netpoll.c revision fd2ea0a79faad824258af5dcec1927aa24d81c16 
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
37static struct sk_buff_head skb_pool;
38
39static 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
49static void zap_completion_queue(void);
50static void arp_reply(struct sk_buff *skb);
51
52static void queue_process(struct work_struct *work)
53{
54	struct netpoll_info *npinfo =
55		container_of(work, struct netpoll_info, tx_work.work);
56	struct sk_buff *skb;
57	unsigned long flags;
58
59	while ((skb = skb_dequeue(&npinfo->txq))) {
60		struct net_device *dev = skb->dev;
61		struct netdev_queue *txq;
62
63		if (!netif_device_present(dev) || !netif_running(dev)) {
64			__kfree_skb(skb);
65			continue;
66		}
67
68		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
69
70		local_irq_save(flags);
71		__netif_tx_lock(txq, smp_processor_id());
72		if (netif_tx_queue_stopped(txq) ||
73		    dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
74			skb_queue_head(&npinfo->txq, skb);
75			__netif_tx_unlock(txq);
76			local_irq_restore(flags);
77
78			schedule_delayed_work(&npinfo->tx_work, HZ/10);
79			return;
80		}
81		__netif_tx_unlock(txq);
82		local_irq_restore(flags);
83	}
84}
85
86static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
87			    unsigned short ulen, __be32 saddr, __be32 daddr)
88{
89	__wsum psum;
90
91	if (uh->check == 0 || skb_csum_unnecessary(skb))
92		return 0;
93
94	psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
95
96	if (skb->ip_summed == CHECKSUM_COMPLETE &&
97	    !csum_fold(csum_add(psum, skb->csum)))
98		return 0;
99
100	skb->csum = psum;
101
102	return __skb_checksum_complete(skb);
103}
104
105/*
106 * Check whether delayed processing was scheduled for our NIC. If so,
107 * we attempt to grab the poll lock and use ->poll() to pump the card.
108 * If this fails, either we've recursed in ->poll() or it's already
109 * running on another CPU.
110 *
111 * Note: we don't mask interrupts with this lock because we're using
112 * trylock here and interrupts are already disabled in the softirq
113 * case. Further, we test the poll_owner to avoid recursion on UP
114 * systems where the lock doesn't exist.
115 *
116 * In cases where there is bi-directional communications, reading only
117 * one message at a time can lead to packets being dropped by the
118 * network adapter, forcing superfluous retries and possibly timeouts.
119 * Thus, we set our budget to greater than 1.
120 */
121static int poll_one_napi(struct netpoll_info *npinfo,
122			 struct napi_struct *napi, int budget)
123{
124	int work;
125
126	/* net_rx_action's ->poll() invocations and our's are
127	 * synchronized by this test which is only made while
128	 * holding the napi->poll_lock.
129	 */
130	if (!test_bit(NAPI_STATE_SCHED, &napi->state))
131		return budget;
132
133	npinfo->rx_flags |= NETPOLL_RX_DROP;
134	atomic_inc(&trapped);
135
136	work = napi->poll(napi, budget);
137
138	atomic_dec(&trapped);
139	npinfo->rx_flags &= ~NETPOLL_RX_DROP;
140
141	return budget - work;
142}
143
144static void poll_napi(struct net_device *dev)
145{
146	struct napi_struct *napi;
147	int budget = 16;
148
149	list_for_each_entry(napi, &dev->napi_list, dev_list) {
150		if (napi->poll_owner != smp_processor_id() &&
151		    spin_trylock(&napi->poll_lock)) {
152			budget = poll_one_napi(dev->npinfo, napi, budget);
153			spin_unlock(&napi->poll_lock);
154
155			if (!budget)
156				break;
157		}
158	}
159}
160
161static void service_arp_queue(struct netpoll_info *npi)
162{
163	if (npi) {
164		struct sk_buff *skb;
165
166		while ((skb = skb_dequeue(&npi->arp_tx)))
167			arp_reply(skb);
168	}
169}
170
