xref: /linux/drivers/net/netconsole.c (revision 0d456bad36d42d16022be045c8a53ddbb59ee478)
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 
48 MODULE_AUTHOR("Maintainer: Matt Mackall <mpm@selenic.com>");
49 MODULE_DESCRIPTION("Console driver for network interfaces");
50 MODULE_LICENSE("GPL");
51 
52 #define MAX_PARAM_LENGTH	256
53 #define MAX_PRINT_CHUNK		1000
54 
55 static char config[MAX_PARAM_LENGTH];
56 module_param_string(netconsole, config, MAX_PARAM_LENGTH, 0);
57 MODULE_PARM_DESC(netconsole, " netconsole=[src-port]@[src-ip]/[dev],[tgt-port]@<tgt-ip>/[tgt-macaddr]");
58 
59 static bool oops_only = false;
60 module_param(oops_only, bool, 0600);
61 MODULE_PARM_DESC(oops_only, "Only log oops messages");
62 
63 #ifndef	MODULE
64 static int __init option_setup(char *opt)
65 {
66 	strlcpy(config, opt, MAX_PARAM_LENGTH);
67 	return 1;
68 }
69 __setup("netconsole=", option_setup);
70 #endif	/* MODULE */
71 
72 /* Linked list of all configured targets */
73 static LIST_HEAD(target_list);
74 
75 /* This needs to be a spinlock because write_msg() cannot sleep */
76 static DEFINE_SPINLOCK(target_list_lock);
77 
78 /**
79  * struct netconsole_target - Represents a configured netconsole target.
80  * @list:	Links this target into the target_list.
81  * @item:	Links us into the configfs subsystem hierarchy.
82  * @enabled:	On / off knob to enable / disable target.
83  *		Visible from userspace (read-write).
84  *		We maintain a strict 1:1 correspondence between this and
85  *		whether the corresponding netpoll is active or inactive.
86  *		Also, other parameters of a target may be modified at
87  *		runtime only when it is disabled (enabled == 0).
88  * @np:		The netpoll structure for this target.
89  *		Contains the other userspace visible parameters:
90  *		dev_name	(read-write)
91  *		local_port	(read-write)
92  *		remote_port	(read-write)
93  *		local_ip	(read-write)
94  *		remote_ip	(read-write)
95  *		local_mac	(read-only)
96  *		remote_mac	(read-write)
97  */
98 struct netconsole_target {
99 	struct list_head	list;
100 #ifdef	CONFIG_NETCONSOLE_DYNAMIC
101 	struct config_item	item;
102 #endif
103 	int			enabled;
104 	struct netpoll		np;
105 };
106 
107 #ifdef	CONFIG_NETCONSOLE_DYNAMIC
108 
109 static struct configfs_subsystem netconsole_subsys;
110 
111 static int __init dynamic_netconsole_init(void)
112 {
113 	config_group_init(&netconsole_subsys.su_group);
114 	mutex_init(&netconsole_subsys.su_mutex);
115 	return configfs_register_subsystem(&netconsole_subsys);
116 }
117 
118 static void __exit dynamic_netconsole_exit(void)
119 {
120 	configfs_unregister_subsystem(&netconsole_subsys);
121 }
122 
123 /*
124  * Targets that were created by parsing the boot/module option string
125  * do not exist in the configfs hierarchy (and have NULL names) and will
126  * never go away, so make these a no-op for them.
127  */
128 static void netconsole_target_get(struct netconsole_target *nt)
129 {
130 	if (config_item_name(&nt->item))
131 		config_item_get(&nt->item);
132 }
133 
134 static void netconsole_target_put(struct netconsole_target *nt)
135 {
136 	if (config_item_name(&nt->item))
137 		config_item_put(&nt->item);
138 }
139 
140 #else	/* !CONFIG_NETCONSOLE_DYNAMIC */
141 
142 static int __init dynamic_netconsole_init(void)
143 {
144 	return 0;
145 }
146 
147 static void __exit dynamic_netconsole_exit(void)
148 {
149 }
150 
151 /*
152  * No danger of targets going away from under us when dynamic
153  * reconfigurability is off.
