netpoll.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Common framework for low-level network console, dump, and debugger code
  4 *
  5 * Sep 8 2003  Matt Mackall <mpm@selenic.com>
  6 *
  7 * based on the netconsole code from:
  8 *
  9 * Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
 10 * Copyright (C) 2002  Red Hat, Inc.
 11 */
 12
 13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 14
 15#include <linux/moduleparam.h>
 16#include <linux/kernel.h>
 17#include <linux/netdevice.h>
 18#include <linux/etherdevice.h>
 19#include <linux/string.h>
 20#include <linux/if_arp.h>
 21#include <linux/inetdevice.h>
 22#include <linux/inet.h>
 23#include <linux/interrupt.h>
 24#include <linux/netpoll.h>
 25#include <linux/sched.h>
 26#include <linux/delay.h>
 27#include <linux/rcupdate.h>
 28#include <linux/workqueue.h>
 29#include <linux/slab.h>
 30#include <linux/export.h>
 31#include <linux/if_vlan.h>
 32#include <net/tcp.h>
 33#include <net/udp.h>
 34#include <net/addrconf.h>
 35#include <net/ndisc.h>
 36#include <net/ip6_checksum.h>
 37#include <linux/unaligned.h>
 38#include <trace/events/napi.h>
 39#include <linux/kconfig.h>
 40
 41/*
 42 * We maintain a small pool of fully-sized skbs, to make sure the
 43 * message gets out even in extreme OOM situations.
 44 */
 45
 46#define MAX_UDP_CHUNK 1460
 47#define MAX_SKBS 32
 48#define USEC_PER_POLL	50
 49
 50#define MAX_SKB_SIZE							\
 51	(sizeof(struct ethhdr) +					\
 52	 sizeof(struct iphdr) +						\
 53	 sizeof(struct udphdr) +					\
 54	 MAX_UDP_CHUNK)
 55
 56static void zap_completion_queue(void);
 57
 58static unsigned int carrier_timeout = 4;
 59module_param(carrier_timeout, uint, 0644);
 60
 61static netdev_tx_t netpoll_start_xmit(struct sk_buff *skb,
 62				      struct net_device *dev,
 63				      struct netdev_queue *txq)
 64{
 65	netdev_tx_t status = NETDEV_TX_OK;
 66	netdev_features_t features;
 67
 68	features = netif_skb_features(skb);
 69
 70	if (skb_vlan_tag_present(skb) &&
 71	    !vlan_hw_offload_capable(features, skb->vlan_proto)) {
 72		skb = __vlan_hwaccel_push_inside(skb);
 73		if (unlikely(!skb)) {
 74			/* This is actually a packet drop, but we
 75			 * don't want the code that calls this
 76			 * function to try and operate on a NULL skb.
 77			 */
 78			goto out;
 79		}
 80	}
 81
 82	status = netdev_start_xmit(skb, dev, txq, false);
 83
 84out:
 85	return status;
 86}
 87
 88static void queue_process(struct work_struct *work)
 89{
 90	struct netpoll_info *npinfo =
 91		container_of(work, struct netpoll_info, tx_work.work);
 92	struct sk_buff *skb;
 93	unsigned long flags;
 94
 95	while ((skb = skb_dequeue(&npinfo->txq))) {
 96		struct net_device *dev = skb->dev;
 97		struct netdev_queue *txq;
 98		unsigned int q_index;
 99
100		if (!netif_device_present(dev) || !netif_running(dev)) {
101			kfree_skb(skb);
102			continue;
103		}
104
105		local_irq_save(flags);
106		/* check if skb->queue_mapping is still valid */
107		q_index = skb_get_queue_mapping(skb);
108		if (unlikely(q_index >= dev->real_num_tx_queues)) {
109			q_index = q_index % dev->real_num_tx_queues;
110			skb_set_queue_mapping(skb, q_index);
111		}
