netconsole.c revision d5123480b1d6f7d1a5fe1a13520cef88fb5d4c84 
1/*
2 *  linux/drivers/net/netconsole.c
3 *
4 *  Copyright (C) 2001  Ingo Molnar <mingo@redhat.com>
5 *
6 *  This file contains the implementation of an IRQ-safe, crash-safe
7 *  kernel console implementation that outputs kernel messages to the
8 *  network.
9 *
10 * Modification history:
11 *
12 * 2001-09-17    started by Ingo Molnar.
13 * 2003-08-11    2.6 port by Matt Mackall
14 *               simplified options
15 *               generic card hooks
16 *               works non-modular
17 * 2003-09-07    rewritten with netpoll api
18 */
19
20/****************************************************************
21 *      This program is free software; you can redistribute it and/or modify
22 *      it under the terms of the GNU General Public License as published by
23 *      the Free Software Foundation; either version 2, or (at your option)
24 *      any later version.
25 *
26 *      This program is distributed in the hope that it will be useful,
27 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
28 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
29 *      GNU General Public License for more details.
30 *
31 *      You should have received a copy of the GNU General Public License
32 *      along with this program; if not, write to the Free Software
33 *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
34 *
35 ****************************************************************/
36
37#include <linux/mm.h>
38#include <linux/init.h>
39#include <linux/module.h>
40#include <linux/slab.h>
41#include <linux/console.h>
42#include <linux/moduleparam.h>
43#include <linux/string.h>
44#include <linux/netpoll.h>
45#include <linux/inet.h>
46#include <linux/configfs.h>
47
48MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
49MODULE_DESCRIPTION("Console driver for network interfaces");
50MODULE_LICENSE("GPL");
51
52#define MAX_PARAM_LENGTH	256
53#define MAX_PRINT_CHUNK		1000
54
55static char config[MAX_PARAM_LENGTH];
56module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
57MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
58
59#ifndef	MODULE
60static int __init option_setup(char *opt)
61{
62	strlcpy(config, opt, MAX_PARAM_LENGTH);
63	return 1;
64}
65__setup("netconsole=", option_setup);
66#endif	/* MODULE */
67
68/* Linked list of all configured targets */
69static LIST_HEAD(target_list);
70
71/* This needs to be a spinlock because write_msg() cannot sleep */
72static DEFINE_SPINLOCK(target_list_lock);
73
74/**
75 * struct netconsole_target - Represents a configured netconsole target.
76 * @list:	Links this target into the target_list.
77 * @item:	Links us into the configfs subsystem hierarchy.
78 * @enabled:	On / off knob to enable / disable target.
79 *		Visible from userspace (read-write).
80 *		We maintain a strict 1:1 correspondence between this and
81 *		whether the corresponding netpoll is active or inactive.
82 *		Also, other parameters of a target may be modified at
83 *		runtime only when it is disabled (enabled == 0).
84 * @np:		The netpoll structure for this target.
85 *		Contains the other userspace visible parameters:
86 *		dev_name	(read-write)
87 *		local_port	(read-write)
88 *		remote_port	(read-write)
89 *		local_ip	(read-write)
90 *		remote_ip	(read-write)
91 *		local_mac	(read-only)
92 *		remote_mac	(read-write)
93 */
94struct netconsole_target {
95	struct list_head	list;
96#ifdef	CONFIG_NETCONSOLE_DYNAMIC
97	struct config_item	item;
98#endif
99	int			enabled;
100	struct netpoll		np;
101};
102
103#ifdef	CONFIG_NETCONSOLE_DYNAMIC
104
105static struct configfs_subsystem netconsole_subsys;
106
107static int __init dynamic_netconsole_init(void)
108{
109	config_group_init(&netconsole_subsys.su_group);
110	mutex_init(&netconsole_subsys.su_mutex);
111	return configfs_register_subsystem(&netconsole_subsys);
112}
113
114static void __exit dynamic_netconsole_exit(void)
115{
116	configfs_unregister_subsystem(&netconsole_subsys);
117}
118
119/*
120 * Targets that were created by parsing the boot/module option string
121 * do not exist in the configfs hierarchy (and have NULL names) and will
122 * never go away, so make these a no-op for them.
