xref: /dragonfly/sys/kern/kern_shutdown.c (revision 2e3ed54d)
1 /*-
2  * Copyright (c) 1986, 1988, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  * (c) UNIX System Laboratories, Inc.
5  * All or some portions of this file are derived from material licensed
6  * to the University of California by American Telephone and Telegraph
7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8  * the permission of UNIX System Laboratories, Inc.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *	@(#)kern_shutdown.c	8.3 (Berkeley) 1/21/94
39  * $FreeBSD: src/sys/kern/kern_shutdown.c,v 1.72.2.12 2002/02/21 19:15:10 dillon Exp $
40  * $DragonFly: src/sys/kern/kern_shutdown.c,v 1.23 2005/11/04 09:38:15 dillon Exp $
41  */
42 
43 #include "opt_ddb.h"
44 #include "opt_ddb_trace.h"
45 #include "opt_hw_wdog.h"
46 #include "opt_panic.h"
47 #include "opt_show_busybufs.h"
48 
49 #include <sys/param.h>
50 #include <sys/systm.h>
51 #include <sys/eventhandler.h>
52 #include <sys/buf.h>
53 #include <sys/disklabel.h>
54 #include <sys/reboot.h>
55 #include <sys/proc.h>
56 #include <sys/vnode.h>
57 #include <sys/kernel.h>
58 #include <sys/kthread.h>
59 #include <sys/malloc.h>
60 #include <sys/mount.h>
61 #include <sys/queue.h>
62 #include <sys/sysctl.h>
63 #include <sys/conf.h>
64 #include <sys/sysproto.h>
65 #include <sys/device.h>
66 #include <sys/cons.h>
67 #include <sys/thread2.h>
68 #include <sys/buf2.h>
69 
70 #include <machine/pcb.h>
71 #include <machine/clock.h>
72 #include <machine/md_var.h>
73 #include <machine/smp.h>		/* smp_active_mask, cpuid */
74 
75 #include <sys/signalvar.h>
76 
77 #ifndef PANIC_REBOOT_WAIT_TIME
78 #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
79 #endif
80 
81 /*
82  * Note that stdarg.h and the ANSI style va_start macro is used for both
83  * ANSI and traditional C compilers.  We use the machine version to stay
84  * within the confines of the kernel header files.
85  */
86 #include <machine/stdarg.h>
87 
88 #ifdef DDB
89 #ifdef DDB_UNATTENDED
90 int debugger_on_panic = 0;
91 #else
92 int debugger_on_panic = 1;
93 #endif
94 SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic, CTLFLAG_RW,
95 	&debugger_on_panic, 0, "Run debugger on kernel panic");
96 
97 extern void db_print_backtrace(void);
98 
99 #ifdef DDB_TRACE
100 int trace_on_panic = 1;
101 #else
102 int trace_on_panic = 0;
103 #endif
104 SYSCTL_INT(_debug, OID_AUTO, trace_on_panic, CTLFLAG_RW,
105 	&trace_on_panic, 0, "Print stack trace on kernel panic");
106 #endif
107 
108 static int sync_on_panic = 1;
109 SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RW,
110 	&sync_on_panic, 0, "Do a sync before rebooting from a panic");
111 
112 SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0, "Shutdown environment");
113 
114 #ifdef	HW_WDOG
115 /*
116  * If there is a hardware watchdog, point this at the function needed to
117  * hold it off.
118  * It's needed when the kernel needs to do some lengthy operations.
119  * e.g. in wd.c when dumping core.. It's most annoying to have
120  * your precious core-dump only half written because the wdog kicked in.
121  */
122 watchdog_tickle_fn wdog_tickler = NULL;
123 #endif	/* HW_WDOG */
124 
125 /*
126  * Variable panicstr contains argument to first call to panic; used as flag
127  * to indicate that the kernel has already called panic.
