netpoll.c revision 0953864160bdd28dfe45fd46fa462b4d2d53cb96 
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
62		if (!netif_device_present(dev) || !netif_running(dev)) {
63			__kfree_skb(skb);
64			continue;
65		}
66
67		local_irq_save(flags);
68		netif_tx_lock(dev);
69		if ((netif_queue_stopped(dev) ||
70		     netif_subqueue_stopped(dev, skb)) ||
71		     dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
72			skb_queue_head(&npinfo->txq, skb);
73			netif_tx_unlock(dev);
74			local_irq_restore(flags);
75
76			schedule_delayed_work(&npinfo->tx_work, HZ/10);
77			return;
78		}
79		netif_tx_unlock(dev);
80		local_irq_restore(flags);
81	}
82}
83
84static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
85			    unsigned short ulen, __be32 saddr, __be32 daddr)
86{
87	__wsum psum;
88
89	if (uh->check == 0 || skb_csum_unnecessary(skb))
90		return 0;
91
92	psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
93
94	if (skb->ip_summed == CHECKSUM_COMPLETE &&
95	    !csum_fold(csum_add(psum, skb->csum)))
96		return 0;
97
98	skb->csum = psum;
99
100	return __skb_checksum_complete(skb);
101}
102
103/*
104 * Check whether delayed processing was scheduled for our NIC. If so,
105 * we attempt to grab the poll lock and use ->poll() to pump the card.
106 * If this fails, either we've recursed in ->poll() or it's already
107 * running on another CPU.
108 *
109 * Note: we don't mask interrupts with this lock because we're using
110 * trylock here and interrupts are already disabled in the softirq
111 * case. Further, we test the poll_owner to avoid recursion on UP
112 * systems where the lock doesn't exist.
113 *
114 * In cases where there is bi-directional communications, reading only
115 * one message at a time can lead to packets being dropped by the
116 * network adapter, forcing superfluous retries and possibly timeouts.
117 * Thus, we set our budget to greater than 1.
118 */
119static int poll_one_napi(struct netpoll_info *npinfo,
120			 struct napi_struct *napi, int budget)
121{
122	int work;
123
124	/* net_rx_action's ->poll() invocations and our's are
125	 * synchronized by this test which is only made while
126	 * holding the napi->poll_lock.
127	 */
128	if (!test_bit(NAPI_STATE_SCHED, &napi->state))
129		return budget;
130
131	npinfo->rx_flags |= NETPOLL_RX_DROP;
132	atomic_inc(&trapped);
133
134	work = napi->poll(napi, budget);
135
136	atomic_dec(&trapped);
137	npinfo->rx_flags &= ~NETPOLL_RX_DROP;
138
139	return budget - work;
140}
141
142static void poll_napi(struct net_device *dev)
143{
144	struct napi_struct *napi;
145	int budget = 16;
146
147	list_for_each_entry(napi, &dev->napi_list, dev_list) {
148		if (napi->poll_owner != smp_processor_id() &&
149		    spin_trylock(&napi->poll_lock)) {
150			budget = poll_one_napi(dev->npinfo, napi, budget);
151			spin_unlock(&napi->poll_lock);
152
153			if (!budget)
154				break;
155		}
156	}
157}
158
159static void service_arp_queue(struct netpoll_info *npi)
160{
161	if (npi) {
162		struct sk_buff *skb;
163
164		while ((skb = skb_dequeue(&npi->arp_tx)))
165			arp_reply(skb);
166	}
167}
168
169void netpoll_poll(struct netpoll *np)
170{
171	struct net_device *dev = np->dev;
172
173	if (!dev || !netif_running(dev) || !dev->poll_controller)
174		return;
175
176	/* Process pending work on NIC */
177	dev->poll_controller(dev);
178
179	poll_napi(dev);
180
181	service_arp_queue(dev->npinfo);
182
183	zap_completion_queue();
184}
185
186static void refill_skbs(void)