123 */
124static void netconsole_target_get(struct netconsole_target *nt)
125{
126	if (config_item_name(&nt->item))
127		config_item_get(&nt->item);
128}
129
130static void netconsole_target_put(struct netconsole_target *nt)
131{
132	if (config_item_name(&nt->item))
133		config_item_put(&nt->item);
134}
135
136#else	/* !CONFIG_NETCONSOLE_DYNAMIC */
137
138static int __init dynamic_netconsole_init(void)
139{
140	return 0;
141}
142
143static void __exit dynamic_netconsole_exit(void)
144{
145}
146
147/*
148 * No danger of targets going away from under us when dynamic
149 * reconfigurability is off.
150 */
151static void netconsole_target_get(struct netconsole_target *nt)
152{
153}
154
155static void netconsole_target_put(struct netconsole_target *nt)
156{
157}
158
159#endif	/* CONFIG_NETCONSOLE_DYNAMIC */
160
161/* Allocate new target (from boot/module param) and setup netpoll for it */
162static struct netconsole_target *alloc_param_target(char *target_config)
163{
164	int err = -ENOMEM;
165	struct netconsole_target *nt;
166
167	/*
168	 * Allocate and initialize with defaults.
169	 * Note that these targets get their config_item fields zeroed-out.
170	 */
171	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
172	if (!nt) {
173		printk(KERN_ERR "netconsole: failed to allocate memory\n");
174		goto fail;
175	}
176
177	nt->np.name = "netconsole";
178	strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
179	nt->np.local_port = 6665;
180	nt->np.remote_port = 6666;
181	memset(nt->np.remote_mac, 0xff, ETH_ALEN);
182
183	/* Parse parameters and setup netpoll */
184	err = netpoll_parse_options(&nt->np, target_config);
185	if (err)
186		goto fail;
187
188	err = netpoll_setup(&nt->np);
189	if (err)
190		goto fail;
191
192	nt->enabled = 1;
193
194	return nt;
195
196fail:
197	kfree(nt);
198	return ERR_PTR(err);
199}
200
201/* Cleanup netpoll for given target (from boot/module param) and free it */
202static void free_param_target(struct netconsole_target *nt)
203{
204	netpoll_cleanup(&nt->np);
205	kfree(nt);
206}
207
208#ifdef	CONFIG_NETCONSOLE_DYNAMIC
209
210/*
211 * Our subsystem hierarchy is:
212 *
213 * /sys/kernel/config/netconsole/
214 *				|
215 *				<target>/
216 *				|	enabled
217 *				|	dev_name
218 *				|	local_port
219 *				|	remote_port
220 *				|	local_ip
221 *				|	remote_ip
222 *				|	local_mac
223 *				|	remote_mac
224 *				|
225 *				<target>/...
226 */
227
228struct netconsole_target_attr {
229	struct configfs_attribute	attr;
230	ssize_t				(*show)(struct netconsole_target *nt,
231						char *buf);
232	ssize_t				(*store)(struct netconsole_target *nt,
233						 const char *buf,
234						 size_t count);
235};
236
237static struct netconsole_target *to_target(struct config_item *item)
238{
239	return item ?
240		container_of(item, struct netconsole_target, item) :
241		NULL;
242}
243
244/*
245 * Attribute operations for netconsole_target.
246 */
247
248static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
249{
250	return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
251}
252
253static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
254{
255	return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
256}
257
258static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
259{
260	return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
261}
262
263static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
264{
265	return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
266}
267
268static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
269{
270	return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
271}
272
273static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
274{
275	return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
276}
277
278static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
279{
280	struct net_device *dev = nt->np.dev;
281	static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
282
283	return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
284}
285
286static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
287{
288	return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
289}
290
291/*
292 * This one is special -- targets created through the configfs interface
293 * are not enabled (and the corresponding netpoll activated) by default.
294 * The user is expected to set the desired parameters first (which
295 * would enable him to dynamically add new netpoll targets for new
296 * network interfaces as and when they come up).
