5265dfd699284a960c5fd95b33a6daf722b1a0bc
[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/smp_lock.h>
13 #include <linux/netdevice.h>
14 #include <linux/etherdevice.h>
15 #include <linux/string.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 #define MAX_RETRIES 20000
37
38 static DEFINE_SPINLOCK(skb_list_lock);
39 static int nr_skbs;
40 static struct sk_buff *skbs;
41
42 static DEFINE_SPINLOCK(queue_lock);
43 static int queue_depth;
44 static struct sk_buff *queue_head, *queue_tail;
45
46 static atomic_t trapped;
47
48 #define NETPOLL_RX_ENABLED  1
49 #define NETPOLL_RX_DROP     2
50
51 #define MAX_SKB_SIZE \
52                 (MAX_UDP_CHUNK + sizeof(struct udphdr) + \
53                                 sizeof(struct iphdr) + sizeof(struct ethhdr))
54
55 static void zap_completion_queue(void);
56
57 static void queue_process(void *p)
58 {
59         unsigned long flags;
60         struct sk_buff *skb;
61
62         while (queue_head) {
63                 spin_lock_irqsave(&queue_lock, flags);
64
65                 skb = queue_head;
66                 queue_head = skb->next;
67                 if (skb == queue_tail)
68                         queue_head = NULL;
69
70                 queue_depth--;
71
72                 spin_unlock_irqrestore(&queue_lock, flags);
73
74                 dev_queue_xmit(skb);
75         }
76 }
77
78 static DECLARE_WORK(send_queue, queue_process, NULL);
79
80 void netpoll_queue(struct sk_buff *skb)
81 {
82         unsigned long flags;
83
84         if (queue_depth == MAX_QUEUE_DEPTH) {
85                 __kfree_skb(skb);
86                 return;
87         }
88
89         spin_lock_irqsave(&queue_lock, flags);
90         if (!queue_head)
91                 queue_head = skb;
92         else
93                 queue_tail->next = skb;
94         queue_tail = skb;
95         queue_depth++;
96         spin_unlock_irqrestore(&queue_lock, flags);
97
98         schedule_work(&send_queue);
99 }
100
101 static int checksum_udp(struct sk_buff *skb, struct udphdr *uh,
102                              unsigned short ulen, u32 saddr, u32 daddr)
103 {
104         if (uh->check == 0)
105                 return 0;
106
107         if (skb->ip_summed == CHECKSUM_HW)
108                 return csum_tcpudp_magic(
109                         saddr, daddr, ulen, IPPROTO_UDP, skb->csum);
110
111         skb->csum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
112
113         return csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));
114 }
115
116 /*
117  * Check whether delayed processing was scheduled for our NIC. If so,
118  * we attempt to grab the poll lock and use ->poll() to pump the card.
119  * If this fails, either we've recursed in ->poll() or it's already
120  * running on another CPU.
121  *
122  * Note: we don't mask interrupts with this lock because we're using
123  * trylock here and interrupts are already disabled in the softirq
124  * case. Further, we test the poll_owner to avoid recursion on UP
125  * systems where the lock doesn't exist.
126  *
127  * In cases where there is bi-directional communications, reading only
128  * one message at a time can lead to packets being dropped by the
129  * network adapter, forcing superfluous retries and possibly timeouts.
130  * Thus, we set our budget to greater than 1.
