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