187{
188	struct sk_buff *skb;
189	unsigned long flags;
190
191	spin_lock_irqsave(&skb_pool.lock, flags);
192	while (skb_pool.qlen < MAX_SKBS) {
193		skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
194		if (!skb)
195			break;
196
197		__skb_queue_tail(&skb_pool, skb);
198	}
199	spin_unlock_irqrestore(&skb_pool.lock, flags);
200}
201
202static void zap_completion_queue(void)
203{
204	unsigned long flags;
205	struct softnet_data *sd = &get_cpu_var(softnet_data);
206
207	if (sd->completion_queue) {
208		struct sk_buff *clist;
209
210		local_irq_save(flags);
211		clist = sd->completion_queue;
212		sd->completion_queue = NULL;
213		local_irq_restore(flags);
214
215		while (clist != NULL) {
216			struct sk_buff *skb = clist;
217			clist = clist->next;
218			if (skb->destructor)
219				dev_kfree_skb_any(skb); /* put this one back */
220			else
221				__kfree_skb(skb);
222		}
223	}
224
225	put_cpu_var(softnet_data);
226}
227
228static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
229{
230	int count = 0;
231	struct sk_buff *skb;
232
233	zap_completion_queue();
234	refill_skbs();
235repeat:
236
237	skb = alloc_skb(len, GFP_ATOMIC);
238	if (!skb)
239		skb = skb_dequeue(&skb_pool);
240
241	if (!skb) {
242		if (++count < 10) {
243			netpoll_poll(np);
244			goto repeat;
245		}
246		return NULL;
247	}
248
249	atomic_set(&skb->users, 1);
250	skb_reserve(skb, reserve);
251	return skb;
252}
253
254static int netpoll_owner_active(struct net_device *dev)
255{
256	struct napi_struct *napi;
257
258	list_for_each_entry(napi, &dev->napi_list, dev_list) {
259		if (napi->poll_owner == smp_processor_id())
260			return 1;
261	}
262	return 0;
263}
264
265static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
266{
267	int status = NETDEV_TX_BUSY;
268	unsigned long tries;
269	struct net_device *dev = np->dev;
270	struct netpoll_info *npinfo = np->dev->npinfo;
271
272	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
273		__kfree_skb(skb);
274		return;
275	}
276
277	/* don't get messages out of order, and no recursion */
278	if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
279		unsigned long flags;
280
281		local_irq_save(flags);
282		/* try until next clock tick */
283		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
284		     tries > 0; --tries) {
285			if (netif_tx_trylock(dev)) {
286				if (!netif_queue_stopped(dev) &&
287				    !netif_subqueue_stopped(dev, skb))
288					status = dev->hard_start_xmit(skb, dev);
289				netif_tx_unlock(dev);
290
291				if (status == NETDEV_TX_OK)
292					break;
293
294			}
295
296			/* tickle device maybe there is some cleanup */
297			netpoll_poll(np);
298
299			udelay(USEC_PER_POLL);
300		}
301		local_irq_restore(flags);
302	}
303
304	if (status != NETDEV_TX_OK) {
305		skb_queue_tail(&npinfo->txq, skb);
306		schedule_delayed_work(&npinfo->tx_work,0);
307	}
308}
309
310void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
311{
312	int total_len, eth_len, ip_len, udp_len;
313	struct sk_buff *skb;
314	struct udphdr *udph;
315	struct iphdr *iph;
316	struct ethhdr *eth;
317
318	udp_len = len + sizeof(*udph);
319	ip_len = eth_len = udp_len + sizeof(*iph);
320	total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
321
322	skb = find_skb(np, total_len, total_len - len);
323	if (!skb)
324		return;
325
326	skb_copy_to_linear_data(skb, msg, len);
327	skb->len += len;
328
329	skb_push(skb, sizeof(*udph));
330	skb_reset_transport_header(skb);
331	udph = udp_hdr(skb);