131  */
132 static void poll_napi(struct netpoll *np)
133 {
134         struct netpoll_info *npinfo = np->dev->npinfo;
135         int budget = 16;
136
137         if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
138             npinfo->poll_owner != smp_processor_id() &&
139             spin_trylock(&npinfo->poll_lock)) {
140                 npinfo->rx_flags |= NETPOLL_RX_DROP;
141                 atomic_inc(&trapped);
142
143                 np->dev->poll(np->dev, &budget);
144
145                 atomic_dec(&trapped);
146                 npinfo->rx_flags &= ~NETPOLL_RX_DROP;
147                 spin_unlock(&npinfo->poll_lock);
148         }
149 }
150
151 void netpoll_poll(struct netpoll *np)
152 {
153         if(!np->dev || !netif_running(np->dev) || !np->dev->poll_controller)
154                 return;
155
156         /* Process pending work on NIC */
157         np->dev->poll_controller(np->dev);
158         if (np->dev->poll)
159                 poll_napi(np);
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_list_lock, flags);
170         while (nr_skbs < MAX_SKBS) {
171                 skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
172                 if (!skb)
173                         break;
174
175                 skb->next = skbs;
176                 skbs = skb;
177                 nr_skbs++;
178         }
179         spin_unlock_irqrestore(&skb_list_lock, flags);
180 }
181
182 static void zap_completion_queue(void)
183 {
184         unsigned long flags;
185         struct softnet_data *sd = &get_cpu_var(softnet_data);
186
187         if (sd->completion_queue) {
188                 struct sk_buff *clist;
189
190                 local_irq_save(flags);
191                 clist = sd->completion_queue;
192                 sd->completion_queue = NULL;
193                 local_irq_restore(flags);
194
195                 while (clist != NULL) {
196                         struct sk_buff *skb = clist;
197                         clist = clist->next;
198                         if(skb->destructor)
199                                 dev_kfree_skb_any(skb); /* put this one back */
200                         else
201                                 __kfree_skb(skb);
202                 }
203         }
204
205         put_cpu_var(softnet_data);
206 }
207
208 static struct sk_buff * find_skb(struct netpoll *np, int len, int reserve)
209 {
210         int once = 1, count = 0;
211         unsigned long flags;
212         struct sk_buff *skb = NULL;
213
214         zap_completion_queue();
215 repeat:
216         if (nr_skbs < MAX_SKBS)
217                 refill_skbs();
218
219         skb = alloc_skb(len, GFP_ATOMIC);
220
221         if (!skb) {
222                 spin_lock_irqsave(&skb_list_lock, flags);
223                 skb = skbs;
224                 if (skb) {
225                         skbs = skb->next;
226                         skb->next = NULL;
227                         nr_skbs--;
228                 }
229                 spin_unlock_irqrestore(&skb_list_lock, flags);
230         }
231
232         if(!skb) {
233                 count++;
234                 if (once && (count == 1000000)) {
235                         printk("out of netpoll skbs!\n");
236                         once = 0;
237                 }
238                 netpoll_poll(np);
239                 goto repeat;
240         }
241
242         atomic_set(&skb->users, 1);
243         skb_reserve(skb, reserve);
244         return skb;
245 }
246
247 static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
248 {
249         int status;
250         struct netpoll_info *npinfo;
251
252         if (!np || !np->dev || !netif_running(np->dev)) {
253                 __kfree_skb(skb);
254                 return;
255         }
256
257         npinfo = np->dev->npinfo;
258
259         /* avoid recursion */
260         if (npinfo->poll_owner == smp_processor_id() ||
261             np->dev->xmit_lock_owner == smp_processor_id()) {
262                 if (np->drop)
263                         np->drop(skb);
264                 else
265                         __kfree_skb(skb);
266                 return;
267         }
268
269         do {
270                 npinfo->tries--;
271                 spin_lock(&np->dev->xmit_lock);
272                 np->dev->xmit_lock_owner = smp_processor_id();
273
274                 /*
275                  * network drivers do not expect to be called if the queue is
276                  * stopped.