128  */
129 const char *panicstr;
130 
131 int dumping;				/* system is dumping */
132 #ifdef SMP
133 u_int panic_cpu_interlock;		/* panic interlock */
134 globaldata_t panic_cpu_gd;		/* which cpu took the panic */
135 #endif
136 
137 static void boot (int) __dead2;
138 static void dumpsys (void);
139 static int setdumpdev (dev_t dev);
140 static void poweroff_wait (void *, int);
141 static void print_uptime (void);
142 static void shutdown_halt (void *junk, int howto);
143 static void shutdown_panic (void *junk, int howto);
144 static void shutdown_reset (void *junk, int howto);
145 
146 /* register various local shutdown events */
147 static void
148 shutdown_conf(void *unused)
149 {
150 	EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL, SHUTDOWN_PRI_FIRST);
151 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL, SHUTDOWN_PRI_LAST + 100);
152 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL, SHUTDOWN_PRI_LAST + 100);
153 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL, SHUTDOWN_PRI_LAST + 200);
154 }
155 
156 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL)
157 
158 /* ARGSUSED */
159 
160 /*
161  * The system call that results in a reboot
162  */
163 int
164 reboot(struct reboot_args *uap)
165 {
166 	struct thread *td = curthread;
167 	int error;
168 
169 	if ((error = suser(td)))
170 		return (error);
171 
172 	boot(uap->opt);
173 	return (0);
174 }
175 
176 /*
177  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
178  */
179 static int shutdown_howto = 0;
180 
181 void
182 shutdown_nice(int howto)
183 {
184 	shutdown_howto = howto;
185 
186 	/* Send a signal to init(8) and have it shutdown the world */
187 	if (initproc != NULL) {
188 		psignal(initproc, SIGINT);
189 	} else {
190 		/* No init(8) running, so simply reboot */
191 		boot(RB_NOSYNC);
192 	}
193 	return;
194 }
195 static int	waittime = -1;
196 static struct pcb dumppcb;
197 
198 static void
199 print_uptime()
200 {
201 	int f;
202 	struct timespec ts;
203 
204 	getnanouptime(&ts);
205 	printf("Uptime: ");
206 	f = 0;
207 	if (ts.tv_sec >= 86400) {
208 		printf("%ldd", ts.tv_sec / 86400);
209 		ts.tv_sec %= 86400;
210 		f = 1;
211 	}
212 	if (f || ts.tv_sec >= 3600) {
213 		printf("%ldh", ts.tv_sec / 3600);
214 		ts.tv_sec %= 3600;
215 		f = 1;
216 	}
217 	if (f || ts.tv_sec >= 60) {
218 		printf("%ldm", ts.tv_sec / 60);
219 		ts.tv_sec %= 60;
220 		f = 1;
221 	}
222 	printf("%lds\n", ts.tv_sec);
223 }
224 
225 /*
226  *  Go through the rigmarole of shutting down..
227  * this used to be in machdep.c but I'll be dammned if I could see
228  * anything machine dependant in it.
229  */
230 static void
231 boot(int howto)
232 {
233 	/*
234 	 * Get rid of any user scheduler baggage and then give
235 	 * us a high priority.
236 	 */
237 	if (curthread->td_release)
238 		curthread->td_release(curthread);
239 	lwkt_setpri_self(TDPRI_MAX);
240 
241 	/* collect extra flags that shutdown_nice might have set */
242 	howto |= shutdown_howto;
243 
244 #ifdef SMP
245 	/*
246 	 * We really want to shutdown on the BSP.  Subsystems such as ACPI
247 	 * can't power-down the box otherwise.
248 	 */
249 	if (smp_active_mask > 1) {
250 		printf("boot() called on cpu#%d\n", mycpu->gd_cpuid);
251 	}
252 	if (panicstr == NULL && mycpu->gd_cpuid != 0) {
253 		printf("Switching to cpu #0 for shutdown\n");
254 		lwkt_setcpu_self(globaldata_find(0));
255 	}
256 #endif
257 	/*
258 	 * Do any callouts that should be done BEFORE syncing the filesystems.