297 */
298static ssize_t store_enabled(struct netconsole_target *nt,
299			     const char *buf,
300			     size_t count)
301{
302	int enabled;
303	int err;
304
305	err = kstrtoint(buf, 10, &enabled);
306	if (err < 0)
307		return err;
308	if (enabled < 0 || enabled > 1)
309		return -EINVAL;
310	if (enabled == nt->enabled) {
311		printk(KERN_INFO "netconsole: network logging has already %s\n",
312				nt->enabled ? "started" : "stopped");
313		return -EINVAL;
314	}
315
316	if (enabled) {	/* 1 */
317
318		/*
319		 * Skip netpoll_parse_options() -- all the attributes are
320		 * already configured via configfs. Just print them out.
321		 */
322		netpoll_print_options(&nt->np);
323
324		err = netpoll_setup(&nt->np);
325		if (err)
326			return err;
327
328		printk(KERN_INFO "netconsole: network logging started\n");
329
330	} else {	/* 0 */
331		netpoll_cleanup(&nt->np);
332	}
333
334	nt->enabled = enabled;
335
336	return strnlen(buf, count);
337}
338
339static ssize_t store_dev_name(struct netconsole_target *nt,
340			      const char *buf,
341			      size_t count)
342{
343	size_t len;
344
345	if (nt->enabled) {
346		printk(KERN_ERR "netconsole: target (%s) is enabled, "
347				"disable to update parameters\n",
348				config_item_name(&nt->item));
349		return -EINVAL;
350	}
351
352	strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
353
354	/* Get rid of possible trailing newline from echo(1) */
355	len = strnlen(nt->np.dev_name, IFNAMSIZ);
356	if (nt->np.dev_name[len - 1] == '\n')
357		nt->np.dev_name[len - 1] = '\0';
358
359	return strnlen(buf, count);
360}
361
362static ssize_t store_local_port(struct netconsole_target *nt,
363				const char *buf,
364				size_t count)
365{
366	int rv;
367
368	if (nt->enabled) {
369		printk(KERN_ERR "netconsole: target (%s) is enabled, "
370				"disable to update parameters\n",
371				config_item_name(&nt->item));
372		return -EINVAL;
373	}
374
375	rv = kstrtou16(buf, 10, &nt->np.local_port);
376	if (rv < 0)
377		return rv;
378	return strnlen(buf, count);
379}
380
381static ssize_t store_remote_port(struct netconsole_target *nt,
382				 const char *buf,
383				 size_t count)
384{
385	int rv;
386
387	if (nt->enabled) {
388		printk(KERN_ERR "netconsole: target (%s) is enabled, "
389				"disable to update parameters\n",
390				config_item_name(&nt->item));
391		return -EINVAL;
392	}
393
394	rv = kstrtou16(buf, 10, &nt->np.remote_port);
395	if (rv < 0)
396		return rv;
397	return strnlen(buf, count);
398}
399
400static ssize_t store_local_ip(struct netconsole_target *nt,
401			      const char *buf,
402			      size_t count)
403{
404	if (nt->enabled) {
405		printk(KERN_ERR "netconsole: target (%s) is enabled, "
406				"disable to update parameters\n",
407				config_item_name(&nt->item));
408		return -EINVAL;
409	}
410
411	nt->np.local_ip = in_aton(buf);
412
413	return strnlen(buf, count);
414}
415
416static ssize_t store_remote_ip(struct netconsole_target *nt,
417			       const char *buf,
418			       size_t count)
419{
420	if (nt->enabled) {
421		printk(KERN_ERR "netconsole: target (%s) is enabled, "
422				"disable to update parameters\n",
423				config_item_name(&nt->item));
424		return -EINVAL;
425	}
426
427	nt->np.remote_ip = in_aton(buf);
428
429	return strnlen(buf, count);
430}
431
432static ssize_t store_remote_mac(struct netconsole_target *nt,
433				const char *buf,
434				size_t count)
435{
436	u8 remote_mac[ETH_ALEN];
437
438	if (nt->enabled) {
439		printk(KERN_ERR "netconsole: target (%s) is enabled, "
440				"disable to update parameters\n",
441				config_item_name(&nt->item));
442		return -EINVAL;
443	}
444
445	if (!mac_pton(buf, remote_mac))
446		return -EINVAL;
447	if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
448		return -EINVAL;
449	memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
450
451	return strnlen(buf, count);
452}
453
454/*
455 * Attribute definitions for netconsole_target.
