xref: /dflybsd-src/sys/kern/kern_shutdown.c (revision aee9908a9a4cf56895f83b219eec6a91b8372915)
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 1.41 2006/11/07 17:51:23 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/vkernel.h>
64 #include <sys/conf.h>
65 #include <sys/sysproto.h>
66 #include <sys/device.h>
67 #include <sys/cons.h>
68 #include <sys/shm.h>
69 #include <sys/kern_syscall.h>
70 #include <vm/vm_map.h>
71 #include <vm/pmap.h>
72 
73 #include <sys/thread2.h>
74 #include <sys/buf2.h>
75 
76 #include <machine/pcb.h>
77 #include <machine/clock.h>
78 #include <machine/md_var.h>
79 #include <machine/smp.h>		/* smp_active_mask, cpuid */
80 
81 #include <sys/signalvar.h>
82 
83 #ifndef PANIC_REBOOT_WAIT_TIME
84 #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
85 #endif
86 
87 /*
88  * Note that stdarg.h and the ANSI style va_start macro is used for both
89  * ANSI and traditional C compilers.  We use the machine version to stay
90  * within the confines of the kernel header files.
91  */
92 #include <machine/stdarg.h>
93 
94 #ifdef DDB
95 #ifdef DDB_UNATTENDED
96 int debugger_on_panic = 0;
97 #else
98 int debugger_on_panic = 1;
99 #endif
100 SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic, CTLFLAG_RW,
101 	&debugger_on_panic, 0, "Run debugger on kernel panic");
102 
103 extern void db_print_backtrace(void);
104 
105 #ifdef DDB_TRACE
106 int trace_on_panic = 1;
107 #else
108 int trace_on_panic = 0;
109 #endif
110 SYSCTL_INT(_debug, OID_AUTO, trace_on_panic, CTLFLAG_RW,
111 	&trace_on_panic, 0, "Print stack trace on kernel panic");
112 #endif
113 
114 static int sync_on_panic = 1;
115 SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RW,
116 	&sync_on_panic, 0, "Do a sync before rebooting from a panic");
117 
118 SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0, "Shutdown environment");
119 
120 #ifdef	HW_WDOG
121 /*
122  * If there is a hardware watchdog, point this at the function needed to
123  * hold it off.
124  * It's needed when the kernel needs to do some lengthy operations.
125  * e.g. in wd.c when dumping core.. It's most annoying to have
126  * your precious core-dump only half written because the wdog kicked in.
127  */
128 watchdog_tickle_fn wdog_tickler = NULL;
129 #endif	/* HW_WDOG */
130 
131 /*
132  * Variable panicstr contains argument to first call to panic; used as flag
133  * to indicate that the kernel has already called panic.
134  */
135 const char *panicstr;
136 
137 int dumping;				/* system is dumping */
138 #ifdef SMP
139 u_int panic_cpu_interlock;		/* panic interlock */
140 globaldata_t panic_cpu_gd;		/* which cpu took the panic */
141 #endif
142 
143 static void boot (int) __dead2;
144 static void dumpsys (void);
145 static int setdumpdev (cdev_t dev);
146 static void poweroff_wait (void *, int);
147 static void print_uptime (void);
148 static void shutdown_halt (void *junk, int howto);
149 static void shutdown_panic (void *junk, int howto);
150 static void shutdown_reset (void *junk, int howto);
151 static int shutdown_busycount1(struct buf *bp, void *info);
152 static int shutdown_busycount2(struct buf *bp, void *info);
153 static void shutdown_cleanup_proc(struct proc *p);
154 
155 /* register various local shutdown events */
156 static void
157 shutdown_conf(void *unused)
158 {
159 	EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL, SHUTDOWN_PRI_FIRST);
160 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL, SHUTDOWN_PRI_LAST + 100);
161 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL, SHUTDOWN_PRI_LAST + 100);
