a0efdd7a6b375951546319eb9717167edd301972
[linux-3.10.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                     dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
71                         skb_queue_head(&npinfo->txq, skb);
72                         netif_tx_unlock(dev);
73                         local_irq_restore(flags);
74
75                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
76                         return;
77                 }
78                 netif_tx_unlock(dev);
79                 local_irq_restore(flags);
80         }
81 }
82
83 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
84                             unsigned short ulen, __be32 saddr, __be32 daddr)
85 {
86         __wsum psum;
87
88         if (uh->check == 0 || skb_csum_unnecessary(skb))
89                 return 0;
90
91         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
92
93         if (skb->ip_summed == CHECKSUM_COMPLETE &&
94             !csum_fold(csum_add(psum, skb->csum)))
95                 return 0;
96
97         skb->csum = psum;
98
99         return __skb_checksum_complete(skb);
100 }
101
102 /*
103  * Check whether delayed processing was scheduled for our NIC. If so,
104  * we attempt to grab the poll lock and use ->poll() to pump the card.
105  * If this fails, either we've recursed in ->poll() or it's already
106  * running on another CPU.
107  *
108  * Note: we don't mask interrupts with this lock because we're using
109  * trylock here and interrupts are already disabled in the softirq
110  * case. Further, we test the poll_owner to avoid recursion on UP
111  * systems where the lock doesn't exist.
112  *
113  * In cases where there is bi-directional communications, reading only
114  * one message at a time can lead to packets being dropped by the
115  * network adapter, forcing superfluous retries and possibly timeouts.
116  * Thus, we set our budget to greater than 1.
117  */
118 static void poll_napi(struct netpoll *np)
119 {
120         struct netpoll_info *npinfo = np->dev->npinfo;
121         int budget = 16;
122
123         if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
124             npinfo->poll_owner != smp_processor_id() &&
125             spin_trylock(&npinfo->poll_lock)) {
126                 npinfo->rx_flags |= NETPOLL_RX_DROP;
127                 atomic_inc(&trapped);
128
129                 np->dev->poll(np->dev, &budget);
130
131                 atomic_dec(&trapped);
132                 npinfo->rx_flags &= ~NETPOLL_RX_DROP;
133                 spin_unlock(&npinfo->poll_lock);
134         }
135 }
136
137 static void service_arp_queue(struct netpoll_info *npi)
138 {
139         struct sk_buff *skb;
140
141         if (unlikely(!npi))
142                 return;
143
144         skb = skb_dequeue(&npi->arp_tx);
145
146         while (skb != NULL) {
147                 arp_reply(skb);
148                 skb = skb_dequeue(&npi->arp_tx);
149         }
150 }
151
152 void netpoll_poll(struct netpoll *np)
153 {
154         if (!np->dev || !netif_running(np->dev) || !np->dev->poll_controller)
155                 return;
156
157         /* Process pending work on NIC */
158         np->dev->poll_controller(np->dev);
159         if (np->dev->poll)
160                 poll_napi(np);
161
162         service_arp_queue(np->dev->npinfo);
163
164         zap_completion_queue();
165 }
166
167 static void refill_skbs(void)
168 {
169         struct sk_buff *skb;
170         unsigned long flags;
171
172         spin_lock_irqsave(&skb_pool.lock, flags);
173         while (skb_pool.qlen < MAX_SKBS) {
174                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
175                 if (!skb)
176                         break;
177
178                 __skb_queue_tail(&skb_pool, skb);
179         }
180         spin_unlock_irqrestore(&skb_pool.lock, flags);
181 }
182
183 static void zap_completion_queue(void)
184 {
185         unsigned long flags;
186         struct softnet_data *sd = &get_cpu_var(softnet_data);
187
188         if (sd->completion_queue) {
189                 struct sk_buff *clist;
190
191                 local_irq_save(flags);
192                 clist = sd->completion_queue;
193                 sd->completion_queue = NULL;
194                 local_irq_restore(flags);
195
196                 while (clist != NULL) {
197                         struct sk_buff *skb = clist;
198                         clist = clist->next;
199                         if (skb->destructor)
200                                 dev_kfree_skb_any(skb); /* put this one back */
201                         else
202                                 __kfree_skb(skb);
203                 }
204         }
205
206         put_cpu_var(softnet_data);
207 }
208
209 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
210 {