112		txq = netdev_get_tx_queue(dev, q_index);
113		HARD_TX_LOCK(dev, txq, smp_processor_id());
114		if (netif_xmit_frozen_or_stopped(txq) ||
115		    !dev_xmit_complete(netpoll_start_xmit(skb, dev, txq))) {
116			skb_queue_head(&npinfo->txq, skb);
117			HARD_TX_UNLOCK(dev, txq);
118			local_irq_restore(flags);
119
120			schedule_delayed_work(&npinfo->tx_work, HZ/10);
121			return;
122		}
123		HARD_TX_UNLOCK(dev, txq);
124		local_irq_restore(flags);
125	}
126}
127
128static int netif_local_xmit_active(struct net_device *dev)
129{
130	int i;
131
132	for (i = 0; i < dev->num_tx_queues; i++) {
133		struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
134
135		if (netif_tx_owned(txq, smp_processor_id()))
136			return 1;
137	}
138
139	return 0;
140}
141
142static void poll_one_napi(struct napi_struct *napi)
143{
144	int work;
145
146	/* If we set this bit but see that it has already been set,
147	 * that indicates that napi has been disabled and we need
148	 * to abort this operation
149	 */
150	if (test_and_set_bit(NAPI_STATE_NPSVC, &napi->state))
151		return;
152
153	/* We explicitly pass the polling call a budget of 0 to
154	 * indicate that we are clearing the Tx path only.
155	 */
156	work = napi->poll(napi, 0);
157	WARN_ONCE(work, "%pS exceeded budget in poll\n", napi->poll);
158	trace_napi_poll(napi, work, 0);
159
160	clear_bit(NAPI_STATE_NPSVC, &napi->state);
161}
162
163static void poll_napi(struct net_device *dev)
164{
165	struct napi_struct *napi;
166	int cpu = smp_processor_id();
167
168	list_for_each_entry_rcu(napi, &dev->napi_list, dev_list) {
169		if (cmpxchg(&napi->poll_owner, -1, cpu) == -1) {
170			poll_one_napi(napi);
171			smp_store_release(&napi->poll_owner, -1);
172		}
173	}
174}
175
176void netpoll_poll_dev(struct net_device *dev)
177{
178	struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo);
179	const struct net_device_ops *ops;
180
181	/* Don't do any rx activity if the dev_lock mutex is held
182	 * the dev_open/close paths use this to block netpoll activity
183	 * while changing device state
184	 */
185	if (!ni || down_trylock(&ni->dev_lock))
186		return;
187
188	/* Some drivers will take the same locks in poll and xmit,
189	 * we can't poll if local CPU is already in xmit.
190	 */
191	if (!netif_running(dev) || netif_local_xmit_active(dev)) {
192		up(&ni->dev_lock);
193		return;
194	}
195
196	ops = dev->netdev_ops;
197	if (ops->ndo_poll_controller)
198		ops->ndo_poll_controller(dev);
199
200	poll_napi(dev);
201
202	up(&ni->dev_lock);
203
204	zap_completion_queue();
205}
206EXPORT_SYMBOL(netpoll_poll_dev);
207
208void netpoll_poll_disable(struct net_device *dev)
209{
210	struct netpoll_info *ni;
211
212	might_sleep();
213	ni = rtnl_dereference(dev->npinfo);
214	if (ni)
215		down(&ni->dev_lock);
216}
217
218void netpoll_poll_enable(struct net_device *dev)
219{
220	struct netpoll_info *ni;
221
222	ni = rtnl_dereference(dev->npinfo);
223	if (ni)
224		up(&ni->dev_lock);
225}
226
227static void refill_skbs(struct netpoll *np)
228{
229	struct sk_buff_head *skb_pool;
230	struct sk_buff *skb;
231
232	skb_pool = &np->skb_pool;
233
234	while (READ_ONCE(skb_pool->qlen) < MAX_SKBS) {
235		skb = alloc_skb(MAX_SKB_SIZE, GFP_ATOMIC);