332	udph->source = htons(np->local_port);
333	udph->dest = htons(np->remote_port);
334	udph->len = htons(udp_len);
335	udph->check = 0;
336	udph->check = csum_tcpudp_magic(htonl(np->local_ip),
337					htonl(np->remote_ip),
338					udp_len, IPPROTO_UDP,
339					csum_partial((unsigned char *)udph, udp_len, 0));
340	if (udph->check == 0)
341		udph->check = CSUM_MANGLED_0;
342
343	skb_push(skb, sizeof(*iph));
344	skb_reset_network_header(skb);
345	iph = ip_hdr(skb);
346
347	/* iph->version = 4; iph->ihl = 5; */
348	put_unaligned(0x45, (unsigned char *)iph);
349	iph->tos      = 0;
350	put_unaligned(htons(ip_len), &(iph->tot_len));
351	iph->id       = 0;
352	iph->frag_off = 0;
353	iph->ttl      = 64;
354	iph->protocol = IPPROTO_UDP;
355	iph->check    = 0;
356	put_unaligned(htonl(np->local_ip), &(iph->saddr));
357	put_unaligned(htonl(np->remote_ip), &(iph->daddr));
358	iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
359
360	eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
361	skb_reset_mac_header(skb);
362	skb->protocol = eth->h_proto = htons(ETH_P_IP);
363	memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
364	memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
365
366	skb->dev = np->dev;
367
368	netpoll_send_skb(np, skb);
369}
370
371static void arp_reply(struct sk_buff *skb)
372{
373	struct netpoll_info *npinfo = skb->dev->npinfo;
374	struct arphdr *arp;
375	unsigned char *arp_ptr;
376	int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
377	__be32 sip, tip;
378	unsigned char *sha;
379	struct sk_buff *send_skb;
380	struct netpoll *np = NULL;
381
382	if (npinfo->rx_np && npinfo->rx_np->dev == skb->dev)
383		np = npinfo->rx_np;
384	if (!np)
385		return;
386
387	/* No arp on this interface */
388	if (skb->dev->flags & IFF_NOARP)
389		return;
390
391	if (!pskb_may_pull(skb, (sizeof(struct arphdr) +
392				 (2 * skb->dev->addr_len) +
393				 (2 * sizeof(u32)))))
394		return;
395
396	skb_reset_network_header(skb);
397	skb_reset_transport_header(skb);
398	arp = arp_hdr(skb);
399
400	if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
401	     arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
402	    arp->ar_pro != htons(ETH_P_IP) ||
403	    arp->ar_op != htons(ARPOP_REQUEST))
404		return;
405
406	arp_ptr = (unsigned char *)(arp+1);
407	/* save the location of the src hw addr */
408	sha = arp_ptr;
409	arp_ptr += skb->dev->addr_len;
410	memcpy(&sip, arp_ptr, 4);
411	arp_ptr += 4;
412	/* if we actually cared about dst hw addr, it would get copied here */
413	arp_ptr += skb->dev->addr_len;
414	memcpy(&tip, arp_ptr, 4);
415
416	/* Should we ignore arp? */
417	if (tip != htonl(np->local_ip) || LOOPBACK(tip) || MULTICAST(tip))
418		return;
419
420	size = sizeof(struct arphdr) + 2 * (skb->dev->addr_len + 4);
421	send_skb = find_skb(np, size + LL_RESERVED_SPACE(np->dev),
422			    LL_RESERVED_SPACE(np->dev));
423
424	if (!send_skb)
425		return;
426
427	skb_reset_network_header(send_skb);
428	arp = (struct arphdr *) skb_put(send_skb, size);
429	send_skb->dev = skb->dev;
430	send_skb->protocol = htons(ETH_P_ARP);
431
432	/* Fill the device header for the ARP frame */
433	if (dev_hard_header(send_skb, skb->dev, ptype,
434			    sha, np->dev->dev_addr,
435			    send_skb->len) < 0) {
436		kfree_skb(send_skb);
437		return;
438	}
439
440	/*
441	 * Fill out the arp protocol part.
442	 *
443	 * we only support ethernet device type,
444	 * which (according to RFC 1390) should always equal 1 (Ethernet).