277                  */
278                 if (netif_queue_stopped(np->dev)) {
279                         np->dev->xmit_lock_owner = -1;
280                         spin_unlock(&np->dev->xmit_lock);
281                         netpoll_poll(np);
282                         udelay(50);
283                         continue;
284                 }
285
286                 status = np->dev->hard_start_xmit(skb, np->dev);
287                 np->dev->xmit_lock_owner = -1;
288                 spin_unlock(&np->dev->xmit_lock);
289
290                 /* success */
291                 if(!status) {
292                         npinfo->tries = MAX_RETRIES; /* reset */
293                         return;
294                 }
295
296                 /* transmit busy */
297                 netpoll_poll(np);
298                 udelay(50);
299         } while (npinfo->tries > 0);
300 }
301
302 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
303 {
304         int total_len, eth_len, ip_len, udp_len;
305         struct sk_buff *skb;
306         struct udphdr *udph;
307         struct iphdr *iph;
308         struct ethhdr *eth;
309
310         udp_len = len + sizeof(*udph);
311         ip_len = eth_len = udp_len + sizeof(*iph);
312         total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
313
314         skb = find_skb(np, total_len, total_len - len);
315         if (!skb)
316                 return;
317
318         memcpy(skb->data, msg, len);
319         skb->len += len;
320
321         udph = (struct udphdr *) skb_push(skb, sizeof(*udph));
322         udph->source = htons(np->local_port);
323         udph->dest = htons(np->remote_port);
324         udph->len = htons(udp_len);
325         udph->check = 0;
326
327         iph = (struct iphdr *)skb_push(skb, sizeof(*iph));
328
329         /* iph->version = 4; iph->ihl = 5; */
330         put_unaligned(0x45, (unsigned char *)iph);
331         iph->tos      = 0;
332         put_unaligned(htons(ip_len), &(iph->tot_len));
333         iph->id       = 0;
334         iph->frag_off = 0;
335         iph->ttl      = 64;
336         iph->protocol = IPPROTO_UDP;
337         iph->check    = 0;
338         put_unaligned(htonl(np->local_ip), &(iph->saddr));
339         put_unaligned(htonl(np->remote_ip), &(iph->daddr));
340         iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
341
342         eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
343
344         eth->h_proto = htons(ETH_P_IP);
345         memcpy(eth->h_source, np->local_mac, 6);
346         memcpy(eth->h_dest, np->remote_mac, 6);
347
348         skb->dev = np->dev;
349
350         netpoll_send_skb(np, skb);
351 }
352
353 static void arp_reply(struct sk_buff *skb)
354 {
355         struct netpoll_info *npinfo = skb->dev->npinfo;
356         struct arphdr *arp;
357         unsigned char *arp_ptr;
358         int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
359         u32 sip, tip;
360         struct sk_buff *send_skb;
361         struct netpoll *np = NULL;
362
363         if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
364                 np = npinfo->rx_np;
365         if (!np)
366                 return;
367
368         /* No arp on this interface */
369         if (skb->dev->flags & IFF_NOARP)
370                 return;
371
372         if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
373                                  (2 * skb->dev->addr_len) +
374                                  (2 * sizeof(u32)))))
375                 return;
376
377         skb->h.raw = skb->nh.raw = skb->data;
378         arp = skb->nh.arph;
379
380         if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
381              arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
382             arp->ar_pro != htons(ETH_P_IP) ||
383             arp->ar_op != htons(ARPOP_REQUEST))
384                 return;
385
386         arp_ptr = (unsigned char *)(arp+1) + skb->dev->addr_len;
387         memcpy(&sip, arp_ptr, 4);
388         arp_ptr += 4 + skb->dev->addr_len;
389         memcpy(&tip, arp_ptr, 4);
390
391         /* Should we ignore arp? */
392         if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
393                 return;
394
395         size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
396         send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
397                             LL_RESERVED_SPACE(np->dev));
398
399         if (!send_skb)
400                 return;
401
402         send_skb->nh.raw = send_skb->data;
403         arp = (struct arphdr *) skb_put(send_skb, size);
404         send_skb->dev = skb->dev;
405         send_skb->protocol = htons(ETH_P_ARP);
406
407         /* Fill the device header for the ARP frame */
408
409         if (np->dev->hard_header &&
410             np->dev->hard_header(send_skb, skb->dev, ptype,
411                                        np->remote_mac, np->local_mac,
412                                        send_skb->len) < 0) {
413                 kfree_skb(send_skb);
414                 return;
415         }
416
417         /*
418          * Fill out the arp protocol part.
419          *
420          * we only support ethernet device type,
421          * which (according to RFC 1390) should always equal 1 (Ethernet).
