netpoll.c revision a9b3cd7f323b2e57593e7215362a7b02fc933e3a 
1/*
2 * Common framework for low-level network console, dump, and debugger code
3 *
4 * Sep 8 2003  Matt Mackall <mpm@selenic.com>
5 *
6 * based on the netconsole code from:
7 *
8 * Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
9 * Copyright (C) 2002  Red Hat, Inc.
10 */
11
12#include <linux/moduleparam.h>
13#include <linux/netdevice.h>
14#include <linux/etherdevice.h>
15#include <linux/string.h>
16#include <linux/if_arp.h>
17#include <linux/inetdevice.h>
18#include <linux/inet.h>
19#include <linux/interrupt.h>
20#include <linux/netpoll.h>
21#include <linux/sched.h>
22#include <linux/delay.h>
23#include <linux/rcupdate.h>
24#include <linux/workqueue.h>
25#include <linux/slab.h>
26#include <net/tcp.h>
27#include <net/udp.h>
28#include <asm/unaligned.h>
29#include <trace/events/napi.h>
30
31/*
32 * We maintain a small pool of fully-sized skbs, to make sure the
33 * message gets out even in extreme OOM situations.
34 */
35
36#define MAX_UDP_CHUNK 1460
37#define MAX_SKBS 32
38
39static struct sk_buff_head skb_pool;
40
41static atomic_t trapped;
42
43#define USEC_PER_POLL	50
44#define NETPOLL_RX_ENABLED  1
45#define NETPOLL_RX_DROP     2
46
47#define MAX_SKB_SIZE \
48		(MAX_UDP_CHUNK + sizeof(struct udphdr) + \
49				sizeof(struct iphdr) + sizeof(struct ethhdr))
50
51static void zap_completion_queue(void);
52static void arp_reply(struct sk_buff *skb);
53
54static unsigned int carrier_timeout = 4;
55module_param(carrier_timeout, uint, 0644);
56
57static void queue_process(struct work_struct *work)
58{
59	struct netpoll_info *npinfo =
60		container_of(work, struct netpoll_info, tx_work.work);
61	struct sk_buff *skb;
62	unsigned long flags;
63
64	while ((skb = skb_dequeue(&npinfo->txq))) {
65		struct net_device *dev = skb->dev;
66		const struct net_device_ops *ops = dev->netdev_ops;
67		struct netdev_queue *txq;
68
69		if (!netif_device_present(dev) || !netif_running(dev)) {
70			__kfree_skb(skb);
71			continue;
72		}
73
74		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
75
76		local_irq_save(flags);
77		__netif_tx_lock(txq, smp_processor_id());
78		if (netif_tx_queue_frozen_or_stopped(txq) ||
79		    ops->ndo_start_xmit(skb, dev) != NETDEV_TX_OK) {
80			skb_queue_head(&npinfo->txq, skb);
81			__netif_tx_unlock(txq);
82			local_irq_restore(flags);
83
84			schedule_delayed_work(&npinfo->tx_work, HZ/10);
85			return;
86		}
87		__netif_tx_unlock(txq);
88		local_irq_restore(flags);
89	}
90}
91
92static __sum16 checksum_udp(struct sk_buff *skb, struct udphdr *uh,
93			    unsigned short ulen, __be32 saddr, __be32 daddr)
94{
95	__wsum psum;
96
97	if (uh->check == 0 || skb_csum_unnecessary(skb))
98		return 0;
99
100	psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
101
102	if (skb->ip_summed == CHECKSUM_COMPLETE &&
103	    !csum_fold(csum_add(psum, skb->csum)))
104		return 0;
105
106	skb->csum = psum;
107
108	return __skb_checksum_complete(skb);
109}
110
111/*
112 * Check whether delayed processing was scheduled for our NIC. If so,
113 * we attempt to grab the poll lock and use ->poll() to pump the card.
114 * If this fails, either we've recursed in ->poll() or it's already
115 * running on another CPU.
116 *
117 * Note: we don't mask interrupts with this lock because we're using
118 * trylock here and interrupts are already disabled in the softirq
119 * case. Further, we test the poll_owner to avoid recursion on UP
120 * systems where the lock doesn't exist.
121 *
122 * In cases where there is bi-directional communications, reading only
123 * one message at a time can lead to packets being dropped by the
124 * network adapter, forcing superfluous retries and possibly timeouts.
