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