445	 */
446
447	arp->ar_hrd = htons(np->dev->type);
448	arp->ar_pro = htons(ETH_P_IP);
449	arp->ar_hln = np->dev->addr_len;
450	arp->ar_pln = 4;
451	arp->ar_op = htons(type);
452
453	arp_ptr=(unsigned char *)(arp + 1);
454	memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
455	arp_ptr += np->dev->addr_len;
456	memcpy(arp_ptr, &tip, 4);
457	arp_ptr += 4;
458	memcpy(arp_ptr, sha, np->dev->addr_len);
459	arp_ptr += np->dev->addr_len;
460	memcpy(arp_ptr, &sip, 4);
461
462	netpoll_send_skb(np, send_skb);
463}
464
465int __netpoll_rx(struct sk_buff *skb)
466{
467	int proto, len, ulen;
468	struct iphdr *iph;
469	struct udphdr *uh;
470	struct netpoll_info *npi = skb->dev->npinfo;
471	struct netpoll *np = npi->rx_np;
472
473	if (!np)
474		goto out;
475	if (skb->dev->type != ARPHRD_ETHER)
476		goto out;
477
478	/* check if netpoll clients need ARP */
479	if (skb->protocol == htons(ETH_P_ARP) &&
480	    atomic_read(&trapped)) {
481		skb_queue_tail(&npi->arp_tx, skb);
482		return 1;
483	}
484
485	proto = ntohs(eth_hdr(skb)->h_proto);
486	if (proto != ETH_P_IP)
487		goto out;
488	if (skb->pkt_type == PACKET_OTHERHOST)
489		goto out;
490	if (skb_shared(skb))
491		goto out;
492
493	iph = (struct iphdr *)skb->data;
494	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
495		goto out;
496	if (iph->ihl < 5 || iph->version != 4)
497		goto out;
498	if (!pskb_may_pull(skb, iph->ihl*4))
499		goto out;
500	if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
501		goto out;
502
503	len = ntohs(iph->tot_len);
504	if (skb->len < len || len < iph->ihl*4)
505		goto out;
506
507	/*
508	 * Our transport medium may have padded the buffer out.
509	 * Now We trim to the true length of the frame.
510	 */
511	if (pskb_trim_rcsum(skb, len))
512		goto out;
513
514	if (iph->protocol != IPPROTO_UDP)
515		goto out;
516
517	len -= iph->ihl*4;
518	uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
519	ulen = ntohs(uh->len);
520
521	if (ulen != len)
522		goto out;
523	if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
524		goto out;
525	if (np->local_ip && np->local_ip != ntohl(iph->daddr))
526		goto out;
527	if (np->remote_ip && np->remote_ip != ntohl(iph->saddr))
528		goto out;
529	if (np->local_port && np->local_port != ntohs(uh->dest))
530		goto out;
531
532	np->rx_hook(np, ntohs(uh->source),
533		    (char *)(uh+1),
534		    ulen - sizeof(struct udphdr));
535
536	kfree_skb(skb);
537	return 1;
538
539out:
540	if (atomic_read(&trapped)) {
541		kfree_skb(skb);
542		return 1;
543	}
544
545	return 0;
546}
547
548void netpoll_print_options(struct netpoll *np)
549{
550	DECLARE_MAC_BUF(mac);
551	printk(KERN_INFO "%s: local port %d\n",
552			 np->name, np->local_port);
553	printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
554			 np->name, HIPQUAD(np->local_ip));
555	printk(KERN_INFO "%s: interface %s\n",
556			 np->name, np->dev_name);
557	printk(KERN_INFO "%s: remote port %d\n",
558			 np->name, np->remote_port);
559	printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
560			 np->name, HIPQUAD(np->remote_ip));
561	printk(KERN_INFO "%s: remote ethernet address %s\n",
562	                 np->name, print_mac(mac, np->remote_mac));
563}
564
565int netpoll_parse_options(struct netpoll *np, char *opt)
566{
567	char *cur=opt, *delim;
568
569	if (*cur != '@') {
570		if ((delim = strchr(cur, '@')) == NULL)
571			goto parse_failed;
572		*delim = 0;
573		np->local_port = simple_strtol(cur, NULL, 10);
574		cur = delim;
575	}
576	cur++;
577
578	if (*cur != '/') {
579		if ((delim = strchr(cur, '/')) == NULL)