125 * Thus, we set our budget to greater than 1.
126 */
127static int poll_one_napi(struct netpoll_info *npinfo,
128			 struct napi_struct *napi, int budget)
129{
130	int work;
131
132	/* net_rx_action's ->poll() invocations and our's are
133	 * synchronized by this test which is only made while
134	 * holding the napi->poll_lock.
135	 */
136	if (!test_bit(NAPI_STATE_SCHED, &napi->state))
137		return budget;
138
139	npinfo->rx_flags |= NETPOLL_RX_DROP;
140	atomic_inc(&trapped);
141	set_bit(NAPI_STATE_NPSVC, &napi->state);
142
143	work = napi->poll(napi, budget);
144	trace_napi_poll(napi);
145
146	clear_bit(NAPI_STATE_NPSVC, &napi->state);
147	atomic_dec(&trapped);
148	npinfo->rx_flags &= ~NETPOLL_RX_DROP;
149
150	return budget - work;
151}
152
153static void poll_napi(struct net_device *dev)
154{
155	struct napi_struct *napi;
156	int budget = 16;
157
158	list_for_each_entry(napi, &dev->napi_list, dev_list) {
159		if (napi->poll_owner != smp_processor_id() &&
160		    spin_trylock(&napi->poll_lock)) {
161			budget = poll_one_napi(dev->npinfo, napi, budget);
162			spin_unlock(&napi->poll_lock);
163
164			if (!budget)
165				break;
166		}
167	}
168}
169
170static void service_arp_queue(struct netpoll_info *npi)
171{
172	if (npi) {
173		struct sk_buff *skb;
174
175		while ((skb = skb_dequeue(&npi->arp_tx)))
176			arp_reply(skb);
177	}
178}
179
180static void netpoll_poll_dev(struct net_device *dev)
181{
182	const struct net_device_ops *ops;
183
184	if (!dev || !netif_running(dev))
185		return;
186
187	ops = dev->netdev_ops;
188	if (!ops->ndo_poll_controller)
189		return;
190
191	/* Process pending work on NIC */
192	ops->ndo_poll_controller(dev);
193
194	poll_napi(dev);
195
196	if (dev->priv_flags & IFF_SLAVE) {
197		if (dev->npinfo) {
198			struct net_device *bond_dev = dev->master;
199			struct sk_buff *skb;
200			while ((skb = skb_dequeue(&dev->npinfo->arp_tx))) {
201				skb->dev = bond_dev;
202				skb_queue_tail(&bond_dev->npinfo->arp_tx, skb);
203			}
204		}
205	}
206
207	service_arp_queue(dev->npinfo);
208
209	zap_completion_queue();
210}
211
212static void refill_skbs(void)
213{
214	struct sk_buff *skb;
215	unsigned long flags;
216
217	spin_lock_irqsave(&skb_pool.lock, flags);
218	while (skb_pool.qlen < MAX_SKBS) {
219		skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
220		if (!skb)
221			break;
222
223		__skb_queue_tail(&skb_pool, skb);
224	}
225	spin_unlock_irqrestore(&skb_pool.lock, flags);
226}
227
228static void zap_completion_queue(void)
229{
230	unsigned long flags;
231	struct softnet_data *sd = &get_cpu_var(softnet_data);
232
233	if (sd->completion_queue) {
234		struct sk_buff *clist;
235
236		local_irq_save(flags);
237		clist = sd->completion_queue;
238		sd->completion_queue = NULL;
239		local_irq_restore(flags);
240
241		while (clist != NULL) {
242			struct sk_buff *skb = clist;
243			clist = clist->next;
244			if (skb->destructor) {
245				atomic_inc(&skb->users);
246				dev_kfree_skb_any(skb); /* put this one back */
247			} else {
248				__kfree_skb(skb);
249			}
250		}
251	}
252
253	put_cpu_var(softnet_data);
254}
255
256static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
257{
258	int count = 0;
259	struct sk_buff *skb;
260
261	zap_completion_queue();
262	refill_skbs();
263repeat:
264
265	skb = alloc_skb(len, GFP_ATOMIC);
266	if (!skb)
