                         }
802
803                         if (atomic_dec_and_test(&npinfo->refcnt)) {
804                                 skb_queue_purge(&npinfo->arp_tx);
805                                 skb_queue_purge(&npinfo->txq);
806                                 cancel_rearming_delayed_work(&npinfo->tx_work);
807
808                                 /* clean after last, unfinished work */
809                                 __skb_queue_purge(&npinfo->txq);
810                                 kfree(npinfo);
811                                 np->dev->npinfo = NULL;
812                         }
813                 }
814
815                 dev_put(np->dev);
816         }
817
818         np->dev = NULL;
819 }
820
821 int netpoll_trap(void)
822 {
823         return atomic_read(&trapped);
824 }
825
826 void netpoll_set_trap(int trap)
827 {
828         if (trap)
829                 atomic_inc(&trapped);
830         else
831                 atomic_dec(&trapped);
832 }
833
834 EXPORT_SYMBOL(netpoll_set_trap);
835 EXPORT_SYMBOL(netpoll_trap);
836 EXPORT_SYMBOL(netpoll_print_options);
837 EXPORT_SYMBOL(netpoll_parse_options);
838 EXPORT_SYMBOL(netpoll_setup);
839 EXPORT_SYMBOL(netpoll_cleanup);
840 EXPORT_SYMBOL(netpoll_send_udp);
841 EXPORT_SYMBOL(netpoll_poll);