171void netpoll_poll(struct netpoll *np)
172{
173	struct net_device *dev = np->dev;
174
175	if (!dev || !netif_running(dev) || !dev->poll_controller)
176		return;
177
178	/* Process pending work on NIC */
179	dev->poll_controller(dev);
180
181	poll_napi(dev);
182
183	service_arp_queue(dev->npinfo);
184
185	zap_completion_queue();
186}
187
188static void refill_skbs(void)
189{
190	struct sk_buff *skb;
191	unsigned long flags;
192
193	spin_lock_irqsave(&skb_pool.lock, flags);
194	while (skb_pool.qlen < MAX_SKBS) {
195		skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
196		if (!skb)
197			break;
198
199		__skb_queue_tail(&skb_pool, skb);
200	}
201	spin_unlock_irqrestore(&skb_pool.lock, flags);
202}
203
204static void zap_completion_queue(void)
205{
206	unsigned long flags;
207	struct softnet_data *sd = &get_cpu_var(softnet_data);
208
209	if (sd->completion_queue) {
210		struct sk_buff *clist;
211
212		local_irq_save(flags);
213		clist = sd->completion_queue;
214		sd->completion_queue = NULL;
215		local_irq_restore(flags);
216
217		while (clist != NULL) {
218			struct sk_buff *skb = clist;
219			clist = clist->next;
220			if (skb->destructor) {
221				atomic_inc(&skb->users);
222				dev_kfree_skb_any(skb); /* put this one back */
223			} else {
224				__kfree_skb(skb);
225			}
226		}
227	}
228
229	put_cpu_var(softnet_data);
230}
231
232static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
233{
234	int count = 0;
235	struct sk_buff *skb;
236
237	zap_completion_queue();
238	refill_skbs();
239repeat:
240
241	skb = alloc_skb(len, GFP_ATOMIC);
242	if (!skb)
243		skb = skb_dequeue(&skb_pool);
244
245	if (!skb) {
246		if (++count < 10) {
247			netpoll_poll(np);
248			goto repeat;
249		}
250		return NULL;
251	}
252
253	atomic_set(&skb->users, 1);
254	skb_reserve(skb, reserve);
255	return skb;
256}
257
258static int netpoll_owner_active(struct net_device *dev)
259{
260	struct napi_struct *napi;
261
262	list_for_each_entry(napi, &dev->napi_list, dev_list) {
263		if (napi->poll_owner == smp_processor_id())
264			return 1;
265	}
266	return 0;
267}
268
269static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
270{
271	int status = NETDEV_TX_BUSY;
272	unsigned long tries;
273	struct net_device *dev = np->dev;
274	struct netpoll_info *npinfo = np->dev->npinfo;
275
276	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
277		__kfree_skb(skb);
278		return;
279	}
280
281	/* don't get messages out of order, and no recursion */
282	if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
283		struct netdev_queue *txq;
284		unsigned long flags;
285
286		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
287
288		local_irq_save(flags);
289		/* try until next clock tick */
290		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
291		     tries > 0; --tries) {
292			if (__netif_tx_trylock(txq)) {
293				if (!netif_tx_queue_stopped(txq))
294					status = dev->hard_start_xmit(skb, dev);
295				__netif_tx_unlock(txq);
296
297				if (status == NETDEV_TX_OK)
298					break;
299
300			}
301
302			/* tickle device maybe there is some cleanup */
303			netpoll_poll(np);
304
305			udelay(USEC_PER_POLL);
306		}
307		local_irq_restore(flags);
308	}
309
310	if (status != NETDEV_TX_OK) {
311		skb_queue_tail(&npinfo->txq, skb);
312		schedule_delayed_work(&npinfo->tx_work,0);
313	}
314}
315
316void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
317{
318	int total_len, eth_len, ip_len, udp_len;
319	struct sk_buff *skb;
320	struct udphdr *udph;
321	struct iphdr *iph;
322	struct ethhdr *eth;
323
324	udp_len = len + sizeof(*udph);
325	ip_len = eth_len = udp_len + sizeof(*iph);
326	total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