154  */
155 static void netconsole_target_get(struct netconsole_target *nt)
156 {
157 }
158 
159 static void netconsole_target_put(struct netconsole_target *nt)
160 {
161 }
162 
163 #endif	/* CONFIG_NETCONSOLE_DYNAMIC */
164 
165 /* Allocate new target (from boot/module param) and setup netpoll for it */
166 static struct netconsole_target *alloc_param_target(char *target_config)
167 {
168 	int err = -ENOMEM;
169 	struct netconsole_target *nt;
170 
171 	/*
172 	 * Allocate and initialize with defaults.
173 	 * Note that these targets get their config_item fields zeroed-out.
174 	 */
175 	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
176 	if (!nt)
177 		goto fail;
178 
179 	nt->np.name = "netconsole";
180 	strlcpy(nt->np.dev_name, "eth0", IFNAMSIZ);
181 	nt->np.local_port = 6665;
182 	nt->np.remote_port = 6666;
183 	memset(nt->np.remote_mac, 0xff, ETH_ALEN);
184 
185 	/* Parse parameters and setup netpoll */
186 	err = netpoll_parse_options(&nt->np, target_config);
187 	if (err)
188 		goto fail;
189 
190 	err = netpoll_setup(&nt->np);
191 	if (err)
192 		goto fail;
193 
194 	nt->enabled = 1;
195 
196 	return nt;
197 
198 fail:
199 	kfree(nt);
200 	return ERR_PTR(err);
201 }
202 
203 /* Cleanup netpoll for given target (from boot/module param) and free it */
204 static void free_param_target(struct netconsole_target *nt)
205 {
206 	netpoll_cleanup(&nt->np);
207 	kfree(nt);
208 }
209 
210 #ifdef	CONFIG_NETCONSOLE_DYNAMIC
211 
212 /*
213  * Our subsystem hierarchy is:
214  *
215  * /sys/kernel/config/netconsole/
216  *				|
217  *				<target>/
218  *				|	enabled
219  *				|	dev_name
220  *				|	local_port
221  *				|	remote_port
222  *				|	local_ip
223  *				|	remote_ip
224  *				|	local_mac
225  *				|	remote_mac
226  *				|
227  *				<target>/...
228  */
229 
230 struct netconsole_target_attr {
231 	struct configfs_attribute	attr;
232 	ssize_t				(*show)(struct netconsole_target *nt,
233 						char *buf);
234 	ssize_t				(*store)(struct netconsole_target *nt,
235 						 const char *buf,
236 						 size_t count);
237 };
238 
239 static struct netconsole_target *to_target(struct config_item *item)
240 {
241 	return item ?
242 		container_of(item, struct netconsole_target, item) :
243 		NULL;
244 }
245 
246 /*
247  * Attribute operations for netconsole_target.
248  */
249 
250 static ssize_t show_enabled(struct netconsole_target *nt, char *buf)
251 {
252 	return snprintf(buf, PAGE_SIZE, "%d\n", nt->enabled);
253 }
254 
255 static ssize_t show_dev_name(struct netconsole_target *nt, char *buf)
256 {
257 	return snprintf(buf, PAGE_SIZE, "%s\n", nt->np.dev_name);
258 }
259 
260 static ssize_t show_local_port(struct netconsole_target *nt, char *buf)
261 {
262 	return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.local_port);
263 }
264 
265 static ssize_t show_remote_port(struct netconsole_target *nt, char *buf)
266 {
267 	return snprintf(buf, PAGE_SIZE, "%d\n", nt->np.remote_port);
268 }
269 
270 static ssize_t show_local_ip(struct netconsole_target *nt, char *buf)
271 {
272 	return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.local_ip);
273 }
274 
275 static ssize_t show_remote_ip(struct netconsole_target *nt, char *buf)
276 {
277 	return snprintf(buf, PAGE_SIZE, "%pI4\n", &nt->np.remote_ip);
278 }
279 
280 static ssize_t show_local_mac(struct netconsole_target *nt, char *buf)
281 {
282 	struct net_device *dev = nt->np.dev;
283 	static const u8 bcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
284 
285 	return snprintf(buf, PAGE_SIZE, "%pM\n", dev ? dev->dev_addr : bcast);
286 }
287 
288 static ssize_t show_remote_mac(struct netconsole_target *nt, char *buf)
289 {
290 	return snprintf(buf, PAGE_SIZE, "%pM\n", nt->np.remote_mac);
291 }
292 
293 /*
294  * This one is special -- targets created through the configfs interface
295  * are not enabled (and the corresponding netpoll activated) by default.