211         int count = 0;
212         struct sk_buff *skb;
213
214         zap_completion_queue();
215         refill_skbs();
216 repeat:
217
218         skb = alloc_skb(len, GFP_ATOMIC);
219         if (!skb)
220                 skb = skb_dequeue(&skb_pool);
221
222         if (!skb) {
223                 if (++count < 10) {
224                         netpoll_poll(np);
225                         goto repeat;
226                 }
227                 return NULL;
228         }
229
230         atomic_set(&skb->users, 1);
231         skb_reserve(skb, reserve);
232         return skb;
233 }
234
235 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
236 {
237         int status = NETDEV_TX_BUSY;
238         unsigned long tries;
239         struct net_device *dev = np->dev;
240         struct netpoll_info *npinfo = np->dev->npinfo;
241
242         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
243                 __kfree_skb(skb);
244                 return;
245         }
246
247         /* don't get messages out of order, and no recursion */
248         if (skb_queue_len(&npinfo->txq) == 0 &&
249                     npinfo->poll_owner != smp_processor_id()) {
250                 unsigned long flags;
251
252                 local_irq_save(flags);
253                 /* try until next clock tick */
254                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
255                      tries > 0; --tries) {
256                         if (netif_tx_trylock(dev)) {
257                                 if (!netif_queue_stopped(dev))
258                                         status = dev->hard_start_xmit(skb, dev);
259                                 netif_tx_unlock(dev);
260
261                                 if (status == NETDEV_TX_OK)
262                                         break;
263
264                         }
265
266                         /* tickle device maybe there is some cleanup */
267                         netpoll_poll(np);
268
269                         udelay(USEC_PER_POLL);
270                 }
271                 local_irq_restore(flags);
272         }
273
274         if (status != NETDEV_TX_OK) {
275                 skb_queue_tail(&npinfo->txq, skb);
276                 schedule_delayed_work(&npinfo->tx_work,0);
277         }
278 }
279
280 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
281 {
282         int total_len, eth_len, ip_len, udp_len;
283         struct sk_buff *skb;
284         struct udphdr *udph;
285         struct iphdr *iph;
286         struct ethhdr *eth;
287
288         udp_len = len + sizeof(*udph);
289         ip_len = eth_len = udp_len + sizeof(*iph);
290         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
291
292         skb = find_skb(np, total_len, total_len - len);
293         if (!skb)
294                 return;
295
296         skb_copy_to_linear_data(skb, msg, len);
297         skb->len += len;
298
299         skb_push(skb, sizeof(*udph));
300         skb_reset_transport_header(skb);
301         udph = udp_hdr(skb);
302         udph->source = htons(np->local_port);
303         udph->dest = htons(np->remote_port);
304         udph->len = htons(udp_len);
305         udph->check = 0;
306         udph->check = csum_tcpudp_magic(htonl(np->local_ip),
307                                         htonl(np->remote_ip),
308                                         udp_len, IPPROTO_UDP,
309                                         csum_partial((unsigned char *)udph, udp_len, 0));
310         if (udph->check == 0)
311                 udph->check = CSUM_MANGLED_0;
312
313         skb_push(skb, sizeof(*iph));
314         skb_reset_network_header(skb);
315         iph = ip_hdr(skb);
316
317         /* iph->version = 4; iph->ihl = 5; */
318         put_unaligned(0x45, (unsigned char *)iph);
319         iph->tos      = 0;
320         put_unaligned(htons(ip_len), &(iph->tot_len));
321         iph->id       = 0;
322         iph->frag_off = 0;
323         iph->ttl      = 64;
324         iph->protocol = IPPROTO_UDP;
325         iph->check    = 0;
326         put_unaligned(htonl(np->local_ip), &(iph->saddr));
327         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
328         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
329
330         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
331         skb_reset_mac_header(skb);
332         skb->protocol = eth->h_proto = htons(ETH_P_IP);
333         memcpy(eth->h_source, np->local_mac, 6);
334         memcpy(eth->h_dest, np->remote_mac, 6);
335
336         skb->dev = np->dev;
337
338         netpoll_send_skb(np, skb);
339 }
340
341 static void arp_reply(struct sk_buff *skb)
342 {
343         struct netpoll_info *npinfo = skb->dev->npinfo;
344         struct arphdr *arp;
345         unsigned char *arp_ptr;
346         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