422          */
423
424         arp->ar_hrd = htons(np->dev->type);
425         arp->ar_pro = htons(ETH_P_IP);
426         arp->ar_hln = np->dev->addr_len;
427         arp->ar_pln = 4;
428         arp->ar_op = htons(type);
429
430         arp_ptr=(unsigned char *)(arp + 1);
431         memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
432         arp_ptr += np->dev->addr_len;
433         memcpy(arp_ptr, &tip, 4);
434         arp_ptr += 4;
435         memcpy(arp_ptr, np->remote_mac, np->dev->addr_len);
436         arp_ptr += np->dev->addr_len;
437         memcpy(arp_ptr, &sip, 4);
438
439         netpoll_send_skb(np, send_skb);
440 }
441
442 int __netpoll_rx(struct sk_buff *skb)
443 {
444         int proto, len, ulen;
445         struct iphdr *iph;
446         struct udphdr *uh;
447         struct netpoll *np = skb->dev->npinfo->rx_np;
448
449         if (!np)
450                 goto out;
451         if (skb->dev->type != ARPHRD_ETHER)
452                 goto out;
453
454         /* check if netpoll clients need ARP */
455         if (skb->protocol == __constant_htons(ETH_P_ARP) &&
456             atomic_read(&trapped)) {
457                 arp_reply(skb);
458                 return 1;
459         }
460
461         proto = ntohs(eth_hdr(skb)->h_proto);
462         if (proto != ETH_P_IP)
463                 goto out;
464         if (skb->pkt_type == PACKET_OTHERHOST)
465                 goto out;
466         if (skb_shared(skb))
467                 goto out;
468
469         iph = (struct iphdr *)skb->data;
470         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
471                 goto out;
472         if (iph->ihl < 5 || iph->version != 4)
473                 goto out;
474         if (!pskb_may_pull(skb, iph->ihl*4))
475                 goto out;
476         if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
477                 goto out;
478
479         len = ntohs(iph->tot_len);
480         if (skb->len < len || len < iph->ihl*4)
481                 goto out;
482
483         if (iph->protocol != IPPROTO_UDP)
484                 goto out;
485
486         len -= iph->ihl*4;
487         uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
488         ulen = ntohs(uh->len);
489
490         if (ulen != len)
491                 goto out;
492         if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr) < 0)
493                 goto out;
494         if (np->local_ip && np->local_ip != ntohl(iph->daddr))
495                 goto out;
496         if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
497                 goto out;
498         if (np->local_port && np->local_port != ntohs(uh->dest))
499                 goto out;
500
501         np->rx_hook(np, ntohs(uh->source),
502                     (char *)(uh+1),
503                     ulen - sizeof(struct udphdr));
504
505         kfree_skb(skb);
506         return 1;
507
508 out:
509         if (atomic_read(&trapped)) {
510                 kfree_skb(skb);
511                 return 1;
512         }
513
514         return 0;
515 }
516
517 int netpoll_parse_options(struct netpoll *np, char *opt)
518 {
519         char *cur=opt, *delim;
520
521         if(*cur != '@') {
522                 if ((delim = strchr(cur, '@')) == NULL)
523                         goto parse_failed;
524                 *delim=0;
525                 np->local_port=simple_strtol(cur, NULL, 10);
526                 cur=delim;
527         }
528         cur++;
529         printk(KERN_INFO "%s: local port %d\n", np->name, np->local_port);
530
531         if(*cur != '/') {
532                 if ((delim = strchr(cur, '/')) == NULL)
533                         goto parse_failed;
534                 *delim=0;
535                 np->local_ip=ntohl(in_aton(cur));
536                 cur=delim;
537
538                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
539                        np->name, HIPQUAD(np->local_ip));
540         }
541         cur++;
542
543         if ( *cur != ',') {
544                 /* parse out dev name */
545                 if ((delim = strchr(cur, ',')) == NULL)
546                         goto parse_failed;
547                 *delim=0;
548                 strlcpy(np->dev_name, cur, sizeof(np->dev_name));
549                 cur=delim;
550         }
551         cur++;
552
553         printk(KERN_INFO "%s: interface %s\n", np->name, np->dev_name);
554
555         if ( *cur != '@' ) {
556                 /* dst port */
557                 if ((delim = strchr(cur, '@')) == NULL)
558                         goto parse_failed;
559                 *delim=0;
560                 np->remote_port=simple_strtol(cur, NULL, 10);
561                 cur=delim;
562         }
563         cur++;
564         printk(KERN_INFO "%s: remote port %d\n", np->name, np->remote_port);
565
566         /* dst ip */