259 	 */
260 	EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
261 
262 	/*
263 	 * Now sync filesystems
264 	 */
265 	if (!cold && (howto & RB_NOSYNC) == 0 && waittime < 0) {
266 		struct buf *bp;
267 		int iter, nbusy, pbusy;
268 
269 		waittime = 0;
270 		printf("\nsyncing disks... ");
271 
272 		sync(NULL);	/* YYY was sync(&proc0, NULL). why proc0 ? */
273 
274 		/*
275 		 * With soft updates, some buffers that are
276 		 * written will be remarked as dirty until other
277 		 * buffers are written.
278 		 */
279 		for (iter = pbusy = 0; iter < 20; iter++) {
280 			nbusy = 0;
281 			for (bp = &buf[nbuf]; --bp >= buf; ) {
282 				if ((bp->b_flags & B_INVAL) == 0 &&
283 				    BUF_REFCNT(bp) > 0) {
284 					nbusy++;
285 				} else if ((bp->b_flags & (B_DELWRI | B_INVAL))
286 						== B_DELWRI) {
287 					/* bawrite(bp);*/
288 					nbusy++;
289 				}
290 			}
291 			if (nbusy == 0)
292 				break;
293 			printf("%d ", nbusy);
294 			if (nbusy < pbusy)
295 				iter = 0;
296 			pbusy = nbusy;
297 			/*
298 			 * XXX:
299 			 * Process soft update work queue if buffers don't sync
300 			 * after 6 iterations by permitting the syncer to run.
301 			 */
302 			if (iter > 5 && bioops.io_sync)
303 				(*bioops.io_sync)(NULL);
304 			sync(NULL); /* YYY was sync(&proc0, NULL). why proc0 ? */
305 			tsleep(boot, 0, "shutdn", hz * iter / 20 + 1);
306 		}
307 		printf("\n");
308 		/*
309 		 * Count only busy local buffers to prevent forcing
310 		 * a fsck if we're just a client of a wedged NFS server
311 		 */
312 		nbusy = 0;
313 		for (bp = &buf[nbuf]; --bp >= buf; ) {
314 			if (((bp->b_flags&B_INVAL) == 0 && BUF_REFCNT(bp)) ||
315 			    ((bp->b_flags & (B_DELWRI|B_INVAL)) == B_DELWRI)) {
316 				if (bp->b_dev == NODEV) {
317 					mountlist_remove(bp->b_vp->v_mount);
318 					continue;
319 				}
320 				nbusy++;
321 #if defined(SHOW_BUSYBUFS) || defined(DIAGNOSTIC)
322 				printf(
323 			    "%p %d: dev:%s, flags:%08lx, blkno:%ld, lblkno:%ld\n",
324 				    bp, nbusy, devtoname(bp->b_dev),
325 				    bp->b_flags, (long)bp->b_blkno,
326 				    (long)bp->b_lblkno);
327 #endif
328 			}
329 		}
330 		if (nbusy) {
331 			/*
332 			 * Failed to sync all blocks. Indicate this and don't
333 			 * unmount filesystems (thus forcing an fsck on reboot).
334 			 */
335 			printf("giving up on %d buffers\n", nbusy);
336 #ifdef DDB
337 			Debugger("busy buffer problem");
338 #endif /* DDB */
339 			tsleep(boot, 0, "shutdn", hz * 5 + 1);
340 		} else {
341 			printf("done\n");
342 			/*
343 			 * Unmount filesystems
344 			 */
345 			if (panicstr == 0)
346 				vfs_unmountall();
347 		}
348 		tsleep(boot, 0, "shutdn", hz / 10 + 1);
349 	}
350 
351 	print_uptime();
352 
353 	/*
354 	 * Ok, now do things that assume all filesystem activity has
355 	 * been completed.
356 	 */
357 	EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
358 	crit_enter();
359 	if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold)
360 		dumpsys();
361 
362 	/* Now that we're going to really halt the system... */
363 	EVENTHANDLER_INVOKE(shutdown_final, howto);
364 
365 	for(;;) ;	/* safety against shutdown_reset not working */
366 	/* NOTREACHED */
367 }
368 
369 /*
370  * If the shutdown was a clean halt, behave accordingly.
