net: Optimize hard_start_xmit() return checking
[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/moduleparam.h>
13 #include <linux/netdevice.h>
14 #include <linux/etherdevice.h>
15 #include <linux/string.h>
16 #include <linux/if_arp.h>
17 #include <linux/inetdevice.h>
18 #include <linux/inet.h>
19 #include <linux/interrupt.h>
20 #include <linux/netpoll.h>
21 #include <linux/sched.h>
22 #include <linux/delay.h>
23 #include <linux/rcupdate.h>
24 #include <linux/workqueue.h>
25 #include <net/tcp.h>
26 #include <net/udp.h>
27 #include <asm/unaligned.h>
28 #include <trace/events/napi.h>
29
30 /*
31  * We maintain a small pool of fully-sized skbs, to make sure the
32  * message gets out even in extreme OOM situations.
33  */
34
35 #define MAX_UDP_CHUNK 1460
36 #define MAX_SKBS 32
37 #define MAX_QUEUE_DEPTH (MAX_SKBS / 2)
38
39 static struct sk_buff_head skb_pool;
40
41 static atomic_t trapped;
42
43 #define USEC_PER_POLL   50
44 #define NETPOLL_RX_ENABLED  1
45 #define NETPOLL_RX_DROP     2
46
47 #define MAX_SKB_SIZE \
48                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
49                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
50
51 static void zap_completion_queue(void);
52 static void arp_reply(struct sk_buff *skb);
53
54 static unsigned int carrier_timeout = 4;
55 module_param(carrier_timeout, uint, 0644);
56
57 static void queue_process(struct work_struct *work)
58 {
59         struct netpoll_info *npinfo =
60                 container_of(work, struct netpoll_info, tx_work.work);
61         struct sk_buff *skb;
62         unsigned long flags;
63
64         while ((skb = skb_dequeue(&npinfo->txq))) {
65                 struct net_device *dev = skb->dev;
66                 const struct net_device_ops *ops = dev->netdev_ops;
67                 struct netdev_queue *txq;
68
69                 if (!netif_device_present(dev) || !netif_running(dev)) {
70                         __kfree_skb(skb);
71                         continue;
72                 }
73
74                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
75
76                 local_irq_save(flags);
77                 __netif_tx_lock(txq, smp_processor_id());
78                 if (netif_tx_queue_stopped(txq) ||
79                     netif_tx_queue_frozen(txq) ||
80                     ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
81                         skb_queue_head(&npinfo->txq, skb);
82                         __netif_tx_unlock(txq);
83                         local_irq_restore(flags);
84
85                         schedule_delayed_work(&npinfo->tx_work, HZ/10);
86                         return;
87                 }
88                 __netif_tx_unlock(txq);
89                 local_irq_restore(flags);
90         }
91 }
92
93 static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
94                             unsigned short ulen, __be32 saddr, __be32 daddr)
95 {
96         __wsum psum;
97
98         if (uh->check == 0 || skb_csum_unnecessary(skb))
99                 return 0;
100
101         psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
102
103         if (skb->ip_summed == CHECKSUM_COMPLETE &&
104             !csum_fold(csum_add(psum, skb->csum)))
105                 return 0;
106
107         skb->csum = psum;
108
109         return __skb_checksum_complete(skb);
110 }
111
112 /*
113  * Check whether delayed processing was scheduled for our NIC. If so,
114  * we attempt to grab the poll lock and use ->poll() to pump the card.
115  * If this fails, either we've recursed in ->poll() or it's already
116  * running on another CPU.
117  *
118  * Note: we don't mask interrupts with this lock because we're using
119  * trylock here and interrupts are already disabled in the softirq
120  * case. Further, we test the poll_owner to avoid recursion on UP
121  * systems where the lock doesn't exist.
122  *
123  * In cases where there is bi-directional communications, reading only
124  * one message at a time can lead to packets being dropped by the
125  * network adapter, forcing superfluous retries and possibly timeouts.