327
328	skb = find_skb(np, total_len, total_len - len);
329	if (!skb)
330		return;
331
332	skb_copy_to_linear_data(skb, msg, len);
333	skb->len += len;
334
335	skb_push(skb, sizeof(*udph));
336	skb_reset_transport_header(skb);
337	udph = udp_hdr(skb);
338	udph->source = htons(np->local_port);
339	udph->dest = htons(np->remote_port);
340	udph->len = htons(udp_len);
341	udph->check = 0;
342	udph->check = csum_tcpudp_magic(htonl(np->local_ip),
343					htonl(np->remote_ip),
344					udp_len, IPPROTO_UDP,
345					csum_partial((unsigned char *)udph, udp_len, 0));
346	if (udph->check == 0)
347		udph->check = CSUM_MANGLED_0;
348
349	skb_push(skb, sizeof(*iph));
350	skb_reset_network_header(skb);
351	iph = ip_hdr(skb);
352
353	/* iph->version = 4; iph->ihl = 5; */
354	put_unaligned(0x45, (unsigned char *)iph);
355	iph->tos      = 0;
356	put_unaligned(htons(ip_len), &(iph->tot_len));
357	iph->id       = 0;
358	iph->frag_off = 0;
359	iph->ttl      = 64;
360	iph->protocol = IPPROTO_UDP;
361	iph->check    = 0;
362	put_unaligned(htonl(np->local_ip), &(iph->saddr));
363	put_unaligned(htonl(np->remote_ip), &(iph->daddr));
364	iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
365
366	eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
367	skb_reset_mac_header(skb);
368	skb->protocol = eth->h_proto = htons(ETH_P_IP);
369	memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
370	memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
371
372	skb->dev = np->dev;
373
374	netpoll_send_skb(np, skb);
375}
376
377static void arp_reply(struct sk_buff *skb)
378{
379	struct netpoll_info *npinfo = skb->dev->npinfo;
380	struct arphdr *arp;
381	unsigned char *arp_ptr;
382	int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
383	__be32 sip, tip;
384	unsigned char *sha;
385	struct sk_buff *send_skb;
386	struct netpoll *np = NULL;
387
388	if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
389		np = npinfo->rx_np;
390	if (!np)
391		return;
392
393	/* No arp on this interface */
394	if (skb->dev->flags & IFF_NOARP)
395		return;
396
397	if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
398		return;
399
400	skb_reset_network_header(skb);
401	skb_reset_transport_header(skb);
402	arp = arp_hdr(skb);
403
404	if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
405	     arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
406	    arp->ar_pro != htons(ETH_P_IP) ||
407	    arp->ar_op != htons(ARPOP_REQUEST))
408		return;
409
410	arp_ptr = (unsigned char *)(arp+1);
411	/* save the location of the src hw addr */
412	sha = arp_ptr;
413	arp_ptr += skb->dev->addr_len;
414	memcpy(&sip, arp_ptr, 4);
415	arp_ptr += 4;
416	/* if we actually cared about dst hw addr, it would get copied here */
417	arp_ptr += skb->dev->addr_len;
418	memcpy(&tip, arp_ptr, 4);
419
420	/* Should we ignore arp? */
421	if (tip != htonl(np->local_ip) ||
422	    ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
423		return;
424
425	size = arp_hdr_len(skb->dev);
426	send_skb = find_skb(np, size + LL_ALLOCATED_SPACE(np->dev),
427			    LL_RESERVED_SPACE(np->dev));
428
429	if (!send_skb)
430		return;
431
432	skb_reset_network_header(send_skb);
433	arp = (struct arphdr *) skb_put(send_skb, size);
434	send_skb->dev = skb->dev;
435	send_skb->protocol = htons(ETH_P_ARP);
436
437	/* Fill the device header for the ARP frame */
438	if (dev_hard_header(send_skb, skb->dev, ptype,
439			    sha, np->dev->dev_addr,
440			    send_skb->len) < 0) {
441		kfree_skb(send_skb);
442		return;
443	}
444
445	/*
446	 * Fill out the arp protocol part.
447	 *
448	 * we only support ethernet device type,
449	 * which (according to RFC 1390) should always equal 1 (Ethernet).