267		skb = skb_dequeue(&skb_pool);
268
269	if (!skb) {
270		if (++count < 10) {
271			netpoll_poll_dev(np->dev);
272			goto repeat;
273		}
274		return NULL;
275	}
276
277	atomic_set(&skb->users, 1);
278	skb_reserve(skb, reserve);
279	return skb;
280}
281
282static int netpoll_owner_active(struct net_device *dev)
283{
284	struct napi_struct *napi;
285
286	list_for_each_entry(napi, &dev->napi_list, dev_list) {
287		if (napi->poll_owner == smp_processor_id())
288			return 1;
289	}
290	return 0;
291}
292
293void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
294			     struct net_device *dev)
295{
296	int status = NETDEV_TX_BUSY;
297	unsigned long tries;
298	const struct net_device_ops *ops = dev->netdev_ops;
299	/* It is up to the caller to keep npinfo alive. */
300	struct netpoll_info *npinfo = np->dev->npinfo;
301
302	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
303		__kfree_skb(skb);
304		return;
305	}
306
307	/* don't get messages out of order, and no recursion */
308	if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
309		struct netdev_queue *txq;
310		unsigned long flags;
311
312		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
313
314		local_irq_save(flags);
315		/* try until next clock tick */
316		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
317		     tries > 0; --tries) {
318			if (__netif_tx_trylock(txq)) {
319				if (!netif_tx_queue_stopped(txq)) {
320					status = ops->ndo_start_xmit(skb, dev);
321					if (status == NETDEV_TX_OK)
322						txq_trans_update(txq);
323				}
324				__netif_tx_unlock(txq);
325
326				if (status == NETDEV_TX_OK)
327					break;
328
329			}
330
331			/* tickle device maybe there is some cleanup */
332			netpoll_poll_dev(np->dev);
333
334			udelay(USEC_PER_POLL);
335		}
336
337		WARN_ONCE(!irqs_disabled(),
338			"netpoll_send_skb(): %s enabled interrupts in poll (%pF)\n",
339			dev->name, ops->ndo_start_xmit);
340
341		local_irq_restore(flags);
342	}
343
344	if (status != NETDEV_TX_OK) {
345		skb_queue_tail(&npinfo->txq, skb);
346		schedule_delayed_work(&npinfo->tx_work,0);
347	}
348}
349EXPORT_SYMBOL(netpoll_send_skb_on_dev);
350
351void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
352{
353	int total_len, eth_len, ip_len, udp_len;
354	struct sk_buff *skb;
355	struct udphdr *udph;
356	struct iphdr *iph;
357	struct ethhdr *eth;
358
359	udp_len = len + sizeof(*udph);
360	ip_len = eth_len = udp_len + sizeof(*iph);
361	total_len = eth_len + ETH_HLEN + NET_IP_ALIGN;
362
363	skb = find_skb(np, total_len, total_len - len);
364	if (!skb)
365		return;
366
367	skb_copy_to_linear_data(skb, msg, len);
368	skb->len += len;
369
370	skb_push(skb, sizeof(*udph));
371	skb_reset_transport_header(skb);
372	udph = udp_hdr(skb);
373	udph->source = htons(np->local_port);
374	udph->dest = htons(np->remote_port);
375	udph->len = htons(udp_len);
376	udph->check = 0;
377	udph->check = csum_tcpudp_magic(np->local_ip,
378					np->remote_ip,
379					udp_len, IPPROTO_UDP,
380					csum_partial(udph, udp_len, 0));
381	if (udph->check == 0)
382		udph->check = CSUM_MANGLED_0;
383
384	skb_push(skb, sizeof(*iph));
385	skb_reset_network_header(skb);
386	iph = ip_hdr(skb);
387
388	/* iph->version = 4; iph->ihl = 5; */
389	put_unaligned(0x45, (unsigned char *)iph);
390	iph->tos      = 0;
391	put_unaligned(htons(ip_len), &(iph->tot_len));