296  * The user is expected to set the desired parameters first (which
297  * would enable him to dynamically add new netpoll targets for new
298  * network interfaces as and when they come up).
299  */
300 static ssize_t store_enabled(struct netconsole_target *nt,
301 			     const char *buf,
302 			     size_t count)
303 {
304 	int enabled;
305 	int err;
306 
307 	err = kstrtoint(buf, 10, &enabled);
308 	if (err < 0)
309 		return err;
310 	if (enabled < 0 || enabled > 1)
311 		return -EINVAL;
312 	if (enabled == nt->enabled) {
313 		printk(KERN_INFO "netconsole: network logging has already %s\n",
314 				nt->enabled ? "started" : "stopped");
315 		return -EINVAL;
316 	}
317 
318 	if (enabled) {	/* 1 */
319 
320 		/*
321 		 * Skip netpoll_parse_options() -- all the attributes are
322 		 * already configured via configfs. Just print them out.
323 		 */
324 		netpoll_print_options(&nt->np);
325 
326 		err = netpoll_setup(&nt->np);
327 		if (err)
328 			return err;
329 
330 		printk(KERN_INFO "netconsole: network logging started\n");
331 
332 	} else {	/* 0 */
333 		netpoll_cleanup(&nt->np);
334 	}
335 
336 	nt->enabled = enabled;
337 
338 	return strnlen(buf, count);
339 }
340 
341 static ssize_t store_dev_name(struct netconsole_target *nt,
342 			      const char *buf,
343 			      size_t count)
344 {
345 	size_t len;
346 
347 	if (nt->enabled) {
348 		printk(KERN_ERR "netconsole: target (%s) is enabled, "
349 				"disable to update parameters\n",
350 				config_item_name(&nt->item));
351 		return -EINVAL;
352 	}
353 
354 	strlcpy(nt->np.dev_name, buf, IFNAMSIZ);
355 
356 	/* Get rid of possible trailing newline from echo(1) */
357 	len = strnlen(nt->np.dev_name, IFNAMSIZ);
358 	if (nt->np.dev_name[len - 1] == '\n')
359 		nt->np.dev_name[len - 1] = '\0';
360 
361 	return strnlen(buf, count);
362 }
363 
364 static ssize_t store_local_port(struct netconsole_target *nt,
365 				const char *buf,
366 				size_t count)
367 {
368 	int rv;
369 
370 	if (nt->enabled) {
371 		printk(KERN_ERR "netconsole: target (%s) is enabled, "
372 				"disable to update parameters\n",
373 				config_item_name(&nt->item));
374 		return -EINVAL;
375 	}
376 
377 	rv = kstrtou16(buf, 10, &nt->np.local_port);
378 	if (rv < 0)
379 		return rv;
380 	return strnlen(buf, count);
381 }
382 
383 static ssize_t store_remote_port(struct netconsole_target *nt,
384 				 const char *buf,
385 				 size_t count)
386 {
387 	int rv;
388 
389 	if (nt->enabled) {
390 		printk(KERN_ERR "netconsole: target (%s) is enabled, "
391 				"disable to update parameters\n",
392 				config_item_name(&nt->item));
393 		return -EINVAL;
394 	}
395 
396 	rv = kstrtou16(buf, 10, &nt->np.remote_port);
397 	if (rv < 0)
398 		return rv;