567         if ((delim = strchr(cur, '/')) == NULL)
568                 goto parse_failed;
569         *delim=0;
570         np->remote_ip=ntohl(in_aton(cur));
571         cur=delim+1;
572
573         printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
574                        np->name, HIPQUAD(np->remote_ip));
575
576         if( *cur != 0 )
577         {
578                 /* MAC address */
579                 if ((delim = strchr(cur, ':')) == NULL)
580                         goto parse_failed;
581                 *delim=0;
582                 np->remote_mac[0]=simple_strtol(cur, NULL, 16);
583                 cur=delim+1;
584                 if ((delim = strchr(cur, ':')) == NULL)
585                         goto parse_failed;
586                 *delim=0;
587                 np->remote_mac[1]=simple_strtol(cur, NULL, 16);
588                 cur=delim+1;
589                 if ((delim = strchr(cur, ':')) == NULL)
590                         goto parse_failed;
591                 *delim=0;
592                 np->remote_mac[2]=simple_strtol(cur, NULL, 16);
593                 cur=delim+1;
594                 if ((delim = strchr(cur, ':')) == NULL)
595                         goto parse_failed;
596                 *delim=0;
597                 np->remote_mac[3]=simple_strtol(cur, NULL, 16);
598                 cur=delim+1;
599                 if ((delim = strchr(cur, ':')) == NULL)
600                         goto parse_failed;
601                 *delim=0;
602                 np->remote_mac[4]=simple_strtol(cur, NULL, 16);
603                 cur=delim+1;
604                 np->remote_mac[5]=simple_strtol(cur, NULL, 16);
605         }
606
607         printk(KERN_INFO "%s: remote ethernet address "
608                "%02x:%02x:%02x:%02x:%02x:%02x\n",
609                np->name,
610                np->remote_mac[0],
611                np->remote_mac[1],
612                np->remote_mac[2],
613                np->remote_mac[3],
614                np->remote_mac[4],
615                np->remote_mac[5]);
616
617         return 0;
618
619  parse_failed:
620         printk(KERN_INFO "%s: couldn't parse config at %s!\n",
621                np->name, cur);
622         return -1;
623 }
624
625 int netpoll_setup(struct netpoll *np)
626 {
627         struct net_device *ndev = NULL;
628         struct in_device *in_dev;
629         struct netpoll_info *npinfo;
630         unsigned long flags;
631
632         if (np->dev_name)
633                 ndev = dev_get_by_name(np->dev_name);
634         if (!ndev) {
635                 printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
636                        np->name, np->dev_name);
637                 return -1;
638         }
639
640         np->dev = ndev;
641         if (!ndev->npinfo) {
642                 npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
643                 if (!npinfo)
644                         goto release;
645
646                 npinfo->rx_flags = 0;
647                 npinfo->rx_np = NULL;
648                 spin_lock_init(&npinfo->poll_lock);
649                 npinfo->poll_owner = -1;
650                 npinfo->tries = MAX_RETRIES;
651                 spin_lock_init(&npinfo->rx_lock);
652         } else
653                 npinfo = ndev->npinfo;
654
655         if (!ndev->poll_controller) {
656                 printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
657                        np->name, np->dev_name);
658                 goto release;
659         }
660
661         if (!netif_running(ndev)) {
662                 unsigned long atmost, atleast;
663
664                 printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
665                        np->name, np->dev_name);
666
667                 rtnl_shlock();
668                 if (dev_change_flags(ndev, ndev->flags | IFF_UP) < 0) {
669                         printk(KERN_ERR "%s: failed to open %s\n",
670                                np->name, np->dev_name);
671                         rtnl_shunlock();
672                         goto release;
673                 }
674                 rtnl_shunlock();
675
676                 atleast = jiffies + HZ/10;
677                 atmost = jiffies + 4*HZ;
678                 while (!netif_carrier_ok(ndev)) {
679                         if (time_after(jiffies, atmost)) {
680                                 printk(KERN_NOTICE
681                                        "%s: timeout waiting for carrier\n",
682                                        np->name);
683                                 break;
684                         }
685                         cond_resched();
686                 }
687
688                 /* If carrier appears to come up instantly, we don't
689                  * trust it and pause so that we don't pump all our
690                  * queued console messages into the bitbucket.