236		if (!skb)
237			break;
238
239		skb_queue_tail(skb_pool, skb);
240	}
241}
242
243static void zap_completion_queue(void)
244{
245	unsigned long flags;
246	struct softnet_data *sd = &get_cpu_var(softnet_data);
247
248	if (sd->completion_queue) {
249		struct sk_buff *clist;
250
251		local_irq_save(flags);
252		clist = sd->completion_queue;
253		sd->completion_queue = NULL;
254		local_irq_restore(flags);
255
256		while (clist != NULL) {
257			struct sk_buff *skb = clist;
258			clist = clist->next;
259			if (!skb_irq_freeable(skb)) {
260				refcount_set(&skb->users, 1);
261				dev_kfree_skb_any(skb); /* put this one back */
262			} else {
263				__kfree_skb(skb);
264			}
265		}
266	}
267
268	put_cpu_var(softnet_data);
269}
270
271static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
272{
273	int count = 0;
274	struct sk_buff *skb;
275
276	zap_completion_queue();
277repeat:
278
279	skb = alloc_skb(len, GFP_ATOMIC);
280	if (!skb) {
281		skb = skb_dequeue(&np->skb_pool);
282		schedule_work(&np->refill_wq);
283	}
284
285	if (!skb) {
286		if (++count < 10) {
287			netpoll_poll_dev(np->dev);
288			goto repeat;
289		}
290		return NULL;
291	}
292
293	refcount_set(&skb->users, 1);
294	skb_reserve(skb, reserve);
295	return skb;
296}
297
298static int netpoll_owner_active(struct net_device *dev)
299{
300	struct napi_struct *napi;
301
302	list_for_each_entry_rcu(napi, &dev->napi_list, dev_list) {
303		if (READ_ONCE(napi->poll_owner) == smp_processor_id())
304			return 1;
305	}
306	return 0;
307}
308
309/* call with IRQ disabled */
310static netdev_tx_t __netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
311{
312	netdev_tx_t status = NETDEV_TX_BUSY;
313	netdev_tx_t ret = NET_XMIT_DROP;
314	struct net_device *dev;
315	unsigned long tries;
316	/* It is up to the caller to keep npinfo alive. */
317	struct netpoll_info *npinfo;
318
319	lockdep_assert_irqs_disabled();
320
321	dev = np->dev;
322	rcu_read_lock();
323	npinfo = rcu_dereference_bh(dev->npinfo);
324
325	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
326		dev_kfree_skb_irq(skb);
327		goto out;
328	}
329
330	/* don't get messages out of order, and no recursion */
331	if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
332		struct netdev_queue *txq;
333
334		txq = netdev_core_pick_tx(dev, skb, NULL);
335
336		/* try until next clock tick */
337		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
338		     tries > 0; --tries) {
339			if (HARD_TX_TRYLOCK(dev, txq)) {
340				if (!netif_xmit_stopped(txq))
341					status = netpoll_start_xmit(skb, dev, txq);
342
343				HARD_TX_UNLOCK(dev, txq);
344
345				if (dev_xmit_complete(status))
346					break;
347
348			}
349
350			/* tickle device maybe there is some cleanup */
351			netpoll_poll_dev(np->dev);
352
353			udelay(USEC_PER_POLL);
354		}
355
356		WARN_ONCE(!irqs_disabled(),
357			"netpoll_send_skb_on_dev(): %s enabled interrupts in poll (%pS)\n",
358			dev->name, dev->netdev_ops->ndo_start_xmit);
359
360	}
361
362	if (!dev_xmit_complete(status)) {
363		skb_queue_tail(&npinfo->txq, skb);
364		schedule_delayed_work(&npinfo->tx_work,0);
365	}
366	ret = NETDEV_TX_OK;
367out:
368	rcu_read_unlock();