347         __be32 sip, tip;
348         unsigned char *sha;
349         struct sk_buff *send_skb;
350         struct netpoll *np = NULL;
351
352         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
353                 np = npinfo->rx_np;
354         if (!np)
355                 return;
356
357         /* No arp on this interface */
358         if (skb->dev->flags & IFF_NOARP)
359                 return;
360
361         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
362                                  (2 * skb->dev->addr_len) +
363                                  (2 * sizeof(u32)))))
364                 return;
365
366         skb_reset_network_header(skb);
367         skb_reset_transport_header(skb);
368         arp = arp_hdr(skb);
369
370         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
371              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
372             arp->ar_pro != htons(ETH_P_IP) ||
373             arp->ar_op != htons(ARPOP_REQUEST))
374                 return;
375
376         arp_ptr = (unsigned char *)(arp+1);
377         /* save the location of the src hw addr */
378         sha = arp_ptr;
379         arp_ptr += skb->dev->addr_len;
380         memcpy(&sip, arp_ptr, 4);
381         arp_ptr += 4;
382         /* if we actually cared about dst hw addr, it would get copied here */
383         arp_ptr += skb->dev->addr_len;
384         memcpy(&tip, arp_ptr, 4);
385
386         /* Should we ignore arp? */
387         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
388                 return;
389
390         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
391         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
392                             LL_RESERVED_SPACE(np->dev));
393
394         if (!send_skb)
395                 return;
396
397         skb_reset_network_header(send_skb);
398         arp = (struct arphdr *) skb_put(send_skb, size);
399         send_skb->dev = skb->dev;
400         send_skb->protocol = htons(ETH_P_ARP);
401
402         /* Fill the device header for the ARP frame */
403
404         if (np->dev->hard_header &&
405             np->dev->hard_header(send_skb, skb->dev, ptype,
406                                  sha, np->local_mac,
407                                  send_skb->len) < 0) {
408                 kfree_skb(send_skb);
409                 return;
410         }
411
412         /*
413          * Fill out the arp protocol part.
414          *
415          * we only support ethernet device type,
416          * which (according to RFC 1390) should always equal 1 (Ethernet).
417          */
418
419         arp->ar_hrd = htons(np->dev->type);
420         arp->ar_pro = htons(ETH_P_IP);
421         arp->ar_hln = np->dev->addr_len;
422         arp->ar_pln = 4;
423         arp->ar_op = htons(type);
424
425         arp_ptr=(unsigned char *)(arp + 1);
426         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
427         arp_ptr += np->dev->addr_len;
428         memcpy(arp_ptr, &tip, 4);
429         arp_ptr += 4;
430         memcpy(arp_ptr, sha, np->dev->addr_len);
431         arp_ptr += np->dev->addr_len;
432         memcpy(arp_ptr, &sip, 4);
433
434         netpoll_send_skb(np, send_skb);
435 }
436
437 int __netpoll_rx(struct sk_buff *skb)
438 {
439         int proto, len, ulen;
440         struct iphdr *iph;
441         struct udphdr *uh;
442         struct netpoll_info *npi = skb->dev->npinfo;
443         struct netpoll *np = npi->rx_np;
444
445         if (!np)
446                 goto out;
447         if (skb->dev->type != ARPHRD_ETHER)
448                 goto out;
449
450         /* check if netpoll clients need ARP */
451         if (skb->protocol == htons(ETH_P_ARP) &&
452             atomic_read(&trapped)) {
453                 skb_queue_tail(&npi->arp_tx, skb);
454                 return 1;
455         }
456
457         proto = ntohs(eth_hdr(skb)->h_proto);
458         if (proto != ETH_P_IP)
459                 goto out;
460         if (skb->pkt_type == PACKET_OTHERHOST)
461                 goto out;
462         if (skb_shared(skb))
463                 goto out;
464
465         iph = (struct iphdr *)skb->data;
466         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
467                 goto out;
468         if (iph->ihl < 5 || iph->version != 4)
469                 goto out;
470         if (!pskb_may_pull(skb, iph->ihl*4))
471                 goto out;
472         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
473                 goto out;
474
475         len = ntohs(iph->tot_len);
476         if (skb->len < len || len < iph->ihl*4)
477                 goto out;
478
479         /*
480          * Our transport medium may have padded the buffer out.
481          * Now We trim to the true length of the frame.