126  * Thus, we set our budget to greater than 1.
127  */
128 static int poll_one_napi(struct netpoll_info *npinfo,
129                          struct napi_struct *napi, int budget)
130 {
131         int work;
132
133         /* net_rx_action's ->poll() invocations and our's are
134          * synchronized by this test which is only made while
135          * holding the napi->poll_lock.
136          */
137         if (!test_bit(NAPI_STATE_SCHED, &napi->state))
138                 return budget;
139
140         npinfo->rx_flags |= NETPOLL_RX_DROP;
141         atomic_inc(&trapped);
142         set_bit(NAPI_STATE_NPSVC, &napi->state);
143
144         work = napi->poll(napi, budget);
145         trace_napi_poll(napi);
146
147         clear_bit(NAPI_STATE_NPSVC, &napi->state);
148         atomic_dec(&trapped);
149         npinfo->rx_flags &= ~NETPOLL_RX_DROP;
150
151         return budget - work;
152 }
153
154 static void poll_napi(struct net_device *dev)
155 {
156         struct napi_struct *napi;
157         int budget = 16;
158
159         list_for_each_entry(napi, &dev->napi_list, dev_list) {
160                 if (napi->poll_owner != smp_processor_id() &&
161                     spin_trylock(&napi->poll_lock)) {
162                         budget = poll_one_napi(dev->npinfo, napi, budget);
163                         spin_unlock(&napi->poll_lock);
164
165                         if (!budget)
166                                 break;
167                 }
168         }
169 }
170
171 static void service_arp_queue(struct netpoll_info *npi)
172 {
173         if (npi) {
174                 struct sk_buff *skb;
175
176                 while ((skb = skb_dequeue(&npi->arp_tx)))
177                         arp_reply(skb);
178         }
179 }
180
181 void netpoll_poll(struct netpoll *np)
182 {
183         struct net_device *dev = np->dev;
184         const struct net_device_ops *ops;
185
186         if (!dev || !netif_running(dev))
187                 return;
188
189         ops = dev->netdev_ops;
190         if (!ops->ndo_poll_controller)
191                 return;
192
193         /* Process pending work on NIC */
194         ops->ndo_poll_controller(dev);
195
196         poll_napi(dev);
197
198         service_arp_queue(dev->npinfo);
199
200         zap_completion_queue();
201 }
202
203 static void refill_skbs(void)
204 {
205         struct sk_buff *skb;
206         unsigned long flags;
207
208         spin_lock_irqsave(&skb_pool.lock, flags);
209         while (skb_pool.qlen < MAX_SKBS) {
210                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
211                 if (!skb)
212                         break;
213
214                 __skb_queue_tail(&skb_pool, skb);
215         }
216         spin_unlock_irqrestore(&skb_pool.lock, flags);
217 }
218
219 static void zap_completion_queue(void)
220 {
221         unsigned long flags;
222         struct softnet_data *sd = &get_cpu_var(softnet_data);
223
224         if (sd->completion_queue) {
225                 struct sk_buff *clist;
226
227                 local_irq_save(flags);
228                 clist = sd->completion_queue;
229                 sd->completion_queue = NULL;
230                 local_irq_restore(flags);
231
232                 while (clist != NULL) {
233                         struct sk_buff *skb = clist;
234                         clist = clist->next;
235                         if (skb->destructor) {
236                                 atomic_inc(&skb->users);
237                                 dev_kfree_skb_any(skb); /* put this one back */
238                         } else {
239                                 __kfree_skb(skb);
240                         }
241                 }
242         }
243
244         put_cpu_var(softnet_data);
245 }
246
247 static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
248 {
249         int count = 0;
250         struct sk_buff *skb;
251
252         zap_completion_queue();
253         refill_skbs();
254 repeat:
255