450	 */
451
452	arp->ar_hrd = htons(np->dev->type);
453	arp->ar_pro = htons(ETH_P_IP);
454	arp->ar_hln = np->dev->addr_len;
455	arp->ar_pln = 4;
456	arp->ar_op = htons(type);
457
458	arp_ptr=(unsigned char *)(arp + 1);
459	memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
460	arp_ptr += np->dev->addr_len;
461	memcpy(arp_ptr, &tip, 4);
462	arp_ptr += 4;
463	memcpy(arp_ptr, sha, np->dev->addr_len);
464	arp_ptr += np->dev->addr_len;
465	memcpy(arp_ptr, &sip, 4);
466
467	netpoll_send_skb(np, send_skb);
468}
469
470int __netpoll_rx(struct sk_buff *skb)
471{
472	int proto, len, ulen;
473	struct iphdr *iph;
474	struct udphdr *uh;
475	struct netpoll_info *npi = skb->dev->npinfo;
476	struct netpoll *np = npi->rx_np;
477
478	if (!np)
479		goto out;
480	if (skb->dev->type != ARPHRD_ETHER)
481		goto out;
482
483	/* check if netpoll clients need ARP */
484	if (skb->protocol == htons(ETH_P_ARP) &&
485	    atomic_read(&trapped)) {
486		skb_queue_tail(&npi->arp_tx, skb);
487		return 1;
488	}
489
490	proto = ntohs(eth_hdr(skb)->h_proto);
491	if (proto != ETH_P_IP)
492		goto out;
493	if (skb->pkt_type == PACKET_OTHERHOST)
494		goto out;
495	if (skb_shared(skb))
496		goto out;
497
498	iph = (struct iphdr *)skb->data;
499	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
500		goto out;
501	if (iph->ihl < 5 || iph->version != 4)
502		goto out;
503	if (!pskb_may_pull(skb, iph->ihl*4))
504		goto out;
505	if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
506		goto out;
507
508	len = ntohs(iph->tot_len);
509	if (skb->len < len || len < iph->ihl*4)
510		goto out;
511
512	/*
513	 * Our transport medium may have padded the buffer out.
514	 * Now We trim to the true length of the frame.
515	 */
516	if (pskb_trim_rcsum(skb, len))
517		goto out;
518
519	if (iph->protocol != IPPROTO_UDP)
520		goto out;
521
522	len -= iph->ihl*4;
523	uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
524	ulen = ntohs(uh->len);
525
526	if (ulen != len)
527		goto out;
528	if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
529		goto out;
530	if (np->local_ip && np->local_ip != ntohl(iph->daddr))
531		goto out;
532	if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
533		goto out;
534	if (np->local_port && np->local_port != ntohs(uh->dest))
535		goto out;
536
537	np->rx_hook(np, ntohs(uh->source),
538		    (char *)(uh+1),
539		    ulen - sizeof(struct udphdr));
540
541	kfree_skb(skb);
542	return 1;
543
544out:
545	if (atomic_read(&trapped)) {
546		kfree_skb(skb);
547		return 1;
548	}
549
550	return 0;
551}
552
553void netpoll_print_options(struct netpoll *np)
554{
555	DECLARE_MAC_BUF(mac);
556	printk(KERN_INFO "%s: local port %d\n",
557			 np->name, np->local_port);
558	printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
559			 np->name, HIPQUAD(np->local_ip));
560	printk(KERN_INFO "%s: interface %s\n",
561			 np->name, np->dev_name);
562	printk(KERN_INFO "%s: remote port %d\n",
563			 np->name, np->remote_port);
564	printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
565			 np->name, HIPQUAD(np->remote_ip));
566	printk(KERN_INFO "%s: remote ethernet address %s\n",
567	                 np->name, print_mac(mac, np->remote_mac));
568}
569
570int netpoll_parse_options(struct netpoll *np, char *opt)
571{
572	char *cur=opt, *delim;
573
574	if (*cur != '@') {
575		if ((delim = strchr(cur, '@')) == NULL)
576			goto parse_failed;
577		*delim = 0;
578		np->local_port = simple_strtol(cur, NULL, 10);
579		cur = delim;
580	}
581	cur++;
582
583	if (*cur != '/') {
584		if ((delim = strchr(cur, '/')) == NULL)
585			goto parse_failed;
586		*delim = 0;
587		np->local_ip = ntohl(in_aton(cur));
588		cur = delim;
589	}
590	cur++;
591
592	if (*cur != ',') {