392	iph->id       = 0;
393	iph->frag_off = 0;
394	iph->ttl      = 64;
395	iph->protocol = IPPROTO_UDP;
396	iph->check    = 0;
397	put_unaligned(np->local_ip, &(iph->saddr));
398	put_unaligned(np->remote_ip, &(iph->daddr));
399	iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
400
401	eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
402	skb_reset_mac_header(skb);
403	skb->protocol = eth->h_proto = htons(ETH_P_IP);
404	memcpy(eth->h_source, np->dev->dev_addr, ETH_ALEN);
405	memcpy(eth->h_dest, np->remote_mac, ETH_ALEN);
406
407	skb->dev = np->dev;
408
409	netpoll_send_skb(np, skb);
410}
411EXPORT_SYMBOL(netpoll_send_udp);
412
413static void arp_reply(struct sk_buff *skb)
414{
415	struct netpoll_info *npinfo = skb->dev->npinfo;
416	struct arphdr *arp;
417	unsigned char *arp_ptr;
418	int size, type = ARPOP_REPLY, ptype = ETH_P_ARP;
419	__be32 sip, tip;
420	unsigned char *sha;
421	struct sk_buff *send_skb;
422	struct netpoll *np, *tmp;
423	unsigned long flags;
424	int hits = 0;
425
426	if (list_empty(&npinfo->rx_np))
427		return;
428
429	/* Before checking the packet, we do some early
430	   inspection whether this is interesting at all */
431	spin_lock_irqsave(&npinfo->rx_lock, flags);
432	list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
433		if (np->dev == skb->dev)
434			hits++;
435	}
436	spin_unlock_irqrestore(&npinfo->rx_lock, flags);
437
438	/* No netpoll struct is using this dev */
439	if (!hits)
440		return;
441
442	/* No arp on this interface */
443	if (skb->dev->flags & IFF_NOARP)
444		return;
445
446	if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
447		return;
448
449	skb_reset_network_header(skb);
450	skb_reset_transport_header(skb);
451	arp = arp_hdr(skb);
452
453	if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
454	     arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
455	    arp->ar_pro != htons(ETH_P_IP) ||
456	    arp->ar_op != htons(ARPOP_REQUEST))
457		return;
458
459	arp_ptr = (unsigned char *)(arp+1);
460	/* save the location of the src hw addr */
461	sha = arp_ptr;
462	arp_ptr += skb->dev->addr_len;
463	memcpy(&sip, arp_ptr, 4);
464	arp_ptr += 4;
465	/* If we actually cared about dst hw addr,
466	   it would get copied here */
467	arp_ptr += skb->dev->addr_len;
468	memcpy(&tip, arp_ptr, 4);
469
470	/* Should we ignore arp? */
471	if (ipv4_is_loopback(tip) || ipv4_is_multicast(tip))
472		return;
473
474	size = arp_hdr_len(skb->dev);
475
476	spin_lock_irqsave(&npinfo->rx_lock, flags);
477	list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
478		if (tip != np->local_ip)
479			continue;
480
481		send_skb = find_skb(np, size + LL_ALLOCATED_SPACE(np->dev),
482				    LL_RESERVED_SPACE(np->dev));
483		if (!send_skb)
484			continue;
485
486		skb_reset_network_header(send_skb);
487		arp = (struct arphdr *) skb_put(send_skb, size);
488		send_skb->dev = skb->dev;
489		send_skb->protocol = htons(ETH_P_ARP);
490
491		/* Fill the device header for the ARP frame */
492		if (dev_hard_header(send_skb, skb->dev, ptype,
493				    sha, np->dev->dev_addr,
494				    send_skb->len) < 0) {
495			kfree_skb(send_skb);
496			continue;
497		}
498
499		/*
500		 * Fill out the arp protocol part.
501		 *
502		 * we only support ethernet device type,
503		 * which (according to RFC 1390) should
504		 * always equal 1 (Ethernet).