369	return ret;
370}
371
372static void netpoll_udp_checksum(struct netpoll *np, struct sk_buff *skb,
373				 int len)
374{
375	struct udphdr *udph;
376	int udp_len;
377
378	udp_len = len + sizeof(struct udphdr);
379	udph = udp_hdr(skb);
380
381	/* check needs to be set, since it will be consumed in csum_partial */
382	udph->check = 0;
383	if (np->ipv6)
384		udph->check = csum_ipv6_magic(&np->local_ip.in6,
385					      &np->remote_ip.in6,
386					      udp_len, IPPROTO_UDP,
387					      csum_partial(udph, udp_len, 0));
388	else
389		udph->check = csum_tcpudp_magic(np->local_ip.ip,
390						np->remote_ip.ip,
391						udp_len, IPPROTO_UDP,
392						csum_partial(udph, udp_len, 0));
393	if (udph->check == 0)
394		udph->check = CSUM_MANGLED_0;
395}
396
397netdev_tx_t netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
398{
399	unsigned long flags;
400	netdev_tx_t ret;
401
402	if (unlikely(!np)) {
403		dev_kfree_skb_irq(skb);
404		ret = NET_XMIT_DROP;
405	} else {
406		local_irq_save(flags);
407		ret = __netpoll_send_skb(np, skb);
408		local_irq_restore(flags);
409	}
410	return ret;
411}
412EXPORT_SYMBOL(netpoll_send_skb);
413
414static void push_ipv6(struct netpoll *np, struct sk_buff *skb, int len)
415{
416	struct ipv6hdr *ip6h;
417
418	skb_push(skb, sizeof(struct ipv6hdr));
419	skb_reset_network_header(skb);
420	ip6h = ipv6_hdr(skb);
421
422	/* ip6h->version = 6; ip6h->priority = 0; */
423	*(unsigned char *)ip6h = 0x60;
424	ip6h->flow_lbl[0] = 0;
425	ip6h->flow_lbl[1] = 0;
426	ip6h->flow_lbl[2] = 0;
427
428	ip6h->payload_len = htons(sizeof(struct udphdr) + len);
429	ip6h->nexthdr = IPPROTO_UDP;
430	ip6h->hop_limit = 32;
431	ip6h->saddr = np->local_ip.in6;
432	ip6h->daddr = np->remote_ip.in6;
433
434	skb->protocol = htons(ETH_P_IPV6);
435}
436
437static void push_ipv4(struct netpoll *np, struct sk_buff *skb, int len)
438{
439	static atomic_t ip_ident;
440	struct iphdr *iph;
441	int ip_len;
442
443	ip_len = len + sizeof(struct udphdr) + sizeof(struct iphdr);
444
445	skb_push(skb, sizeof(struct iphdr));
446	skb_reset_network_header(skb);
447	iph = ip_hdr(skb);
448
449	/* iph->version = 4; iph->ihl = 5; */
450	*(unsigned char *)iph = 0x45;
451	iph->tos = 0;
452	put_unaligned(htons(ip_len), &iph->tot_len);
453	iph->id = htons(atomic_inc_return(&ip_ident));
454	iph->frag_off = 0;
455	iph->ttl = 64;
456	iph->protocol = IPPROTO_UDP;
457	iph->check = 0;
458	put_unaligned(np->local_ip.ip, &iph->saddr);
459	put_unaligned(np->remote_ip.ip, &iph->daddr);
460	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
461	skb->protocol = htons(ETH_P_IP);
462}
463
464static void push_udp(struct netpoll *np, struct sk_buff *skb, int len)
465{
466	struct udphdr *udph;
467	int udp_len;
468
469	udp_len = len + sizeof(struct udphdr);
470
471	skb_push(skb, sizeof(struct udphdr));
472	skb_reset_transport_header(skb);
473
474	udph = udp_hdr(skb);
475	udph->source = htons(np->local_port);
476	udph->dest = htons(np->remote_port);
477	udph->len = htons(udp_len);
478
479	netpoll_udp_checksum(np, skb, len);
480}
481
482static void push_eth(struct netpoll *np, struct sk_buff *skb)
483{
484	struct ethhdr *eth;
485
486	eth = skb_push(skb, ETH_HLEN);