456 */
457
458#define NETCONSOLE_TARGET_ATTR_RO(_name)				\
459static struct netconsole_target_attr netconsole_target_##_name =	\
460	__CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
461
462#define NETCONSOLE_TARGET_ATTR_RW(_name)				\
463static struct netconsole_target_attr netconsole_target_##_name =	\
464	__CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
465
466NETCONSOLE_TARGET_ATTR_RW(enabled);
467NETCONSOLE_TARGET_ATTR_RW(dev_name);
468NETCONSOLE_TARGET_ATTR_RW(local_port);
469NETCONSOLE_TARGET_ATTR_RW(remote_port);
470NETCONSOLE_TARGET_ATTR_RW(local_ip);
471NETCONSOLE_TARGET_ATTR_RW(remote_ip);
472NETCONSOLE_TARGET_ATTR_RO(local_mac);
473NETCONSOLE_TARGET_ATTR_RW(remote_mac);
474
475static struct configfs_attribute *netconsole_target_attrs[] = {
476	&netconsole_target_enabled.attr,
477	&netconsole_target_dev_name.attr,
478	&netconsole_target_local_port.attr,
479	&netconsole_target_remote_port.attr,
480	&netconsole_target_local_ip.attr,
481	&netconsole_target_remote_ip.attr,
482	&netconsole_target_local_mac.attr,
483	&netconsole_target_remote_mac.attr,
484	NULL,
485};
486
487/*
488 * Item operations and type for netconsole_target.
489 */
490
491static void netconsole_target_release(struct config_item *item)
492{
493	kfree(to_target(item));
494}
495
496static ssize_t netconsole_target_attr_show(struct config_item *item,
497					   struct configfs_attribute *attr,
498					   char *buf)
499{
500	ssize_t ret = -EINVAL;
501	struct netconsole_target *nt = to_target(item);
502	struct netconsole_target_attr *na =
503		container_of(attr, struct netconsole_target_attr, attr);
504
505	if (na->show)
506		ret = na->show(nt, buf);
507
508	return ret;
509}
510
511static ssize_t netconsole_target_attr_store(struct config_item *item,
512					    struct configfs_attribute *attr,
513					    const char *buf,
514					    size_t count)
515{
516	ssize_t ret = -EINVAL;
517	struct netconsole_target *nt = to_target(item);
518	struct netconsole_target_attr *na =
519		container_of(attr, struct netconsole_target_attr, attr);
520
521	if (na->store)
522		ret = na->store(nt, buf, count);
523
524	return ret;
525}
526
527static struct configfs_item_operations netconsole_target_item_ops = {
528	.release		= netconsole_target_release,
529	.show_attribute		= netconsole_target_attr_show,
530	.store_attribute	= netconsole_target_attr_store,
531};
532
533static struct config_item_type netconsole_target_type = {
534	.ct_attrs		= netconsole_target_attrs,
535	.ct_item_ops		= &netconsole_target_item_ops,
536	.ct_owner		= THIS_MODULE,
537};
538
539/*
540 * Group operations and type for netconsole_subsys.
541 */
542
543static struct config_item *make_netconsole_target(struct config_group *group,
544						  const char *name)
545{
546	unsigned long flags;
547	struct netconsole_target *nt;
548
549	/*
550	 * Allocate and initialize with defaults.
551	 * Target is disabled at creation (enabled == 0).