691                  */
692
693                 if (time_before(jiffies, atleast)) {
694                         printk(KERN_NOTICE "%s: carrier detect appears"
695                                " untrustworthy, waiting 4 seconds\n",
696                                np->name);
697                         msleep(4000);
698                 }
699         }
700
701         if (!memcmp(np->local_mac, "\0\0\0\0\0\0", 6) && ndev->dev_addr)
702                 memcpy(np->local_mac, ndev->dev_addr, 6);
703
704         if (!np->local_ip) {
705                 rcu_read_lock();
706                 in_dev = __in_dev_get(ndev);
707
708                 if (!in_dev || !in_dev->ifa_list) {
709                         rcu_read_unlock();
710                         printk(KERN_ERR "%s: no IP address for %s, aborting\n",
711                                np->name, np->dev_name);
712                         goto release;
713                 }
714
715                 np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
716                 rcu_read_unlock();
717                 printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
718                        np->name, HIPQUAD(np->local_ip));
719         }
720
721         if (np->rx_hook) {
722                 spin_lock_irqsave(&npinfo->rx_lock, flags);
723                 npinfo->rx_flags |= NETPOLL_RX_ENABLED;
724                 npinfo->rx_np = np;
725                 spin_unlock_irqrestore(&npinfo->rx_lock, flags);
726         }
727
728         /* fill up the skb queue */
729         refill_skbs();
730
731         /* last thing to do is link it to the net device structure */
732         ndev->npinfo = npinfo;
733
734         /* avoid racing with NAPI reading npinfo */
735         synchronize_rcu();
736
737         return 0;
738
739  release:
740         if (!ndev->npinfo)
741                 kfree(npinfo);
742         np->dev = NULL;
743         dev_put(ndev);
744         return -1;
745 }
746
747 void netpoll_cleanup(struct netpoll *np)
748 {
749         struct netpoll_info *npinfo;
750         unsigned long flags;
751
752         if (np->dev) {
753                 npinfo = np->dev->npinfo;
754                 if (npinfo && npinfo->rx_np == np) {
755                         spin_lock_irqsave(&npinfo->rx_lock, flags);
756                         npinfo->rx_np = NULL;
757                         npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
758                         spin_unlock_irqrestore(&npinfo->rx_lock, flags);
759                 }
760                 dev_put(np->dev);
761         }
762
763         np->dev = NULL;
764 }
765
766 int netpoll_trap(void)
767 {
768         return atomic_read(&trapped);
769 }
770
771 void netpoll_set_trap(int trap)
772 {
773         if (trap)
774                 atomic_inc(&trapped);
775         else
776                 atomic_dec(&trapped);
777 }
778
779 EXPORT_SYMBOL(netpoll_set_trap);
780 EXPORT_SYMBOL(netpoll_trap);
781 EXPORT_SYMBOL(netpoll_parse_options);
782 EXPORT_SYMBOL(netpoll_setup);
783 EXPORT_SYMBOL(netpoll_cleanup);
784 EXPORT_SYMBOL(netpoll_send_udp);
785 EXPORT_SYMBOL(netpoll_poll);
786 EXPORT_SYMBOL(netpoll_queue);