487	skb_reset_mac_header(skb);
488	ether_addr_copy(eth->h_source, np->dev->dev_addr);
489	ether_addr_copy(eth->h_dest, np->remote_mac);
490	if (np->ipv6)
491		eth->h_proto = htons(ETH_P_IPV6);
492	else
493		eth->h_proto = htons(ETH_P_IP);
494}
495
496int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
497{
498	int total_len, ip_len, udp_len;
499	struct sk_buff *skb;
500
501	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
502		WARN_ON_ONCE(!irqs_disabled());
503
504	udp_len = len + sizeof(struct udphdr);
505	if (np->ipv6)
506		ip_len = udp_len + sizeof(struct ipv6hdr);
507	else
508		ip_len = udp_len + sizeof(struct iphdr);
509
510	total_len = ip_len + LL_RESERVED_SPACE(np->dev);
511
512	skb = find_skb(np, total_len + np->dev->needed_tailroom,
513		       total_len - len);
514	if (!skb)
515		return -ENOMEM;
516
517	skb_copy_to_linear_data(skb, msg, len);
518	skb_put(skb, len);
519
520	push_udp(np, skb, len);
521	if (np->ipv6)
522		push_ipv6(np, skb, len);
523	else
524		push_ipv4(np, skb, len);
525	push_eth(np, skb);
526	skb->dev = np->dev;
527
528	return (int)netpoll_send_skb(np, skb);
529}
530EXPORT_SYMBOL(netpoll_send_udp);
531
532
533static void skb_pool_flush(struct netpoll *np)
534{
535	struct sk_buff_head *skb_pool;
536
537	cancel_work_sync(&np->refill_wq);
538	skb_pool = &np->skb_pool;
539	skb_queue_purge_reason(skb_pool, SKB_CONSUMED);
540}
541
542static void refill_skbs_work_handler(struct work_struct *work)
543{
544	struct netpoll *np =
545		container_of(work, struct netpoll, refill_wq);
546
547	refill_skbs(np);
548}
549
550int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
551{
552	struct netpoll_info *npinfo;
553	const struct net_device_ops *ops;
554	int err;
555
556	skb_queue_head_init(&np->skb_pool);
557	INIT_WORK(&np->refill_wq, refill_skbs_work_handler);
558
559	if (ndev->priv_flags & IFF_DISABLE_NETPOLL) {
560		np_err(np, "%s doesn't support polling, aborting\n",
561		       ndev->name);
562		err = -ENOTSUPP;
563		goto out;
564	}
565
566	npinfo = rtnl_dereference(ndev->npinfo);
567	if (!npinfo) {
568		npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL);
569		if (!npinfo) {
570			err = -ENOMEM;
571			goto out;
572		}
573
574		sema_init(&npinfo->dev_lock, 1);
575		skb_queue_head_init(&npinfo->txq);
576		INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
577
578		refcount_set(&npinfo->refcnt, 1);
579
580		ops = ndev->netdev_ops;
581		if (ops->ndo_netpoll_setup) {
582			err = ops->ndo_netpoll_setup(ndev);
583			if (err)
584				goto free_npinfo;
585		}
586	} else {
587		refcount_inc(&npinfo->refcnt);
588	}
589
590	np->dev = ndev;
591	strscpy(np->dev_name, ndev->name, IFNAMSIZ);
592
593	/* fill up the skb queue */
594	refill_skbs(np);
595
596	/* last thing to do is link it to the net device structure */
597	rcu_assign_pointer(ndev->npinfo, npinfo);
598
599	return 0;
600
601free_npinfo:
602	kfree(npinfo);
603out:
604	return err;
605}
606EXPORT_SYMBOL_GPL(__netpoll_setup);
607
608/*
609 * Returns a pointer to a string representation of the identifier used
610 * to select the egress interface for the given netpoll instance. buf
611 * must be a buffer of length at least MAC_ADDR_STR_LEN + 1.