552	 */
553	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
554	if (!nt) {
555		printk(KERN_ERR "netconsole: failed to allocate memory\n");
556		return ERR_PTR(-ENOMEM);
557	}
558
559	nt->np.name = "netconsole";
560	strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
561	nt->np.local_port = 6665;
562	nt->np.remote_port = 6666;
563	memset(nt->np.remote_mac, 0xff, ETH_ALEN);
564
565	/* Initialize the config_item member */
566	config_item_init_type_name(&nt->item, name, &netconsole_target_type);
567
568	/* Adding, but it is disabled */
569	spin_lock_irqsave(&target_list_lock, flags);
570	list_add(&nt->list, &target_list);
571	spin_unlock_irqrestore(&target_list_lock, flags);
572
573	return &nt->item;
574}
575
576static void drop_netconsole_target(struct config_group *group,
577				   struct config_item *item)
578{
579	unsigned long flags;
580	struct netconsole_target *nt = to_target(item);
581
582	spin_lock_irqsave(&target_list_lock, flags);
583	list_del(&nt->list);
584	spin_unlock_irqrestore(&target_list_lock, flags);
585
586	/*
587	 * The target may have never been enabled, or was manually disabled
588	 * before being removed so netpoll may have already been cleaned up.
589	 */
590	if (nt->enabled)
591		netpoll_cleanup(&nt->np);
592
593	config_item_put(&nt->item);
594}
595
596static struct configfs_group_operations netconsole_subsys_group_ops = {
597	.make_item	= make_netconsole_target,
598	.drop_item	= drop_netconsole_target,
599};
600
601static struct config_item_type netconsole_subsys_type = {
602	.ct_group_ops	= &netconsole_subsys_group_ops,
603	.ct_owner	= THIS_MODULE,
604};
605
606/* The netconsole configfs subsystem */
607static struct configfs_subsystem netconsole_subsys = {
608	.su_group	= {
609		.cg_item	= {
610			.ci_namebuf	= "netconsole",
611			.ci_type	= &netconsole_subsys_type,
612		},
613	},
614};
615
616#endif	/* CONFIG_NETCONSOLE_DYNAMIC */
617
618/* Handle network interface device notifications */
619static int netconsole_netdev_event(struct notifier_block *this,
620				   unsigned long event,
621				   void *ptr)
622{
623	unsigned long flags;
624	struct netconsole_target *nt;
625	struct net_device *dev = ptr;
626	bool stopped = false;
627
628	if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER ||
629	      event == NETDEV_RELEASE || event == NETDEV_JOIN))
630		goto done;
631
632	spin_lock_irqsave(&target_list_lock, flags);
633	list_for_each_entry(nt, &target_list, list) {
634		netconsole_target_get(nt);
635		if (nt->np.dev == dev) {
636			switch (event) {
637			case NETDEV_CHANGENAME:
638				strlcpy(nt->np.dev_name, dev->name, IFNAMSIZ);
639				break;
640			case NETDEV_RELEASE:
641			case NETDEV_JOIN:
642			case NETDEV_UNREGISTER:
643				/*
644				 * rtnl_lock already held
645				 */
646				if (nt->np.dev) {
647					spin_unlock_irqrestore(
648							      &target_list_lock,
649							      flags);
650					__netpoll_cleanup(&nt->np);
651					spin_lock_irqsave(&target_list_lock,
652							  flags);
653					dev_put(nt->np.dev);
654					nt->np.dev = NULL;
655					netconsole_target_put(nt);
656				}
657				nt->enabled = 0;
658				stopped = true;
659				break;
660			}
661		}
662		netconsole_target_put(nt);
663	}
664	spin_unlock_irqrestore(&target_list_lock, flags);
665	if (stopped) {
666		printk(KERN_INFO "netconsole: network logging stopped on "
667		       "interface %s as it ", dev->name);
668		switch (event) {
669		case NETDEV_UNREGISTER:
670			printk(KERN_CONT "unregistered\n");
671			break;
672		case NETDEV_RELEASE:
673			printk(KERN_CONT "released slaves\n");
674			break;
675		case NETDEV_JOIN:
676			printk(KERN_CONT "is joining a master device\n");
677			break;
678		}
679	}
680
681done:
682	return NOTIFY_DONE;
683}
684
685static struct notifier_block netconsole_netdev_notifier = {
686	.notifier_call  = netconsole_netdev_event,
687};
688
689static void write_msg(struct console *con, const char *msg, unsigned int len)
690{
691	int frag, left;
692	unsigned long flags;
693	struct netconsole_target *nt;
694	const char *tmp;
695
696	/* Avoid taking lock and disabling interrupts unnecessarily */
697	if (list_empty(&target_list))
698		return;
699
700	spin_lock_irqsave(&target_list_lock, flags);
701	list_for_each_entry(nt, &target_list, list) {
702		netconsole_target_get(nt);
703		if (nt->enabled && netif_running(nt->np.dev)) {
704			/*
705			 * We nest this inside the for-each-target loop above
706			 * so that we're able to get as much logging out to
707			 * at least one target if we die inside here, instead
708			 * of unnecessarily keeping all targets in lock-step.