482          */
483         if (pskb_trim_rcsum(skb, len))
484                 goto out;
485
486         if (iph->protocol != IPPROTO_UDP)
487                 goto out;
488
489         len -= iph->ihl*4;
490         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
491         ulen = ntohs(uh->len);
492
493         if (ulen != len)
494                 goto out;
495         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
496                 goto out;
497         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
498                 goto out;
499         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
500                 goto out;
501         if (np->local_port && np->local_port != ntohs(uh->dest))
502                 goto out;
503
504         np->rx_hook(np, ntohs(uh->source),
505                     (char *)(uh+1),
506                     ulen - sizeof(struct udphdr));
507
508         kfree_skb(skb);
509         return 1;
510
511 out:
512         if (atomic_read(&trapped)) {
513                 kfree_skb(skb);
514                 return 1;
515         }
516
517         return 0;
518 }
519
520 int netpoll_parse_options(struct netpoll *np, char *opt)
521 {
522         char *cur=opt, *delim;
523
524         if (*cur != '@') {
525                 if ((delim = strchr(cur, '@')) == NULL)
526                         goto parse_failed;
527                 *delim = 0;
528                 np->local_port = simple_strtol(cur, NULL, 10);
529                 cur = delim;
530         }
531         cur++;
532         printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
533
534         if (*cur != '/') {
535                 if ((delim = strchr(cur, '/')) == NULL)
536                         goto parse_failed;
537                 *delim = 0;
538                 np->local_ip = ntohl(in_aton(cur));
539                 cur = delim;
540
541                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
542                        np->name, HIPQUAD(np->local_ip));
543         }
544         cur++;
545
546         if (*cur != ',') {
547                 /* parse out dev name */
548                 if ((delim = strchr(cur, ',')) == NULL)
549                         goto parse_failed;
550                 *delim = 0;
551                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
552                 cur = delim;
553         }
554         cur++;
555
556         printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
557
558         if (*cur != '@') {
559                 /* dst port */
560                 if ((delim = strchr(cur, '@')) == NULL)
561                         goto parse_failed;
562                 *delim = 0;
563                 np->remote_port = simple_strtol(cur, NULL, 10);
564                 cur = delim;
565         }
566         cur++;
567         printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
568
569         /* dst ip */
570         if ((delim = strchr(cur, '/')) == NULL)
571                 goto parse_failed;
572         *delim = 0;
573         np->remote_ip = ntohl(in_aton(cur));
574         cur = delim + 1;
575
576         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
577                np->name, HIPQUAD(np->remote_ip));
578
579         if (*cur != 0) {
580                 /* MAC address */
581                 if ((delim = strchr(cur, ':')) == NULL)
582                         goto parse_failed;
583                 *delim = 0;
584                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
585                 cur = delim + 1;
586                 if ((delim = strchr(cur, ':')) == NULL)
587                         goto parse_failed;
588                 *delim = 0;
589                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
590                 cur = delim + 1;
591                 if ((delim = strchr(cur, ':')) == NULL)
592                         goto parse_failed;
593                 *delim = 0;
594                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
595                 cur = delim + 1;
596                 if ((delim = strchr(cur, ':')) == NULL)
597                         goto parse_failed;
598                 *delim = 0;
599                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
600                 cur = delim + 1;
601                 if ((delim = strchr(cur, ':')) == NULL)
602                         goto parse_failed;
603                 *delim = 0;
604                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
605                 cur = delim + 1;
606                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
607         }
608
609         printk(KERN_INFO "%s: remote ethernet address "
610                "%02x:%02x:%02x:%02x:%02x:%02x\n",
611                np->name,
612                np->remote_mac[0],
613                np->remote_mac[1],
614                np->remote_mac[2],
615                np->remote_mac[3],
616                np->remote_mac[4],
617                np->remote_mac[5]);
618
619         return 0;
620
621  parse_failed:
622         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
623                np->name, cur);
624         return -1;
625 }
626
627 int netpoll_setup(struct netpoll *np)
628 {
629         struct net_device *ndev = NULL;
630         struct in_device *in_dev;
631         struct netpoll_info *npinfo;
632         unsigned long flags;
633         int err;
634
635         if (np->dev_name)
636                 ndev = dev_get_by_name(np->dev_name);
637         if (!ndev) {
638                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
639                        np->name, np->dev_name);
640                 return -ENODEV;
641         }
642
643         np->dev = ndev;
644         if (!ndev->npinfo) {
645                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
646                 if (!npinfo) {
647                         err = -ENOMEM;
648                         goto release;
649                 }
650
651                 npinfo->rx_flags = 0;
652                 npinfo->rx_np = NULL;
653                 spin_lock_init(&npinfo->poll_lock);
654                 npinfo->poll_owner = -1;
655
656                 spin_lock_init(&npinfo->rx_lock);
657                 skb_queue_head_init(&npinfo->arp_tx);
658                 skb_queue_head_init(&npinfo->txq);
659                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
660
661                 atomic_set(&npinfo->refcnt, 1);
662         } else {
663                 npinfo = ndev->npinfo;
664                 atomic_inc(&npinfo->refcnt);
665         }
666
667         if (!ndev->poll_controller) {
668                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
669                        np->name, np->dev_name);
670                 err = -ENOTSUPP;
671                 goto release;
672         }
673
674         if (!netif_running(ndev)) {
675                 unsigned long atmost, atleast;
676
677                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
678                        np->name, np->dev_name);
679
680                 rtnl_lock();
681                 err = dev_open(ndev);
682                 rtnl_unlock();
683
684                 if (err) {
685                         printk(KERN_ERR "%s: failed to open %s\n",
686                                np->name, ndev->name);
687                         goto release;
688                 }
689
690                 atleast = jiffies + HZ/10;
691                 atmost = jiffies + 4*HZ;
692                 while (!netif_carrier_ok(ndev)) {
693                         if (time_after(jiffies, atmost)) {
694                                 printk(KERN_NOTICE
695                                        "%s: timeout waiting for carrier\n",
696                                        np->name);
697                                 break;
698                         }
699                         cond_resched();
700                 }
701
702                 /* If carrier appears to come up instantly, we don't
703                  * trust it and pause so that we don't pump all our
704                  * queued console messages into the bitbucket.