399 	return strnlen(buf, count);
400 }
401 
402 static ssize_t store_local_ip(struct netconsole_target *nt,
403 			      const char *buf,
404 			      size_t count)
405 {
406 	if (nt->enabled) {
407 		printk(KERN_ERR "netconsole: target (%s) is enabled, "
408 				"disable to update parameters\n",
409 				config_item_name(&nt->item));
410 		return -EINVAL;
411 	}
412 
413 	nt->np.local_ip = in_aton(buf);
414 
415 	return strnlen(buf, count);
416 }
417 
418 static ssize_t store_remote_ip(struct netconsole_target *nt,
419 			       const char *buf,
420 			       size_t count)
421 {
422 	if (nt->enabled) {
423 		printk(KERN_ERR "netconsole: target (%s) is enabled, "
424 				"disable to update parameters\n",
425 				config_item_name(&nt->item));
426 		return -EINVAL;
427 	}
428 
429 	nt->np.remote_ip = in_aton(buf);
430 
431 	return strnlen(buf, count);
432 }
433 
434 static ssize_t store_remote_mac(struct netconsole_target *nt,
435 				const char *buf,
436 				size_t count)
437 {
438 	u8 remote_mac[ETH_ALEN];
439 
440 	if (nt->enabled) {
441 		printk(KERN_ERR "netconsole: target (%s) is enabled, "
442 				"disable to update parameters\n",
443 				config_item_name(&nt->item));
444 		return -EINVAL;
445 	}
446 
447 	if (!mac_pton(buf, remote_mac))
448 		return -EINVAL;
449 	if (buf[3 * ETH_ALEN - 1] && buf[3 * ETH_ALEN - 1] != '\n')
450 		return -EINVAL;
451 	memcpy(nt->np.remote_mac, remote_mac, ETH_ALEN);
452 
453 	return strnlen(buf, count);
454 }
455 
456 /*
457  * Attribute definitions for netconsole_target.
458  */
459 
460 #define NETCONSOLE_TARGET_ATTR_RO(_name)				\
461 static struct netconsole_target_attr netconsole_target_##_name =	\
462 	__CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
463 
464 #define NETCONSOLE_TARGET_ATTR_RW(_name)				\
465 static struct netconsole_target_attr netconsole_target_##_name =	\
466 	__CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)
467 
468 NETCONSOLE_TARGET_ATTR_RW(enabled);
469 NETCONSOLE_TARGET_ATTR_RW(dev_name);
470 NETCONSOLE_TARGET_ATTR_RW(local_port);
471 NETCONSOLE_TARGET_ATTR_RW(remote_port);
472 NETCONSOLE_TARGET_ATTR_RW(local_ip);
473 NETCONSOLE_TARGET_ATTR_RW(remote_ip);
474 NETCONSOLE_TARGET_ATTR_RO(local_mac);
475 NETCONSOLE_TARGET_ATTR_RW(remote_mac);
476 
477 static struct configfs_attribute *netconsole_target_attrs[] = {
478 	&netconsole_target_enabled.attr,
479 	&netconsole_target_dev_name.attr,
480 	&netconsole_target_local_port.attr,
481 	&netconsole_target_remote_port.attr,
482 	&netconsole_target_local_ip.attr,
483 	&netconsole_target_remote_ip.attr,
484 	&netconsole_target_local_mac.attr,
485 	&netconsole_target_remote_mac.attr,
486 	NULL,
487 };
488 
489 /*
490  * Item operations and type for netconsole_target.