593		/* parse out dev name */
594		if ((delim = strchr(cur, ',')) == NULL)
595			goto parse_failed;
596		*delim = 0;
597		strlcpy(np->dev_name, cur, sizeof(np->dev_name));
598		cur = delim;
599	}
600	cur++;
601
602	if (*cur != '@') {
603		/* dst port */
604		if ((delim = strchr(cur, '@')) == NULL)
605			goto parse_failed;
606		*delim = 0;
607		np->remote_port = simple_strtol(cur, NULL, 10);
608		cur = delim;
609	}
610	cur++;
611
612	/* dst ip */
613	if ((delim = strchr(cur, '/')) == NULL)
614		goto parse_failed;
615	*delim = 0;
616	np->remote_ip = ntohl(in_aton(cur));
617	cur = delim + 1;
618
619	if (*cur != 0) {
620		/* MAC address */
621		if ((delim = strchr(cur, ':')) == NULL)
622			goto parse_failed;
623		*delim = 0;
624		np->remote_mac[0] = simple_strtol(cur, NULL, 16);
625		cur = delim + 1;
626		if ((delim = strchr(cur, ':')) == NULL)
627			goto parse_failed;
628		*delim = 0;
629		np->remote_mac[1] = simple_strtol(cur, NULL, 16);
630		cur = delim + 1;
631		if ((delim = strchr(cur, ':')) == NULL)
632			goto parse_failed;
633		*delim = 0;
634		np->remote_mac[2] = simple_strtol(cur, NULL, 16);
635		cur = delim + 1;
636		if ((delim = strchr(cur, ':')) == NULL)
637			goto parse_failed;
638		*delim = 0;
639		np->remote_mac[3] = simple_strtol(cur, NULL, 16);
640		cur = delim + 1;
641		if ((delim = strchr(cur, ':')) == NULL)
642			goto parse_failed;
643		*delim = 0;
644		np->remote_mac[4] = simple_strtol(cur, NULL, 16);
645		cur = delim + 1;
646		np->remote_mac[5] = simple_strtol(cur, NULL, 16);
647	}
648
649	netpoll_print_options(np);
650
651	return 0;
652
653 parse_failed:
654	printk(KERN_INFO "%s: couldn't parse config at %s!\n",
655	       np->name, cur);
656	return -1;
657}
658
659int netpoll_setup(struct netpoll *np)
660{
661	struct net_device *ndev = NULL;
662	struct in_device *in_dev;
663	struct netpoll_info *npinfo;
664	unsigned long flags;
665	int err;
666
667	if (np->dev_name)
668		ndev = dev_get_by_name(&init_net, np->dev_name);
669	if (!ndev) {
670		printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
671		       np->name, np->dev_name);
672		return -ENODEV;
673	}
674
675	np->dev = ndev;
676	if (!ndev->npinfo) {
677		npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
678		if (!npinfo) {
679			err = -ENOMEM;
680			goto release;
681		}
682
683		npinfo->rx_flags = 0;
684		npinfo->rx_np = NULL;
685
686		spin_lock_init(&npinfo->rx_lock);
687		skb_queue_head_init(&npinfo->arp_tx);
688		skb_queue_head_init(&npinfo->txq);
689		INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
690
691		atomic_set(&npinfo->refcnt, 1);
692	} else {
693		npinfo = ndev->npinfo;
694		atomic_inc(&npinfo->refcnt);
695	}
696
697	if (!ndev->poll_controller) {
698		printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
699		       np->name, np->dev_name);
700		err = -ENOTSUPP;
701		goto release;
702	}
703
704	if (!netif_running(ndev)) {
705		unsigned long atmost, atleast;
706
707		printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
708		       np->name, np->dev_name);
709
710		rtnl_lock();
711		err = dev_open(ndev);
712		rtnl_unlock();
713
714		if (err) {
715			printk(KERN_ERR "%s: failed to open %s\n",
716			       np->name, ndev->name);
717			goto release;
718		}
719
720		atleast = jiffies + HZ/10;
721		atmost = jiffies + 4*HZ;
722		while (!netif_carrier_ok(ndev)) {
723			if (time_after(jiffies, atmost)) {
724				printk(KERN_NOTICE
725				       "%s: timeout waiting for carrier\n",
726				       np->name);
727				break;
728			}
729			cond_resched();
730		}
731
732		/* If carrier appears to come up instantly, we don't
733		 * trust it and pause so that we don't pump all our
734		 * queued console messages into the bitbucket.