256         skb = alloc_skb(len, GFP_ATOMIC);
257         if (!skb)
258                 skb = skb_dequeue(&skb_pool);
259
260         if (!skb) {
261                 if (++count < 10) {
262                         netpoll_poll(np);
263                         goto repeat;
264                 }
265                 return NULL;
266         }
267
268         atomic_set(&skb->users, 1);
269         skb_reserve(skb, reserve);
270         return skb;
271 }
272
273 static int netpoll_owner_active(struct net_device *dev)
274 {
275         struct napi_struct *napi;
276
277         list_for_each_entry(napi, &dev->napi_list, dev_list) {
278                 if (napi->poll_owner == smp_processor_id())
279                         return 1;
280         }
281         return 0;
282 }
283
284 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
285 {
286         int status = NETDEV_TX_BUSY;
287         unsigned long tries;
288         struct net_device *dev = np->dev;
289         const struct net_device_ops *ops = dev->netdev_ops;
290         struct netpoll_info *npinfo = np->dev->npinfo;
291
292         if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
293                 __kfree_skb(skb);
294                 return;
295         }
296
297         /* don't get messages out of order, and no recursion */
298         if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
299                 struct netdev_queue *txq;
300                 unsigned long flags;
301
302                 txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
303
304                 local_irq_save(flags);
305                 /* try until next clock tick */
306                 for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
307                      tries > 0; --tries) {
308                         if (__netif_tx_trylock(txq)) {
309                                 if (!netif_tx_queue_stopped(txq)) {
310                                         status = ops->ndo_start_xmit(skb, dev);
311                                         if (status == NETDEV_TX_OK)
312                                                 txq_trans_update(txq);
313                                 }
314                                 __netif_tx_unlock(txq);
315
316                                 if (status == NETDEV_TX_OK)
317                                         break;
318
319                         }
320
321                         /* tickle device maybe there is some cleanup */
322                         netpoll_poll(np);
323
324                         udelay(USEC_PER_POLL);
325                 }
326
327                 WARN_ONCE(!irqs_disabled(),
328                         "netpoll_send_skb(): %s enabled interrupts in poll (%pF)\n",
329                         dev->name, ops->ndo_start_xmit);
330
331                 local_irq_restore(flags);
332         }
333
334         if (status != NETDEV_TX_OK) {
335                 skb_queue_tail(&npinfo->txq, skb);
336                 schedule_delayed_work(&npinfo->tx_work,0);
337         }
338 }
339
340 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
341 {
342         int total_len, eth_len, ip_len, udp_len;
343         struct sk_buff *skb;
344         struct udphdr *udph;
345         struct iphdr *iph;
346         struct ethhdr *eth;
347
348         udp_len = len + sizeof(*udph);
349         ip_len = eth_len = udp_len + sizeof(*iph);
350         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
351
352         skb = find_skb(np, total_len, total_len - len);
353         if (!skb)
354                 return;
355
356         skb_copy_to_linear_data(skb, msg, len);
357         skb->len += len;
358
359         skb_push(skb, sizeof(*udph));
360         skb_reset_transport_header(skb);
361         udph = udp_hdr(skb);
362         udph->source = htons(np->local_port);
363         udph->dest = htons(np->remote_port);
364         udph->len = htons(udp_len);
365         udph->check = 0;
366         udph->check = csum_tcpudp_magic(np->local_ip,
367                                         np->remote_ip,