491  */
492 
493 static void netconsole_target_release(struct config_item *item)
494 {
495 	kfree(to_target(item));
496 }
497 
498 static ssize_t netconsole_target_attr_show(struct config_item *item,
499 					   struct configfs_attribute *attr,
500 					   char *buf)
501 {
502 	ssize_t ret = -EINVAL;
503 	struct netconsole_target *nt = to_target(item);
504 	struct netconsole_target_attr *na =
505 		container_of(attr, struct netconsole_target_attr, attr);
506 
507 	if (na->show)
508 		ret = na->show(nt, buf);
509 
510 	return ret;
511 }
512 
513 static ssize_t netconsole_target_attr_store(struct config_item *item,
514 					    struct configfs_attribute *attr,
515 					    const char *buf,
516 					    size_t count)
517 {
518 	ssize_t ret = -EINVAL;
519 	struct netconsole_target *nt = to_target(item);
520 	struct netconsole_target_attr *na =
521 		container_of(attr, struct netconsole_target_attr, attr);
522 
523 	if (na->store)
524 		ret = na->store(nt, buf, count);
525 
526 	return ret;
527 }
528 
529 static struct configfs_item_operations netconsole_target_item_ops = {
530 	.release		= netconsole_target_release,
531 	.show_attribute		= netconsole_target_attr_show,
532 	.store_attribute	= netconsole_target_attr_store,
533 };
534 
535 static struct config_item_type netconsole_target_type = {
536 	.ct_attrs		= netconsole_target_attrs,
537 	.ct_item_ops		= &netconsole_target_item_ops,
538 	.ct_owner		= THIS_MODULE,
539 };
540 
541 /*
542  * Group operations and type for netconsole_subsys.
543  */
544 
545 static struct config_item *make_netconsole_target(struct config_group *group,
546 						  const char *name)
547 {
548 	unsigned long flags;
549 	struct netconsole_target *nt;
550 
551 	/*
552 	 * Allocate and initialize with defaults.
553 	 * Target is disabled at creation (enabled == 0).
554 	 */
555 	nt = kzalloc(sizeof(*nt), GFP_KERNEL);
556 	if (!nt)
557 		return ERR_PTR(-ENOMEM);
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 
576 static 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 
596 static struct configfs_group_operations netconsole_subsys_group_ops = {
597 	.make_item	= make_netconsole_target,
598 	.drop_item	= drop_netconsole_target,
599 };
600 
601 static 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 */
607 static 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 */
619 static 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 					__netpoll_cleanup(&nt->np);
648 					dev_put(nt->np.dev);
649 					nt->np.dev = NULL;
650 				}
651 				nt->enabled = 0;
652 				stopped = true;
653 				break;
654 			}
655 		}
656 		netconsole_target_put(nt);
657 	}
658 	spin_unlock_irqrestore(&target_list_lock, flags);
659 	if (stopped) {
660 		printk(KERN_INFO "netconsole: network logging stopped on "
661 		       "interface %s as it ", dev->name);
662 		switch (event) {
663 		case NETDEV_UNREGISTER:
664 			printk(KERN_CONT "unregistered\n");
665 			break;
666 		case NETDEV_RELEASE:
667 			printk(KERN_CONT "released slaves\n");
668 			break;
669 		case NETDEV_JOIN:
670 			printk(KERN_CONT "is joining a master device\n");
671 			break;
672 		}
673 	}
674 
675 done:
676 	return NOTIFY_DONE;
677 }
678 
679 static struct notifier_block netconsole_netdev_notifier = {
680 	.notifier_call  = netconsole_netdev_event,
681 };
682 
683 static void write_msg(struct console *con, const char *msg, unsigned int len)
684 {
685 	int frag, left;
686 	unsigned long flags;
687 	struct netconsole_target *nt;
688 	const char *tmp;
689 
690 	if (oops_only && !oops_in_progress)
691 		return;
692 	/* Avoid taking lock and disabling interrupts unnecessarily */
693 	if (list_empty(&target_list))
694 		return;
695 
696 	spin_lock_irqsave(&target_list_lock, flags);
697 	list_for_each_entry(nt, &target_list, list) {
698 		netconsole_target_get(nt);
699 		if (nt->enabled && netif_running(nt->np.dev)) {
700 			/*
701 			 * We nest this inside the for-each-target loop above
702 			 * so that we're able to get as much logging out to
703 			 * at least one target if we die inside here, instead
704 			 * of unnecessarily keeping all targets in lock-step.