709			 */
710			tmp = msg;
711			for (left = len; left;) {
712				frag = min(left, MAX_PRINT_CHUNK);
713				netpoll_send_udp(&nt->np, tmp, frag);
714				tmp += frag;
715				left -= frag;
716			}
717		}
718		netconsole_target_put(nt);
719	}
720	spin_unlock_irqrestore(&target_list_lock, flags);
721}
722
723static struct console netconsole = {
724	.name	= "netcon",
725	.flags	= CON_ENABLED,
726	.write	= write_msg,
727};
728
729static int __init init_netconsole(void)
730{
731	int err;
732	struct netconsole_target *nt, *tmp;
733	unsigned long flags;
734	char *target_config;
735	char *input = config;
736
737	if (strnlen(input, MAX_PARAM_LENGTH)) {
738		while ((target_config = strsep(&input, ";"))) {
739			nt = alloc_param_target(target_config);
740			if (IS_ERR(nt)) {
741				err = PTR_ERR(nt);
742				goto fail;
743			}
744			/* Dump existing printks when we register */
745			netconsole.flags |= CON_PRINTBUFFER;
746
747			spin_lock_irqsave(&target_list_lock, flags);
748			list_add(&nt->list, &target_list);
749			spin_unlock_irqrestore(&target_list_lock, flags);
750		}
751	}
752
753	err = register_netdevice_notifier(&netconsole_netdev_notifier);
754	if (err)
755		goto fail;
756
757	err = dynamic_netconsole_init();
758	if (err)
759		goto undonotifier;
760
761	register_console(&netconsole);
762	printk(KERN_INFO "netconsole: network logging started\n");
763
764	return err;
765
766undonotifier:
767	unregister_netdevice_notifier(&netconsole_netdev_notifier);
768
769fail:
770	printk(KERN_ERR "netconsole: cleaning up\n");
771
772	/*
773	 * Remove all targets and destroy them (only targets created
774	 * from the boot/module option exist here). Skipping the list
775	 * lock is safe here, and netpoll_cleanup() will sleep.
776	 */
777	list_for_each_entry_safe(nt, tmp, &target_list, list) {
778		list_del(&nt->list);
779		free_param_target(nt);
780	}
781
782	return err;
783}
784
785static void __exit cleanup_netconsole(void)
786{
787	struct netconsole_target *nt, *tmp;
788
789	unregister_console(&netconsole);
790	dynamic_netconsole_exit();
791	unregister_netdevice_notifier(&netconsole_netdev_notifier);
792
793	/*
794	 * Targets created via configfs pin references on our module
795	 * and would first be rmdir(2)'ed from userspace. We reach
796	 * here only when they are already destroyed, and only those
797	 * created from the boot/module option are left, so remove and
798	 * destroy them. Skipping the list lock is safe here, and
799	 * netpoll_cleanup() will sleep.
800	 */
801	list_for_each_entry_safe(nt, tmp, &target_list, list) {
802		list_del(&nt->list);
803		free_param_target(nt);
804	}
805}
806
807/*
808 * Use late_initcall to ensure netconsole is
809 * initialized after network device driver if built-in.
810 *
811 * late_initcall() and module_init() are identical if built as module.
812 */
813late_initcall(init_netconsole);
814module_exit(cleanup_netconsole);
815