368                                         udp_len, IPPROTO_UDP,
369                                         csum_partial(udph, udp_len, 0));
370         if (udph->check == 0)
371                 udph->check = CSUM_MANGLED_0;
372
373         skb_push(skb, sizeof(*iph));
374         skb_reset_network_header(skb);
375         iph = ip_hdr(skb);
376
377         /* iph->version = 4; iph->ihl = 5; */
378         put_unaligned(0x45, (unsigned char *)iph);
379         iph->tos      = 0;
380         put_unaligned(htons(ip_len), &(iph->tot_len));
381         iph->id       = 0;
382         iph->frag_off = 0;
383         iph->ttl      = 64;
384         iph->protocol = IPPROTO_UDP;
385         iph->check    = 0;
386         put_unaligned(np->local_ip, &(iph->saddr));
387         put_unaligned(np->remote_ip, &(iph->daddr));
388         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
389
390         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
391         skb_reset_mac_header(skb);
392         skb->protocol = eth->h_proto = htons(ETH_P_IP);
393         memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
394         memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
395
396         skb->dev = np->dev;
397
398         netpoll_send_skb(np, skb);
399 }
400
401 static void arp_reply(struct sk_buff *skb)
402 {
403         struct netpoll_info *npinfo = skb->dev->npinfo;
404         struct arphdr *arp;
405         unsigned char *arp_ptr;
406         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
407         __be32 sip, tip;
408         unsigned char *sha;
409         struct sk_buff *send_skb;
410         struct netpoll *np = NULL;
411
412         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
413                 np = npinfo->rx_np;
414         if (!np)
415                 return;
416
417         /* No arp on this interface */
418         if (skb->dev->flags & IFF_NOARP)
419                 return;
420
421         if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
422                 return;
423
424         skb_reset_network_header(skb);
425         skb_reset_transport_header(skb);
426         arp = arp_hdr(skb);
427
428         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
429              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
430             arp->ar_pro != htons(ETH_P_IP) ||
431             arp->ar_op != htons(ARPOP_REQUEST))
432                 return;
433
434         arp_ptr = (unsigned char *)(arp+1);
435         /* save the location of the src hw addr */
436         sha = arp_ptr;
437         arp_ptr += skb->dev->addr_len;
438         memcpy(&sip, arp_ptr, 4);
439         arp_ptr += 4;
440         /* if we actually cared about dst hw addr, it would get copied here */
441         arp_ptr += skb->dev->addr_len;
442         memcpy(&tip, arp_ptr, 4);
443
444         /* Should we ignore arp? */
445         if (tip != np->local_ip ||
446             ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
447                 return;
448
449         size = arp_hdr_len(skb->dev);
450         send_skb = find_skb(np, size + LL_ALLOCATED_SPACE(np->dev),
451                             LL_RESERVED_SPACE(np->dev));
452
453         if (!send_skb)
454                 return;
455
456         skb_reset_network_header(send_skb);
457         arp = (struct arphdr *) skb_put(send_skb, size);
458         send_skb->dev = skb->dev;
459         send_skb->protocol = htons(ETH_P_ARP);
460
461         /* Fill the device header for the ARP frame */
462         if (dev_hard_header(send_skb, skb->dev, ptype,
463                             sha, np->dev->dev_addr,
464                             send_skb->len) < 0) {
465                 kfree_skb(send_skb);
466                 return;
467         }
468
469         /*
470          * Fill out the arp protocol part.
471          *
472          * we only support ethernet device type,
473          * which (according to RFC 1390) should always equal 1 (Ethernet).