612 */
613static char *egress_dev(struct netpoll *np, char *buf)
614{
615	if (np->dev_name[0])
616		return np->dev_name;
617
618	snprintf(buf, MAC_ADDR_STR_LEN, "%pM", np->dev_mac);
619	return buf;
620}
621
622static void netpoll_wait_carrier(struct netpoll *np, struct net_device *ndev,
623				 unsigned int timeout)
624{
625	unsigned long atmost;
626
627	atmost = jiffies + timeout * HZ;
628	while (!netif_carrier_ok(ndev)) {
629		if (time_after(jiffies, atmost)) {
630			np_notice(np, "timeout waiting for carrier\n");
631			break;
632		}
633		msleep(1);
634	}
635}
636
637/*
638 * Take the IPv6 from ndev and populate local_ip structure in netpoll
639 */
640static int netpoll_take_ipv6(struct netpoll *np, struct net_device *ndev)
641{
642	char buf[MAC_ADDR_STR_LEN + 1];
643	int err = -EDESTADDRREQ;
644	struct inet6_dev *idev;
645
646	if (!IS_ENABLED(CONFIG_IPV6)) {
647		np_err(np, "IPv6 is not supported %s, aborting\n",
648		       egress_dev(np, buf));
649		return -EINVAL;
650	}
651
652	idev = __in6_dev_get(ndev);
653	if (idev) {
654		struct inet6_ifaddr *ifp;
655
656		read_lock_bh(&idev->lock);
657		list_for_each_entry(ifp, &idev->addr_list, if_list) {
658			if (!!(ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL) !=
659				!!(ipv6_addr_type(&np->remote_ip.in6) & IPV6_ADDR_LINKLOCAL))
660				continue;
661			/* Got the IP, let's return */
662			np->local_ip.in6 = ifp->addr;
663			err = 0;
664			break;
665		}
666		read_unlock_bh(&idev->lock);
667	}
668	if (err) {
669		np_err(np, "no IPv6 address for %s, aborting\n",
670		       egress_dev(np, buf));
671		return err;
672	}
673
674	np_info(np, "local IPv6 %pI6c\n", &np->local_ip.in6);
675	return 0;
676}
677
678/*
679 * Take the IPv4 from ndev and populate local_ip structure in netpoll
680 */
681static int netpoll_take_ipv4(struct netpoll *np, struct net_device *ndev)
682{
683	char buf[MAC_ADDR_STR_LEN + 1];
684	const struct in_ifaddr *ifa;
685	struct in_device *in_dev;
686
687	in_dev = __in_dev_get_rtnl(ndev);
688	if (!in_dev) {
689		np_err(np, "no IP address for %s, aborting\n",
690		       egress_dev(np, buf));
691		return -EDESTADDRREQ;
692	}
693
694	ifa = rtnl_dereference(in_dev->ifa_list);
695	if (!ifa) {
696		np_err(np, "no IP address for %s, aborting\n",
697		       egress_dev(np, buf));
698		return -EDESTADDRREQ;
699	}
700
701	np->local_ip.ip = ifa->ifa_local;
702	np_info(np, "local IP %pI4\n", &np->local_ip.ip);
703
704	return 0;
705}
706
707int netpoll_setup(struct netpoll *np)
708{
709	struct net *net = current->nsproxy->net_ns;
710	char buf[MAC_ADDR_STR_LEN + 1];
711	struct net_device *ndev = NULL;
712	bool ip_overwritten = false;
713	int err;
714
715	rtnl_lock();
716	if (np->dev_name[0])
717		ndev = __dev_get_by_name(net, np->dev_name);
718	else if (is_valid_ether_addr(np->dev_mac))
719		ndev = dev_getbyhwaddr(net, ARPHRD_ETHER, np->dev_mac);
720
721	if (!ndev) {
722		np_err(np, "%s doesn't exist, aborting\n", egress_dev(np, buf));
723		err = -ENODEV;
724		goto unlock;
725	}
726	netdev_hold(ndev, &np->dev_tracker, GFP_KERNEL);
727
728	if (netdev_master_upper_dev_get(ndev)) {
729		np_err(np, "%s is a slave device, aborting\n",
730		       egress_dev(np, buf));
731		err = -EBUSY;
732		goto put;
733	}
734
735	if (!netif_running(ndev)) {
736		np_info(np, "device %s not up yet, forcing it\n",
737			egress_dev(np, buf));
738
739		err = dev_open(ndev, NULL);
740		if (err) {
741			np_err(np, "failed to open %s\n", ndev->name);
742			goto put;
743		}
744
745		rtnl_unlock();
746		netpoll_wait_carrier(np, ndev, carrier_timeout);
747		rtnl_lock();
748	}
749
750	if (!np->local_ip.ip) {
751		if (!np->ipv6) {
752			err = netpoll_take_ipv4(np, ndev);
753			if (err)
754				goto put;
755		} else {
756			err = netpoll_take_ipv6(np, ndev);
757			if (err)
758				goto put;
759		}
760		ip_overwritten = true;
761	}
762
763	err = __netpoll_setup(np, ndev);
764	if (err)
765		goto flush;
766	rtnl_unlock();
767
768	/* Make sure all NAPI polls which started before dev->npinfo
769	 * was visible have exited before we start calling NAPI poll.