371  */
372 static void
373 shutdown_halt(void *junk, int howto)
374 {
375 	if (howto & RB_HALT) {
376 		printf("\n");
377 		printf("The operating system has halted.\n");
378 		printf("Please press any key to reboot.\n\n");
379 		switch (cngetc()) {
380 		case -1:		/* No console, just die */
381 			cpu_halt();
382 			/* NOTREACHED */
383 		default:
384 			howto &= ~RB_HALT;
385 			break;
386 		}
387 	}
388 }
389 
390 /*
391  * Check to see if the system paniced, pause and then reboot
392  * according to the specified delay.
393  */
394 static void
395 shutdown_panic(void *junk, int howto)
396 {
397 	int loop;
398 
399 	if (howto & RB_DUMP) {
400 		if (PANIC_REBOOT_WAIT_TIME != 0) {
401 			if (PANIC_REBOOT_WAIT_TIME != -1) {
402 				printf("Automatic reboot in %d seconds - "
403 				       "press a key on the console to abort\n",
404 					PANIC_REBOOT_WAIT_TIME);
405 				for (loop = PANIC_REBOOT_WAIT_TIME * 10;
406 				     loop > 0; --loop) {
407 					DELAY(1000 * 100); /* 1/10th second */
408 					/* Did user type a key? */
409 					if (cncheckc() != -1)
410 						break;
411 				}
412 				if (!loop)
413 					return;
414 			}
415 		} else { /* zero time specified - reboot NOW */
416 			return;
417 		}
418 		printf("--> Press a key on the console to reboot,\n");
419 		printf("--> or switch off the system now.\n");
420 		cngetc();
421 	}
422 }
423 
424 /*
425  * Everything done, now reset
426  */
427 static void
428 shutdown_reset(void *junk, int howto)
429 {
430 	printf("Rebooting...\n");
431 	DELAY(1000000);	/* wait 1 sec for printf's to complete and be read */
432 	/* cpu_boot(howto); */ /* doesn't do anything at the moment */
433 	cpu_reset();
434 	/* NOTREACHED */ /* assuming reset worked */
435 }
436 
437 /*
438  * Magic number for savecore
439  *
440  * exported (symorder) and used at least by savecore(8)
441  *
442  */
443 static u_long const	dumpmag = 0x8fca0101UL;
444 
445 static int	dumpsize = 0;		/* also for savecore */
446 
447 static int	dodump = 1;
448 
449 SYSCTL_INT(_machdep, OID_AUTO, do_dump, CTLFLAG_RW, &dodump, 0,
450     "Try to perform coredump on kernel panic");
451 
452 static int
453 setdumpdev(dev)
454 	dev_t dev;
455 {
456 	int psize;
457 	long newdumplo;
458 
459 	if (dev == NODEV) {
460 		dumpdev = dev;
461 		return (0);
462 	}
463 	psize = dev_dpsize(dev);
464 	if (psize == -1)
465 		return (ENXIO);
466 	/*
467 	 * XXX should clean up checking in dumpsys() to be more like this.