474          */
475
476         arp->ar_hrd = htons(np->dev->type);
477         arp->ar_pro = htons(ETH_P_IP);
478         arp->ar_hln = np->dev->addr_len;
479         arp->ar_pln = 4;
480         arp->ar_op = htons(type);
481
482         arp_ptr=(unsigned char *)(arp + 1);
483         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
484         arp_ptr += np->dev->addr_len;
485         memcpy(arp_ptr, &tip, 4);
486         arp_ptr += 4;
487         memcpy(arp_ptr, sha, np->dev->addr_len);
488         arp_ptr += np->dev->addr_len;
489         memcpy(arp_ptr, &sip, 4);
490
491         netpoll_send_skb(np, send_skb);
492 }
493
494 int __netpoll_rx(struct sk_buff *skb)
495 {
496         int proto, len, ulen;
497         struct iphdr *iph;
498         struct udphdr *uh;
499         struct netpoll_info *npi = skb->dev->npinfo;
500         struct netpoll *np = npi->rx_np;
501
502         if (!np)
503                 goto out;
504         if (skb->dev->type != ARPHRD_ETHER)
505                 goto out;
506
507         /* check if netpoll clients need ARP */
508         if (skb->protocol == htons(ETH_P_ARP) &&
509             atomic_read(&trapped)) {
510                 skb_queue_tail(&npi->arp_tx, skb);
511                 return 1;
512         }
513
514         proto = ntohs(eth_hdr(skb)->h_proto);
515         if (proto != ETH_P_IP)
516                 goto out;
517         if (skb->pkt_type == PACKET_OTHERHOST)
518                 goto out;
519         if (skb_shared(skb))
520                 goto out;
521
522         iph = (struct iphdr *)skb->data;
523         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
524                 goto out;
525         if (iph->ihl < 5 || iph->version != 4)
526                 goto out;
527         if (!pskb_may_pull(skb, iph->ihl*4))
528                 goto out;
529         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
530                 goto out;
531
532         len = ntohs(iph->tot_len);
533         if (skb->len < len || len < iph->ihl*4)
534                 goto out;
535
536         /*
537          * Our transport medium may have padded the buffer out.
538          * Now We trim to the true length of the frame.
539          */
540         if (pskb_trim_rcsum(skb, len))
541                 goto out;
542
543         if (iph->protocol != IPPROTO_UDP)
544                 goto out;
545
546         len -= iph->ihl*4;
547         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
548         ulen = ntohs(uh->len);
549
550         if (ulen != len)
551                 goto out;
552         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
553                 goto out;
554         if (np->local_ip && np->local_ip != iph->daddr)
555                 goto out;
556         if (np->remote_ip && np->remote_ip != iph->saddr)
557                 goto out;
558         if (np->local_port && np->local_port != ntohs(uh->dest))
559                 goto out;
560
561         np->rx_hook(np, ntohs(uh->source),
562                     (char *)(uh+1),
563                     ulen - sizeof(struct udphdr));
564
565         kfree_skb(skb);
566         return 1;
567
568 out:
569         if (atomic_read(&trapped)) {
570                 kfree_skb(skb);
571                 return 1;
572         }
573
574         return 0;
575 }
576
577 void netpoll_print_options(struct netpoll *np)
578 {
579         printk(KERN_INFO "%s: local port %d\n",
580                          np->name, np->local_port);
581         printk(KERN_INFO "%s: local IP %pI4\n",
582                          np->name, &np->local_ip);
583         printk(KERN_INFO "%s: interface %s\n",
584                          np->name, np->dev_name);
585         printk(KERN_INFO "%s: remote port %d\n",
586                          np->name, np->remote_port);
587         printk(KERN_INFO "%s: remote IP %pI4\n",
588                          np->name, &np->remote_ip);
589         printk(KERN_INFO "%s: remote ethernet address %pM\n",
590                          np->name, np->remote_mac);
591 }
592
593 int netpoll_parse_options(struct netpoll *np, char *opt)
594 {
595         char *cur=opt, *delim;
596
597         if (*cur != '@') {
598                 if ((delim = strchr(cur, '@')) == NULL)
599                         goto parse_failed;
600                 *delim = 0;
601                 np->local_port = simple_strtol(cur, NULL, 10);
602                 cur = delim;
603         }
604         cur++;
605
606         if (*cur != '/') {
607                 if ((delim = strchr(cur, '/')) == NULL)
608                         goto parse_failed;
609                 *delim = 0;
610                 np->local_ip = in_aton(cur);
611                 cur = delim;
612         }
613         cur++;
614
615         if (*cur != ',') {
616                 /* parse out dev name */
617                 if ((delim = strchr(cur, ',')) == NULL)
618                         goto parse_failed;
619                 *delim = 0;
620                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
621                 cur = delim;
622         }
623         cur++;