580			goto parse_failed;
581		*delim = 0;
582		np->local_ip = ntohl(in_aton(cur));
583		cur = delim;
584	}
585	cur++;
586
587	if (*cur != ',') {
588		/* parse out dev name */
589		if ((delim = strchr(cur, ',')) == NULL)
590			goto parse_failed;
591		*delim = 0;
592		strlcpy(np->dev_name, cur, sizeof(np->dev_name));
593		cur = delim;
594	}
595	cur++;
596
597	if (*cur != '@') {
598		/* dst port */
599		if ((delim = strchr(cur, '@')) == NULL)
600			goto parse_failed;
601		*delim = 0;
602		np->remote_port = simple_strtol(cur, NULL, 10);
603		cur = delim;
604	}
605	cur++;
606
607	/* dst ip */
608	if ((delim = strchr(cur, '/')) == NULL)
609		goto parse_failed;
610	*delim = 0;
611	np->remote_ip = ntohl(in_aton(cur));
612	cur = delim + 1;
613
614	if (*cur != 0) {
615		/* MAC address */
616		if ((delim = strchr(cur, ':')) == NULL)
617			goto parse_failed;
618		*delim = 0;
619		np->remote_mac[0] = simple_strtol(cur, NULL, 16);
620		cur = delim + 1;
621		if ((delim = strchr(cur, ':')) == NULL)
622			goto parse_failed;
623		*delim = 0;
624		np->remote_mac[1] = 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[2] = 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[3] = 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[4] = simple_strtol(cur, NULL, 16);
640		cur = delim + 1;
641		np->remote_mac[5] = simple_strtol(cur, NULL, 16);
642	}
643
644	netpoll_print_options(np);
645
646	return 0;
647
648 parse_failed:
649	printk(KERN_INFO "%s: couldn't parse config at %s!\n",
650	       np->name, cur);
651	return -1;
652}
653
654int netpoll_setup(struct netpoll *np)
655{
656	struct net_device *ndev = NULL;
657	struct in_device *in_dev;
658	struct netpoll_info *npinfo;
659	unsigned long flags;
660	int err;
661
662	if (np->dev_name)
663		ndev = dev_get_by_name(&init_net, np->dev_name);
664	if (!ndev) {
665		printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
666		       np->name, np->dev_name);
667		return -ENODEV;
668	}
669
670	np->dev = ndev;
671	if (!ndev->npinfo) {
672		npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
673		if (!npinfo) {
674			err = -ENOMEM;
675			goto release;
676		}
677
678		npinfo->rx_flags = 0;
679		npinfo->rx_np = NULL;
680
681		spin_lock_init(&npinfo->rx_lock);
682		skb_queue_head_init(&npinfo->arp_tx);
683		skb_queue_head_init(&npinfo->txq);
684		INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
685
686		atomic_set(&npinfo->refcnt, 1);
687	} else {
688		npinfo = ndev->npinfo;
689		atomic_inc(&npinfo->refcnt);
690	}
691
692	if (!ndev->poll_controller) {
693		printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
694		       np->name, np->dev_name);
695		err = -ENOTSUPP;
696		goto release;
697	}
698
699	if (!netif_running(ndev)) {
700		unsigned long atmost, atleast;
701
702		printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
703		       np->name, np->dev_name);
704
705		rtnl_lock();
706		err = dev_open(ndev);
707		rtnl_unlock();
708
709		if (err) {
710			printk(KERN_ERR "%s: failed to open %s\n",
711			       np->name, ndev->name);
712			goto release;
713		}
714
715		atleast = jiffies + HZ/10;
716		atmost = jiffies + 4*HZ;
717		while (!netif_carrier_ok(ndev)) {
718			if (time_after(jiffies, atmost)) {
719				printk(KERN_NOTICE
720				       "%s: timeout waiting for carrier\n",
721				       np->name);
722				break;
723			}
724			cond_resched();
725		}
726
727		/* If carrier appears to come up instantly, we don't
728		 * trust it and pause so that we don't pump all our
729		 * queued console messages into the bitbucket.