770	 * NAPI skips locking if dev->npinfo is NULL.
771	 */
772	synchronize_rcu();
773
774	return 0;
775
776flush:
777	skb_pool_flush(np);
778put:
779	DEBUG_NET_WARN_ON_ONCE(np->dev);
780	if (ip_overwritten)
781		memset(&np->local_ip, 0, sizeof(np->local_ip));
782	netdev_put(ndev, &np->dev_tracker);
783unlock:
784	rtnl_unlock();
785	return err;
786}
787EXPORT_SYMBOL(netpoll_setup);
788
789static void rcu_cleanup_netpoll_info(struct rcu_head *rcu_head)
790{
791	struct netpoll_info *npinfo =
792			container_of(rcu_head, struct netpoll_info, rcu);
793
794	skb_queue_purge(&npinfo->txq);
795
796	/* we can't call cancel_delayed_work_sync here, as we are in softirq */
797	cancel_delayed_work(&npinfo->tx_work);
798
799	/* clean after last, unfinished work */
800	__skb_queue_purge(&npinfo->txq);
801	/* now cancel it again */
802	cancel_delayed_work(&npinfo->tx_work);
803	kfree(npinfo);
804}
805
806static void __netpoll_cleanup(struct netpoll *np)
807{
808	struct netpoll_info *npinfo;
809
810	npinfo = rtnl_dereference(np->dev->npinfo);
811	if (!npinfo)
812		return;
813
814	/* At this point, there is a single npinfo instance per netdevice, and
815	 * its refcnt tracks how many netpoll structures are linked to it. We
816	 * only perform npinfo cleanup when the refcnt decrements to zero.
817	 */
818	if (refcount_dec_and_test(&npinfo->refcnt)) {
819		const struct net_device_ops *ops;
820
821		ops = np->dev->netdev_ops;
822		if (ops->ndo_netpoll_cleanup)
823			ops->ndo_netpoll_cleanup(np->dev);
824
825		RCU_INIT_POINTER(np->dev->npinfo, NULL);
826		call_rcu(&npinfo->rcu, rcu_cleanup_netpoll_info);
827	}
828
829	skb_pool_flush(np);
830}
831
832void __netpoll_free(struct netpoll *np)
833{
834	ASSERT_RTNL();
835
836	/* Wait for transmitting packets to finish before freeing. */
837	synchronize_net();
838	__netpoll_cleanup(np);
839	kfree(np);
840}
841EXPORT_SYMBOL_GPL(__netpoll_free);
842
843void do_netpoll_cleanup(struct netpoll *np)
844{
845	__netpoll_cleanup(np);
846	netdev_put(np->dev, &np->dev_tracker);
847	np->dev = NULL;
848}
849EXPORT_SYMBOL(do_netpoll_cleanup);
850
851void netpoll_cleanup(struct netpoll *np)
852{
853	rtnl_lock();
854	if (!np->dev)
855		goto out;
856	do_netpoll_cleanup(np);
857out:
858	rtnl_unlock();
859}
860EXPORT_SYMBOL(netpoll_cleanup);