735		 */
736
737		if (time_before(jiffies, atleast)) {
738			printk(KERN_NOTICE "%s: carrier detect appears"
739			       " untrustworthy, waiting 4 seconds\n",
740			       np->name);
741			msleep(4000);
742		}
743	}
744
745	if (!np->local_ip) {
746		rcu_read_lock();
747		in_dev = __in_dev_get_rcu(ndev);
748
749		if (!in_dev || !in_dev->ifa_list) {
750			rcu_read_unlock();
751			printk(KERN_ERR "%s: no IP address for %s, aborting\n",
752			       np->name, np->dev_name);
753			err = -EDESTADDRREQ;
754			goto release;
755		}
756
757		np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
758		rcu_read_unlock();
759		printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
760		       np->name, HIPQUAD(np->local_ip));
761	}
762
763	if (np->rx_hook) {
764		spin_lock_irqsave(&npinfo->rx_lock, flags);
765		npinfo->rx_flags |= NETPOLL_RX_ENABLED;
766		npinfo->rx_np = np;
767		spin_unlock_irqrestore(&npinfo->rx_lock, flags);
768	}
769
770	/* fill up the skb queue */
771	refill_skbs();
772
773	/* last thing to do is link it to the net device structure */
774	ndev->npinfo = npinfo;
775
776	/* avoid racing with NAPI reading npinfo */
777	synchronize_rcu();
778
779	return 0;
780
781 release:
782	if (!ndev->npinfo)
783		kfree(npinfo);
784	np->dev = NULL;
785	dev_put(ndev);
786	return err;
787}
788
789static int __init netpoll_init(void)
790{
791	skb_queue_head_init(&skb_pool);
792	return 0;
793}
794core_initcall(netpoll_init);
795
796void netpoll_cleanup(struct netpoll *np)
797{
798	struct netpoll_info *npinfo;
799	unsigned long flags;
800
801	if (np->dev) {
802		npinfo = np->dev->npinfo;
803		if (npinfo) {
804			if (npinfo->rx_np == np) {
805				spin_lock_irqsave(&npinfo->rx_lock, flags);
806				npinfo->rx_np = NULL;
807				npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
808				spin_unlock_irqrestore(&npinfo->rx_lock, flags);
809			}
810
811			if (atomic_dec_and_test(&npinfo->refcnt)) {
812				skb_queue_purge(&npinfo->arp_tx);
813				skb_queue_purge(&npinfo->txq);
814				cancel_rearming_delayed_work(&npinfo->tx_work);
815
816				/* clean after last, unfinished work */
817				__skb_queue_purge(&npinfo->txq);
818				kfree(npinfo);
819				np->dev->npinfo = NULL;
820			}
821		}
822
823		dev_put(np->dev);
824	}
825
826	np->dev = NULL;
827}
828
829int netpoll_trap(void)
830{
831	return atomic_read(&trapped);
832}
833
834void netpoll_set_trap(int trap)
835{
836	if (trap)
837		atomic_inc(&trapped);
838	else
839		atomic_dec(&trapped);
840}
841
842EXPORT_SYMBOL(netpoll_set_trap);
843EXPORT_SYMBOL(netpoll_trap);
844EXPORT_SYMBOL(netpoll_print_options);
845EXPORT_SYMBOL(netpoll_parse_options);
846EXPORT_SYMBOL(netpoll_setup);
847EXPORT_SYMBOL(netpoll_cleanup);
848EXPORT_SYMBOL(netpoll_send_udp);
849EXPORT_SYMBOL(netpoll_poll);
850