730		 */
731
732		if (time_before(jiffies, atleast)) {
733			printk(KERN_NOTICE "%s: carrier detect appears"
734			       " untrustworthy, waiting 4 seconds\n",
735			       np->name);
736			msleep(4000);
737		}
738	}
739
740	if (!np->local_ip) {
741		rcu_read_lock();
742		in_dev = __in_dev_get_rcu(ndev);
743
744		if (!in_dev || !in_dev->ifa_list) {
745			rcu_read_unlock();
746			printk(KERN_ERR "%s: no IP address for %s, aborting\n",
747			       np->name, np->dev_name);
748			err = -EDESTADDRREQ;
749			goto release;
750		}
751
752		np->local_ip = ntohl(in_dev->ifa_list->ifa_local);
753		rcu_read_unlock();
754		printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
755		       np->name, HIPQUAD(np->local_ip));
756	}
757
758	if (np->rx_hook) {
759		spin_lock_irqsave(&npinfo->rx_lock, flags);
760		npinfo->rx_flags |= NETPOLL_RX_ENABLED;
761		npinfo->rx_np = np;
762		spin_unlock_irqrestore(&npinfo->rx_lock, flags);
763	}
764
765	/* fill up the skb queue */
766	refill_skbs();
767
768	/* last thing to do is link it to the net device structure */
769	ndev->npinfo = npinfo;
770
771	/* avoid racing with NAPI reading npinfo */
772	synchronize_rcu();
773
774	return 0;
775
776 release:
777	if (!ndev->npinfo)
778		kfree(npinfo);
779	np->dev = NULL;
780	dev_put(ndev);
781	return err;
782}
783
784static int __init netpoll_init(void)
785{
786	skb_queue_head_init(&skb_pool);
787	return 0;
788}
789core_initcall(netpoll_init);
790
791void netpoll_cleanup(struct netpoll *np)
792{
793	struct netpoll_info *npinfo;
794	unsigned long flags;
795
796	if (np->dev) {
797		npinfo = np->dev->npinfo;
798		if (npinfo) {
799			if (npinfo->rx_np == np) {
800				spin_lock_irqsave(&npinfo->rx_lock, flags);
801				npinfo->rx_np = NULL;
802				npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
803				spin_unlock_irqrestore(&npinfo->rx_lock, flags);
804			}
805
806			if (atomic_dec_and_test(&npinfo->refcnt)) {
807				skb_queue_purge(&npinfo->arp_tx);
808				skb_queue_purge(&npinfo->txq);
809				cancel_rearming_delayed_work(&npinfo->tx_work);
810
811				/* clean after last, unfinished work */
812				__skb_queue_purge(&npinfo->txq);
813				kfree(npinfo);
814				np->dev->npinfo = NULL;
815			}
816		}
817
818		dev_put(np->dev);
819	}
820
821	np->dev = NULL;
822}
823
824int netpoll_trap(void)
825{
826	return atomic_read(&trapped);
827}
828
829void netpoll_set_trap(int trap)
830{
831	if (trap)
832		atomic_inc(&trapped);
833	else
834		atomic_dec(&trapped);
835}
836
837EXPORT_SYMBOL(netpoll_set_trap);
838EXPORT_SYMBOL(netpoll_trap);
839EXPORT_SYMBOL(netpoll_print_options);
840EXPORT_SYMBOL(netpoll_parse_options);
841EXPORT_SYMBOL(netpoll_setup);
842EXPORT_SYMBOL(netpoll_cleanup);
843EXPORT_SYMBOL(netpoll_send_udp);
844EXPORT_SYMBOL(netpoll_poll);
845