468 	 */
469 	newdumplo = psize - Maxmem * (PAGE_SIZE / DEV_BSIZE);
470 	if (newdumplo <= LABELSECTOR)
471 		return (ENOSPC);
472 	dumpdev = dev;
473 	dumplo = newdumplo;
474 	return (0);
475 }
476 
477 
478 /* ARGSUSED */
479 static void dump_conf (void *dummy);
480 static void
481 dump_conf(dummy)
482 	void *dummy;
483 {
484 	char *path;
485 	dev_t dev;
486 
487 	path = malloc(MNAMELEN, M_TEMP, M_WAITOK);
488 	if (TUNABLE_STR_FETCH("dumpdev", path, MNAMELEN) != 0) {
489 		dev = getdiskbyname(path);
490 		if (dev != NODEV)
491 			dumpdev = dev;
492 	}
493 	free(path, M_TEMP);
494 	if (setdumpdev(dumpdev) != 0)
495 		dumpdev = NODEV;
496 }
497 
498 SYSINIT(dump_conf, SI_SUB_DUMP_CONF, SI_ORDER_FIRST, dump_conf, NULL)
499 
500 static int
501 sysctl_kern_dumpdev(SYSCTL_HANDLER_ARGS)
502 {
503 	int error;
504 	udev_t ndumpdev;
505 
506 	ndumpdev = dev2udev(dumpdev);
507 	error = sysctl_handle_opaque(oidp, &ndumpdev, sizeof ndumpdev, req);
508 	if (error == 0 && req->newptr != NULL)
509 		error = setdumpdev(udev2dev(ndumpdev, 0));
510 	return (error);
511 }
512 
513 SYSCTL_PROC(_kern, KERN_DUMPDEV, dumpdev, CTLTYPE_OPAQUE|CTLFLAG_RW,
514 	0, sizeof dumpdev, sysctl_kern_dumpdev, "T,dev_t", "");
515 
516 /*
517  * Doadump comes here after turning off memory management and
518  * getting on the dump stack, either when called above, or by
519  * the auto-restart code.
520  */
521 static void
522 dumpsys(void)
523 {
524 	int	error;
525 
526 	savectx(&dumppcb);
527 	if (dumping++) {
528 		printf("Dump already in progress, bailing...\n");
529 		return;
530 	}
531 	if (!dodump)
532 		return;
533 	if (dumpdev == NODEV)
534 		return;
535 	dumpsize = Maxmem;
536 	printf("\ndumping to dev %s, offset %ld\n", devtoname(dumpdev), dumplo);
537 	printf("dump ");
538 	error = dev_ddump(dumpdev);
539 	if (error == 0) {
540 		printf("succeeded\n");
541 		return;
542 	}
543 	printf("failed, reason: ");
544 	switch (error) {
545 	case ENOSYS:
546 	case ENODEV:
547 		printf("device doesn't support a dump routine\n");
548 		break;
549 
550 	case ENXIO:
551 		printf("device bad\n");
552 		break;
553 
554 	case EFAULT:
555 		printf("device not ready\n");
556 		break;
557 
558 	case EINVAL:
559 		printf("area improper\n");
560 		break;
561 
562 	case EIO:
563 		printf("i/o error\n");
564 		break;
565 
566 	case EINTR:
567 		printf("aborted from console\n");
568 		break;
569 
570 	default:
571 		printf("unknown, error = %d\n", error);
572 		break;
573 	}
574 }
575 
576 int
577 dumpstatus(vm_offset_t addr, off_t count)
578 {
579 	int c;
580 
581 	if (addr % (1024 * 1024) == 0) {
582 #ifdef HW_WDOG
583 		if (wdog_tickler)
584 			(*wdog_tickler)();
585 #endif
586 		printf("%ld ", (long)(count / (1024 * 1024)));
587 	}
588 
589 	if ((c = cncheckc()) == 0x03)
590 		return -1;
591 	else if (c != -1)
592 		printf("[CTRL-C to abort] ");
593 
594 	return 0;
595 }
596 
597 /*
598  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
599  * and then reboots.  If we are called twice, then we avoid trying to sync
600  * the disks as this often leads to recursive panics.
601  */
602 void
603 panic(const char *fmt, ...)
604 {
605 	int bootopt, newpanic;
606 	__va_list ap;
607 	static char buf[256];
608 
609 #ifdef SMP
610 	/*
611 	 * If a panic occurs on multiple cpus before the first is able to
612 	 * halt the other cpus, only one cpu is allowed to take the panic.
613 	 * Attempt to be verbose about this situation but if the printf()
614 	 * itself panics don't let us overrun the kernel stack.
615 	 *
616 	 * Be very nasty about descheduling our thread at the lowest
617 	 * level possible in an attempt to freeze the thread without
618 	 * inducing further panics.