624
625         if (*cur != '@') {
626                 /* dst port */
627                 if ((delim = strchr(cur, '@')) == NULL)
628                         goto parse_failed;
629                 *delim = 0;
630                 np->remote_port = simple_strtol(cur, NULL, 10);
631                 cur = delim;
632         }
633         cur++;
634
635         /* dst ip */
636         if ((delim = strchr(cur, '/')) == NULL)
637                 goto parse_failed;
638         *delim = 0;
639         np->remote_ip = in_aton(cur);
640         cur = delim + 1;
641
642         if (*cur != 0) {
643                 /* MAC address */
644                 if ((delim = strchr(cur, ':')) == NULL)
645                         goto parse_failed;
646                 *delim = 0;
647                 np->remote_mac[0] = simple_strtol(cur, NULL, 16);
648                 cur = delim + 1;
649                 if ((delim = strchr(cur, ':')) == NULL)
650                         goto parse_failed;
651                 *delim = 0;
652                 np->remote_mac[1] = simple_strtol(cur, NULL, 16);
653                 cur = delim + 1;
654                 if ((delim = strchr(cur, ':')) == NULL)
655                         goto parse_failed;
656                 *delim = 0;
657                 np->remote_mac[2] = simple_strtol(cur, NULL, 16);
658                 cur = delim + 1;
659                 if ((delim = strchr(cur, ':')) == NULL)
660                         goto parse_failed;
661                 *delim = 0;
662                 np->remote_mac[3] = simple_strtol(cur, NULL, 16);
663                 cur = delim + 1;
664                 if ((delim = strchr(cur, ':')) == NULL)
665                         goto parse_failed;
666                 *delim = 0;
667                 np->remote_mac[4] = simple_strtol(cur, NULL, 16);
668                 cur = delim + 1;
669                 np->remote_mac[5] = simple_strtol(cur, NULL, 16);
670         }
671
672         netpoll_print_options(np);
673
674         return 0;
675
676  parse_failed:
677         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
678                np->name, cur);
679         return -1;
680 }
681
682 int netpoll_setup(struct netpoll *np)
683 {
684         struct net_device *ndev = NULL;
685         struct in_device *in_dev;
686         struct netpoll_info *npinfo;
687         unsigned long flags;
688         int err;
689
690         if (np->dev_name)
691                 ndev = dev_get_by_name(&init_net, np->dev_name);
692         if (!ndev) {
693                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
694                        np->name, np->dev_name);
695                 return -ENODEV;
696         }
697
698         np->dev = ndev;
699         if (!ndev->npinfo) {
700                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
701                 if (!npinfo) {
702                         err = -ENOMEM;
703                         goto release;
704                 }
705
706                 npinfo->rx_flags = 0;
707                 npinfo->rx_np = NULL;
708
709                 spin_lock_init(&npinfo->rx_lock);
710                 skb_queue_head_init(&npinfo->arp_tx);
711                 skb_queue_head_init(&npinfo->txq);
712                 INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
713
714                 atomic_set(&npinfo->refcnt, 1);
715         } else {
716                 npinfo = ndev->npinfo;
717                 atomic_inc(&npinfo->refcnt);
718         }
719
720         if (!ndev->netdev_ops->ndo_poll_controller) {
721                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
722                        np->name, np->dev_name);
723                 err = -ENOTSUPP;
724                 goto release;
725         }
726
727         if (!netif_running(ndev)) {
728                 unsigned long atmost, atleast;
729
730                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
731                        np->name, np->dev_name);
732
733                 rtnl_lock();
734                 err = dev_open(ndev);
735                 rtnl_unlock();
736
737                 if (err) {
738                         printk(KERN_ERR "%s: failed to open %s\n",
739                                np->name, ndev->name);
740                         goto release;
741                 }
742
743                 atleast = jiffies + HZ/10;
744                 atmost = jiffies + carrier_timeout * HZ;
745                 while (!netif_carrier_ok(ndev)) {
746                         if (time_after(jiffies, atmost)) {
747                                 printk(KERN_NOTICE
748                                        "%s: timeout waiting for carrier\n",
749                                        np->name);
750                                 break;
751                         }
752                         msleep(1);
753                 }
754
755                 /* If carrier appears to come up instantly, we don't
756                  * trust it and pause so that we don't pump all our
757                  * queued console messages into the bitbucket.