505		 */
506
507		arp->ar_hrd = htons(np->dev->type);
508		arp->ar_pro = htons(ETH_P_IP);
509		arp->ar_hln = np->dev->addr_len;
510		arp->ar_pln = 4;
511		arp->ar_op = htons(type);
512
513		arp_ptr = (unsigned char *)(arp + 1);
514		memcpy(arp_ptr, np->dev->dev_addr, np->dev->addr_len);
515		arp_ptr += np->dev->addr_len;
516		memcpy(arp_ptr, &tip, 4);
517		arp_ptr += 4;
518		memcpy(arp_ptr, sha, np->dev->addr_len);
519		arp_ptr += np->dev->addr_len;
520		memcpy(arp_ptr, &sip, 4);
521
522		netpoll_send_skb(np, send_skb);
523
524		/* If there are several rx_hooks for the same address,
525		   we're fine by sending a single reply */
526		break;
527	}
528	spin_unlock_irqrestore(&npinfo->rx_lock, flags);
529}
530
531int __netpoll_rx(struct sk_buff *skb)
532{
533	int proto, len, ulen;
534	int hits = 0;
535	const struct iphdr *iph;
536	struct udphdr *uh;
537	struct netpoll_info *npinfo = skb->dev->npinfo;
538	struct netpoll *np, *tmp;
539
540	if (list_empty(&npinfo->rx_np))
541		goto out;
542
543	if (skb->dev->type != ARPHRD_ETHER)
544		goto out;
545
546	/* check if netpoll clients need ARP */
547	if (skb->protocol == htons(ETH_P_ARP) &&
548	    atomic_read(&trapped)) {
549		skb_queue_tail(&npinfo->arp_tx, skb);
550		return 1;
551	}
552
553	proto = ntohs(eth_hdr(skb)->h_proto);
554	if (proto != ETH_P_IP)
555		goto out;
556	if (skb->pkt_type == PACKET_OTHERHOST)
557		goto out;
558	if (skb_shared(skb))
559		goto out;
560
561	iph = (struct iphdr *)skb->data;
562	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
563		goto out;
564	if (iph->ihl < 5 || iph->version != 4)
565		goto out;
566	if (!pskb_may_pull(skb, iph->ihl*4))
567		goto out;
568	if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
569		goto out;
570
571	len = ntohs(iph->tot_len);
572	if (skb->len < len || len < iph->ihl*4)
573		goto out;
574
575	/*
576	 * Our transport medium may have padded the buffer out.
577	 * Now We trim to the true length of the frame.
578	 */
579	if (pskb_trim_rcsum(skb, len))
580		goto out;
581
582	if (iph->protocol != IPPROTO_UDP)
583		goto out;
584
585	len -= iph->ihl*4;
586	uh = (struct udphdr *)(((char *)iph) + iph->ihl*4);
587	ulen = ntohs(uh->len);
588
589	if (ulen != len)
590		goto out;
591	if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
592		goto out;
593
594	list_for_each_entry_safe(np, tmp, &npinfo->rx_np, rx) {
595		if (np->local_ip && np->local_ip != iph->daddr)
596			continue;
597		if (np->remote_ip && np->remote_ip != iph->saddr)
598			continue;
599		if (np->local_port && np->local_port != ntohs(uh->dest))
600			continue;
601
602		np->rx_hook(np, ntohs(uh->source),
603			       (char *)(uh+1),
604			       ulen - sizeof(struct udphdr));
605		hits++;
606	}
607
608	if (!hits)
609		goto out;
610
611	kfree_skb(skb);
612	return 1;
613
614out:
615	if (atomic_read(&trapped)) {
616		kfree_skb(skb);
617		return 1;
618	}
619
620	return 0;
621}
622
623void netpoll_print_options(struct netpoll *np)
624{
625	printk(KERN_INFO "%s: local port %d\n",
626			 np->name, np->local_port);
627	printk(KERN_INFO "%s: local IP %pI4\n",
628			 np->name, &np->local_ip);
629	printk(KERN_INFO "%s: interface '%s'\n",
630			 np->name, np->dev_name);
631	printk(KERN_INFO "%s: remote port %d\n",
632			 np->name, np->remote_port);
633	printk(KERN_INFO "%s: remote IP %pI4\n",
634			 np->name, &np->remote_ip);
635	printk(KERN_INFO "%s: remote ethernet address %pM\n",
636	                 np->name, np->remote_mac);
637}
638EXPORT_SYMBOL(netpoll_print_options);
639
640int netpoll_parse_options(struct netpoll *np, char *opt)
641{
642	char *cur=opt, *delim;
643
644	if (*cur != '@') {
645		if ((delim = strchr(cur, '@')) == NULL)
646			goto parse_failed;
647		*delim = 0;
648		np->local_port = simple_strtol(cur, NULL, 10);
649		cur = delim;
650	}
651	cur++;
652
653	if (*cur != '/') {
654		if ((delim = strchr(cur, '/')) == NULL)
655			goto parse_failed;
656		*delim = 0;
657		np->local_ip = in_aton(cur);
658		cur = delim;
659	}
660	cur++;
661
662	if (*cur != ',') {
663		/* parse out dev name */