619 	 *
620 	 * Bumping gd_trap_nesting_level will also bypass assertions in
621 	 * lwkt_switch() and allow us to switch away even if we are a
622 	 * FAST interrupt or IPI.
623 	 */
624 	if (atomic_poll_acquire_int(&panic_cpu_interlock)) {
625 		panic_cpu_gd = mycpu;
626 	} else if (panic_cpu_gd != mycpu) {
627 		crit_enter();
628 		++mycpu->gd_trap_nesting_level;
629 		if (mycpu->gd_trap_nesting_level < 25) {
630 			printf("SECONDARY PANIC ON CPU %d THREAD %p\n",
631 				mycpu->gd_cpuid, curthread);
632 		}
633 		curthread->td_release = NULL;	/* be a grinch */
634 		for (;;) {
635 			lwkt_deschedule_self(curthread);
636 			lwkt_switch();
637 		}
638 		/* NOT REACHED */
639 		/* --mycpu->gd_trap_nesting_level */
640 		/* crit_exit() */
641 	}
642 #endif
643 	bootopt = RB_AUTOBOOT | RB_DUMP;
644 	if (sync_on_panic == 0)
645 		bootopt |= RB_NOSYNC;
646 	newpanic = 0;
647 	if (panicstr)
648 		bootopt |= RB_NOSYNC;
649 	else {
650 		panicstr = fmt;
651 		newpanic = 1;
652 	}
653 
654 	__va_start(ap, fmt);
655 	(void)vsnprintf(buf, sizeof(buf), fmt, ap);
656 	if (panicstr == fmt)
657 		panicstr = buf;
658 	__va_end(ap);
659 	printf("panic: %s\n", buf);
660 #ifdef SMP
661 	/* three separate prints in case of an unmapped page and trap */
662 	printf("mp_lock = %08x; ", mp_lock);
663 	printf("cpuid = %d; ", mycpu->gd_cpuid);
664 	printf("lapic.id = %08x\n", lapic.id);
665 #endif
666 
667 #if defined(DDB)
668 	if (newpanic && trace_on_panic)
669 		db_print_backtrace();
670 	if (debugger_on_panic)
671 		Debugger ("panic");
672 #endif
673 	boot(bootopt);
674 }
675 
676 /*
677  * Support for poweroff delay.
678  */
679 #ifndef POWEROFF_DELAY
680 # define POWEROFF_DELAY 5000
681 #endif
682 static int poweroff_delay = POWEROFF_DELAY;
683 
684 SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
685 	&poweroff_delay, 0, "");
686 
687 static void
688 poweroff_wait(void *junk, int howto)
689 {
690 	if(!(howto & RB_POWEROFF) || poweroff_delay <= 0)
691 		return;
692 	DELAY(poweroff_delay * 1000);
693 }
694 
695 /*
696  * Some system processes (e.g. syncer) need to be stopped at appropriate
697  * points in their main loops prior to a system shutdown, so that they
698  * won't interfere with the shutdown process (e.g. by holding a disk buf
699  * to cause sync to fail).  For each of these system processes, register
700  * shutdown_kproc() as a handler for one of shutdown events.
701  */
702 static int kproc_shutdown_wait = 60;
703 SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
704     &kproc_shutdown_wait, 0, "");
705 
706 void
707 shutdown_kproc(void *arg, int howto)
708 {
709 	struct thread *td;
710 	struct proc *p;
711 	int error;
712 
713 	if (panicstr)
714 		return;
715 
716 	td = (struct thread *)arg;
717 	if ((p = td->td_proc) != NULL) {
718 	    printf("Waiting (max %d seconds) for system process `%s' to stop...",
719 		kproc_shutdown_wait, p->p_comm);
720 	} else {
721 	    printf("Waiting (max %d seconds) for system thread %s to stop...",
722 		kproc_shutdown_wait, td->td_comm);
723 	}
724 	error = suspend_kproc(td, kproc_shutdown_wait * hz);
725 
726 	if (error == EWOULDBLOCK)
727 		printf("timed out\n");
728 	else
729 		printf("stopped\n");
730 }
731