705 			 */
706 			tmp = msg;
707 			for (left = len; left;) {
708 				frag = min(left, MAX_PRINT_CHUNK);
709 				netpoll_send_udp(&nt->np, tmp, frag);
710 				tmp += frag;
711 				left -= frag;
712 			}
713 		}
714 		netconsole_target_put(nt);
715 	}
716 	spin_unlock_irqrestore(&target_list_lock, flags);
717 }
718 
719 static struct console netconsole = {
720 	.name	= "netcon",
721 	.flags	= CON_ENABLED,
722 	.write	= write_msg,
723 };
724 
725 static int __init init_netconsole(void)
726 {
727 	int err;
728 	struct netconsole_target *nt, *tmp;
729 	unsigned long flags;
730 	char *target_config;
731 	char *input = config;
732 
733 	if (strnlen(input, MAX_PARAM_LENGTH)) {
734 		while ((target_config = strsep(&input, ";"))) {
735 			nt = alloc_param_target(target_config);
736 			if (IS_ERR(nt)) {
737 				err = PTR_ERR(nt);
738 				goto fail;
739 			}
740 			/* Dump existing printks when we register */
741 			netconsole.flags |= CON_PRINTBUFFER;
742 
743 			spin_lock_irqsave(&target_list_lock, flags);
744 			list_add(&nt->list, &target_list);
745 			spin_unlock_irqrestore(&target_list_lock, flags);
746 		}
747 	}
748 
749 	err = register_netdevice_notifier(&netconsole_netdev_notifier);
750 	if (err)
751 		goto fail;
752 
753 	err = dynamic_netconsole_init();
754 	if (err)
755 		goto undonotifier;
756 
757 	register_console(&netconsole);
758 	printk(KERN_INFO "netconsole: network logging started\n");
759 
760 	return err;
761 
762 undonotifier:
763 	unregister_netdevice_notifier(&netconsole_netdev_notifier);
764 
765 fail:
766 	printk(KERN_ERR "netconsole: cleaning up\n");
767 
768 	/*
769 	 * Remove all targets and destroy them (only targets created
770 	 * from the boot/module option exist here). Skipping the list
771 	 * lock is safe here, and netpoll_cleanup() will sleep.
772 	 */
773 	list_for_each_entry_safe(nt, tmp, &target_list, list) {
774 		list_del(&nt->list);
775 		free_param_target(nt);
776 	}
777 
778 	return err;
779 }
780 
781 static void __exit cleanup_netconsole(void)
782 {
783 	struct netconsole_target *nt, *tmp;
784 
785 	unregister_console(&netconsole);
786 	dynamic_netconsole_exit();
787 	unregister_netdevice_notifier(&netconsole_netdev_notifier);
788 
789 	/*
790 	 * Targets created via configfs pin references on our module
791 	 * and would first be rmdir(2)'ed from userspace. We reach
792 	 * here only when they are already destroyed, and only those
793 	 * created from the boot/module option are left, so remove and
794 	 * destroy them. Skipping the list lock is safe here, and
795 	 * netpoll_cleanup() will sleep.
796 	 */
797 	list_for_each_entry_safe(nt, tmp, &target_list, list) {
798 		list_del(&nt->list);
799 		free_param_target(nt);
800 	}
801 }
802 
803 /*
804  * Use late_initcall to ensure netconsole is
805  * initialized after network device driver if built-in.
806  *
807  * late_initcall() and module_init() are identical if built as module.
808  */
809 late_initcall(init_netconsole);
810 module_exit(cleanup_netconsole);
811