705                  */
706
707                 if (time_before(jiffies, atleast)) {
708                         printk(KERN_NOTICE "%s: carrier detect appears"
709                                " untrustworthy, waiting 4 seconds\n",
710                                np->name);
711                         msleep(4000);
712                 }
713         }
714
715         if (is_zero_ether_addr(np->local_mac) && ndev->dev_addr)
716                 memcpy(np->local_mac, ndev->dev_addr, 6);
717
718         if (!np->local_ip) {
719                 rcu_read_lock();
720                 in_dev = __in_dev_get_rcu(ndev);
721
722                 if (!in_dev || !in_dev->ifa_list) {
723                         rcu_read_unlock();
724                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
725                                np->name, np->dev_name);
726                         err = -EDESTADDRREQ;
727                         goto release;
728                 }
729
730                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
731                 rcu_read_unlock();
732                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
733                        np->name, HIPQUAD(np->local_ip));
734         }
735
736         if (np->rx_hook) {
737                 spin_lock_irqsave(&npinfo->rx_lock, flags);
738                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
739                 npinfo->rx_np = np;
740                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
741         }
742
743         /* fill up the skb queue */
744         refill_skbs();
745
746         /* last thing to do is link it to the net device structure */
747         ndev->npinfo = npinfo;
748
749         /* avoid racing with NAPI reading npinfo */
750         synchronize_rcu();
751
752         return 0;
753
754  release:
755         if (!ndev->npinfo)
756                 kfree(npinfo);
757         np->dev = NULL;
758         dev_put(ndev);
759         return err;
760 }
761
762 static int __init netpoll_init(void)
763 {
764         skb_queue_head_init(&skb_pool);
765         return 0;
766 }
767 core_initcall(netpoll_init);
768
769 void netpoll_cleanup(struct netpoll *np)
770 {
771         struct netpoll_info *npinfo;
772         unsigned long flags;
773
774         if (np->dev) {
775                 npinfo = np->dev->npinfo;
776                 if (npinfo) {
777                         if (npinfo->rx_np == np) {
778                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
779                                 npinfo->rx_np = NULL;
780                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
781                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
782                         }
783
784                         np->dev->npinfo = NULL;
785                         if (atomic_dec_and_test(&npinfo->refcnt)) {
786                                 skb_queue_purge(&npinfo->arp_tx);
787                                 skb_queue_purge(&npinfo->txq);
788                                 cancel_rearming_delayed_work(&npinfo->tx_work);
789
790                                 /* clean after last, unfinished work */
791                                 if (!skb_queue_empty(&npinfo->txq)) {
792                                         struct sk_buff *skb;
793                                         skb = __skb_dequeue(&npinfo->txq);
794                                         kfree_skb(skb);
795                                 }
796                                 kfree(npinfo);
797                         }
798                 }
799
800                 dev_put(np->dev);
801         }
802
803         np->dev = NULL;
804 }
805
806 int netpoll_trap(void)
807 {
808         return atomic_read(&trapped);
809 }
810
811 void netpoll_set_trap(int trap)
812 {
813         if (trap)
814                 atomic_inc(&trapped);
815         else
816                 atomic_dec(&trapped);
817 }
818
819 EXPORT_SYMBOL(netpoll_set_trap);
820 EXPORT_SYMBOL(netpoll_trap);
821 EXPORT_SYMBOL(netpoll_parse_options);
822 EXPORT_SYMBOL(netpoll_setup);
823 EXPORT_SYMBOL(netpoll_cleanup);
824 EXPORT_SYMBOL(netpoll_send_udp);
825 EXPORT_SYMBOL(netpoll_poll);