664		if ((delim = strchr(cur, ',')) == NULL)
665			goto parse_failed;
666		*delim = 0;
667		strlcpy(np->dev_name, cur, sizeof(np->dev_name));
668		cur = delim;
669	}
670	cur++;
671
672	if (*cur != '@') {
673		/* dst port */
674		if ((delim = strchr(cur, '@')) == NULL)
675			goto parse_failed;
676		*delim = 0;
677		if (*cur == ' ' || *cur == '\t')
678			printk(KERN_INFO "%s: warning: whitespace"
679					"is not allowed\n", np->name);
680		np->remote_port = simple_strtol(cur, NULL, 10);
681		cur = delim;
682	}
683	cur++;
684
685	/* dst ip */
686	if ((delim = strchr(cur, '/')) == NULL)
687		goto parse_failed;
688	*delim = 0;
689	np->remote_ip = in_aton(cur);
690	cur = delim + 1;
691
692	if (*cur != 0) {
693		/* MAC address */
694		if (!mac_pton(cur, np->remote_mac))
695			goto parse_failed;
696	}
697
698	netpoll_print_options(np);
699
700	return 0;
701
702 parse_failed:
703	printk(KERN_INFO "%s: couldn't parse config at '%s'!\n",
704	       np->name, cur);
705	return -1;
706}
707EXPORT_SYMBOL(netpoll_parse_options);
708
709int __netpoll_setup(struct netpoll *np)
710{
711	struct net_device *ndev = np->dev;
712	struct netpoll_info *npinfo;
713	const struct net_device_ops *ops;
714	unsigned long flags;
715	int err;
716
717	if ((ndev->priv_flags & IFF_DISABLE_NETPOLL) ||
718	    !ndev->netdev_ops->ndo_poll_controller) {
719		printk(KERN_ERR "%s: %s doesn't support polling, aborting.\n",
720		       np->name, np->dev_name);
721		err = -ENOTSUPP;
722		goto out;
723	}
724
725	if (!ndev->npinfo) {
726		npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
727		if (!npinfo) {
728			err = -ENOMEM;
729			goto out;
730		}
731
732		npinfo->rx_flags = 0;
733		INIT_LIST_HEAD(&npinfo->rx_np);
734
735		spin_lock_init(&npinfo->rx_lock);
736		skb_queue_head_init(&npinfo->arp_tx);
737		skb_queue_head_init(&npinfo->txq);
738		INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
739
740		atomic_set(&npinfo->refcnt, 1);
741
742		ops = np->dev->netdev_ops;
743		if (ops->ndo_netpoll_setup) {
744			err = ops->ndo_netpoll_setup(ndev, npinfo);
745			if (err)
746				goto free_npinfo;
747		}
748	} else {
749		npinfo = ndev->npinfo;
750		atomic_inc(&npinfo->refcnt);
751	}
752
753	npinfo->netpoll = np;
754
755	if (np->rx_hook) {
756		spin_lock_irqsave(&npinfo->rx_lock, flags);
757		npinfo->rx_flags |= NETPOLL_RX_ENABLED;
758		list_add_tail(&np->rx, &npinfo->rx_np);
759		spin_unlock_irqrestore(&npinfo->rx_lock, flags);
760	}
761
762	/* last thing to do is link it to the net device structure */
763	RCU_INIT_POINTER(ndev->npinfo, npinfo);
764
765	return 0;
766
767free_npinfo:
768	kfree(npinfo);
769out:
770	return err;
771}
772EXPORT_SYMBOL_GPL(__netpoll_setup);
773
774int netpoll_setup(struct netpoll *np)
775{
776	struct net_device *ndev = NULL;
777	struct in_device *in_dev;
778	int err;
779
780	if (np->dev_name)
781		ndev = dev_get_by_name(&init_net, np->dev_name);
782	if (!ndev) {
783		printk(KERN_ERR "%s: %s doesn't exist, aborting.\n",
784		       np->name, np->dev_name);
785		return -ENODEV;
786	}
787
788	if (ndev->master) {
789		printk(KERN_ERR "%s: %s is a slave device, aborting.\n",
790		       np->name, np->dev_name);
791		err = -EBUSY;
792		goto put;
793	}
794
795	if (!netif_running(ndev)) {
796		unsigned long atmost, atleast;
797
798		printk(KERN_INFO "%s: device %s not up yet, forcing it\n",
799		       np->name, np->dev_name);
800
801		rtnl_lock();
802		err = dev_open(ndev);
803		rtnl_unlock();
804
805		if (err) {
806			printk(KERN_ERR "%s: failed to open %s\n",
807			       np->name, ndev->name);
808			goto put;
809		}
810
811		atleast = jiffies + HZ/10;
812		atmost = jiffies + carrier_timeout * HZ;
813		while (!netif_carrier_ok(ndev)) {
814			if (time_after(jiffies, atmost)) {
815				printk(KERN_NOTICE
816				       "%s: timeout waiting for carrier\n",
817				       np->name);
818				break;
819			}
820			msleep(1);
821		}
822
823		/* If carrier appears to come up instantly, we don't
824		 * trust it and pause so that we don't pump all our
825		 * queued console messages into the bitbucket.