758                  */
759
760                 if (time_before(jiffies, atleast)) {
761                         printk(KERN_NOTICE "%s: carrier detect appears"
762                                " untrustworthy, waiting 4 seconds\n",
763                                np->name);
764                         msleep(4000);
765                 }
766         }
767
768         if (!np->local_ip) {
769                 rcu_read_lock();
770                 in_dev = __in_dev_get_rcu(ndev);
771
772                 if (!in_dev || !in_dev->ifa_list) {
773                         rcu_read_unlock();
774                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
775                                np->name, np->dev_name);
776                         err = -EDESTADDRREQ;
777                         goto release;
778                 }
779
780                 np->local_ip = in_dev->ifa_list->ifa_local;
781                 rcu_read_unlock();
782                 printk(KERN_INFO "%s: local IP %pI4\n", np->name, &np->local_ip);
783         }
784
785         if (np->rx_hook) {
786                 spin_lock_irqsave(&npinfo->rx_lock, flags);
787                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
788                 npinfo->rx_np = np;
789                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
790         }
791
792         /* fill up the skb queue */
793         refill_skbs();
794
795         /* last thing to do is link it to the net device structure */
796         ndev->npinfo = npinfo;
797
798         /* avoid racing with NAPI reading npinfo */
799         synchronize_rcu();
800
801         return 0;
802
803  release:
804         if (!ndev->npinfo)
805                 kfree(npinfo);
806         np->dev = NULL;
807         dev_put(ndev);
808         return err;
809 }
810
811 static int __init netpoll_init(void)
812 {
813         skb_queue_head_init(&skb_pool);
814         return 0;
815 }
816 core_initcall(netpoll_init);
817
818 void netpoll_cleanup(struct netpoll *np)
819 {
820         struct netpoll_info *npinfo;
821         unsigned long flags;
822
823         if (np->dev) {
824                 npinfo = np->dev->npinfo;
825                 if (npinfo) {
826                         if (npinfo->rx_np == np) {
827                                 spin_lock_irqsave(&npinfo->rx_lock, flags);
828                                 npinfo->rx_np = NULL;
829                                 npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
830                                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
831                         }
832
833                         if (atomic_dec_and_test(&npinfo->refcnt)) {
834                                 skb_queue_purge(&npinfo->arp_tx);
835                                 skb_queue_purge(&npinfo->txq);
836                                 cancel_rearming_delayed_work(&npinfo->tx_work);
837
838                                 /* clean after last, unfinished work */
839                                 __skb_queue_purge(&npinfo->txq);
840                                 kfree(npinfo);
841                                 np->dev->npinfo = NULL;
842                         }
843                 }
844
845                 dev_put(np->dev);
846         }
847
848         np->dev = NULL;
849 }
850
851 int netpoll_trap(void)
852 {
853         return atomic_read(&trapped);
854 }
855
856 void netpoll_set_trap(int trap)
857 {
858         if (trap)
859                 atomic_inc(&trapped);
860         else
861                 atomic_dec(&trapped);
862 }
863
864 EXPORT_SYMBOL(netpoll_set_trap);
865 EXPORT_SYMBOL(netpoll_trap);
866 EXPORT_SYMBOL(netpoll_print_options);
867 EXPORT_SYMBOL(netpoll_parse_options);
868 EXPORT_SYMBOL(netpoll_setup);
869 EXPORT_SYMBOL(netpoll_cleanup);
870 EXPORT_SYMBOL(netpoll_send_udp);
871 EXPORT_SYMBOL(netpoll_poll);