826		 */
827
828		if (time_before(jiffies, atleast)) {
829			printk(KERN_NOTICE "%s: carrier detect appears"
830			       " untrustworthy, waiting 4 seconds\n",
831			       np->name);
832			msleep(4000);
833		}
834	}
835
836	if (!np->local_ip) {
837		rcu_read_lock();
838		in_dev = __in_dev_get_rcu(ndev);
839
840		if (!in_dev || !in_dev->ifa_list) {
841			rcu_read_unlock();
842			printk(KERN_ERR "%s: no IP address for %s, aborting\n",
843			       np->name, np->dev_name);
844			err = -EDESTADDRREQ;
845			goto put;
846		}
847
848		np->local_ip = in_dev->ifa_list->ifa_local;
849		rcu_read_unlock();
850		printk(KERN_INFO "%s: local IP %pI4\n", np->name, &np->local_ip);
851	}
852
853	np->dev = ndev;
854
855	/* fill up the skb queue */
856	refill_skbs();
857
858	rtnl_lock();
859	err = __netpoll_setup(np);
860	rtnl_unlock();
861
862	if (err)
863		goto put;
864
865	return 0;
866
867put:
868	dev_put(ndev);
869	return err;
870}
871EXPORT_SYMBOL(netpoll_setup);
872
873static int __init netpoll_init(void)
874{
875	skb_queue_head_init(&skb_pool);
876	return 0;
877}
878core_initcall(netpoll_init);
879
880void __netpoll_cleanup(struct netpoll *np)
881{
882	struct netpoll_info *npinfo;
883	unsigned long flags;
884
885	npinfo = np->dev->npinfo;
886	if (!npinfo)
887		return;
888
889	if (!list_empty(&npinfo->rx_np)) {
890		spin_lock_irqsave(&npinfo->rx_lock, flags);
891		list_del(&np->rx);
892		if (list_empty(&npinfo->rx_np))
893			npinfo->rx_flags &= ~NETPOLL_RX_ENABLED;
894		spin_unlock_irqrestore(&npinfo->rx_lock, flags);
895	}
896
897	if (atomic_dec_and_test(&npinfo->refcnt)) {
898		const struct net_device_ops *ops;
899
900		ops = np->dev->netdev_ops;
901		if (ops->ndo_netpoll_cleanup)
902			ops->ndo_netpoll_cleanup(np->dev);
903
904		RCU_INIT_POINTER(np->dev->npinfo, NULL);
905
906		/* avoid racing with NAPI reading npinfo */
907		synchronize_rcu_bh();
908
909		skb_queue_purge(&npinfo->arp_tx);
910		skb_queue_purge(&npinfo->txq);
911		cancel_delayed_work_sync(&npinfo->tx_work);
912
913		/* clean after last, unfinished work */
914		__skb_queue_purge(&npinfo->txq);
915		kfree(npinfo);
916	}
917}
918EXPORT_SYMBOL_GPL(__netpoll_cleanup);
919
920void netpoll_cleanup(struct netpoll *np)
921{
922	if (!np->dev)
923		return;
924
925	rtnl_lock();
926	__netpoll_cleanup(np);
927	rtnl_unlock();
928
929	dev_put(np->dev);
930	np->dev = NULL;
931}
932EXPORT_SYMBOL(netpoll_cleanup);
933
934int netpoll_trap(void)
935{
936	return atomic_read(&trapped);
937}
938EXPORT_SYMBOL(netpoll_trap);
939
940void netpoll_set_trap(int trap)
941{
942	if (trap)
943		atomic_inc(&trapped);
944	else
945		atomic_dec(&trapped);
946}
947EXPORT_SYMBOL(netpoll_set_trap);
948