162 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL, SHUTDOWN_PRI_LAST + 200);
163 }
164 
165 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL)
166 
167 /* ARGSUSED */
168 
169 /*
170  * The system call that results in a reboot
171  */
172 int
173 sys_reboot(struct reboot_args *uap)
174 {
175 	struct thread *td = curthread;
176 	int error;
177 
178 	if ((error = suser(td)))
179 		return (error);
180 
181 	boot(uap->opt);
182 	return (0);
183 }
184 
185 /*
186  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
187  */
188 static int shutdown_howto = 0;
189 
190 void
191 shutdown_nice(int howto)
192 {
193 	shutdown_howto = howto;
194 
195 	/* Send a signal to init(8) and have it shutdown the world */
196 	if (initproc != NULL) {
197 		ksignal(initproc, SIGINT);
198 	} else {
199 		/* No init(8) running, so simply reboot */
200 		boot(RB_NOSYNC);
201 	}
202 	return;
203 }
204 static int	waittime = -1;
205 static struct thread *dumpthread;
206 static struct pcb dumppcb;
207 
208 static void
209 print_uptime()
210 {
211 	int f;
212 	struct timespec ts;
213 
214 	getnanouptime(&ts);
215 	printf("Uptime: ");
216 	f = 0;
217 	if (ts.tv_sec >= 86400) {
218 		printf("%ldd", ts.tv_sec / 86400);
219 		ts.tv_sec %= 86400;
220 		f = 1;
221 	}
222 	if (f || ts.tv_sec >= 3600) {
223 		printf("%ldh", ts.tv_sec / 3600);
224 		ts.tv_sec %= 3600;
225 		f = 1;
226 	}
227 	if (f || ts.tv_sec >= 60) {
228 		printf("%ldm", ts.tv_sec / 60);
229 		ts.tv_sec %= 60;
230 		f = 1;
231 	}
232 	printf("%lds\n", ts.tv_sec);
233 }
234 
235 /*
236  *  Go through the rigmarole of shutting down..
237  * this used to be in machdep.c but I'll be dammned if I could see
238  * anything machine dependant in it.
239  */
240 static void
241 boot(int howto)
242 {
243 	/*
244 	 * Get rid of any user scheduler baggage and then give
245 	 * us a high priority.
246 	 */
247 	if (curthread->td_release)
248 		curthread->td_release(curthread);
249 	lwkt_setpri_self(TDPRI_MAX);
250 
251 	/* collect extra flags that shutdown_nice might have set */
252 	howto |= shutdown_howto;
253 
254 #ifdef SMP
255 	/*
256 	 * We really want to shutdown on the BSP.  Subsystems such as ACPI
257 	 * can't power-down the box otherwise.
258 	 */
259 	if (smp_active_mask > 1) {
260 		printf("boot() called on cpu#%d\n", mycpu->gd_cpuid);
261 	}
262 	if (panicstr == NULL && mycpu->gd_cpuid != 0) {
263 		printf("Switching to cpu #0 for shutdown\n");
264 		lwkt_setcpu_self(globaldata_find(0));
265 	}
266 #endif
267 	/*
268 	 * Do any callouts that should be done BEFORE syncing the filesystems.
269 	 */
270 	EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
271 
272 	/*
273 	 * Try to get rid of any remaining FS references.  The calling
274 	 * process, proc0, and init may still hold references.  The
275 	 * VFS cache subsystem may still hold a root reference to root.
276 	 */
277 	if (panicstr == NULL) {
278 		shutdown_cleanup_proc(curproc);
279 		shutdown_cleanup_proc(&proc0);
280 		if (initproc)
281 			shutdown_cleanup_proc(initproc);
282 		vfs_cache_setroot(NULL, NULL);
283 	}
284 
285 	/*
286 	 * Now sync filesystems
287 	 */
288 	if (!cold && (howto & RB_NOSYNC) == 0 && waittime < 0) {
289 		int iter, nbusy, pbusy;
290 
291 		waittime = 0;
292 		printf("\nsyncing disks... ");
293 
294 		sys_sync(NULL);	/* YYY was sync(&proc0, NULL). why proc0 ? */
295 
296 		/*
297 		 * With soft updates, some buffers that are
298 		 * written will be remarked as dirty until other
299 		 * buffers are written.
300 		 */
301 		for (iter = pbusy = 0; iter < 20; iter++) {
302 			nbusy = scan_all_buffers(shutdown_busycount1, NULL);
303 			if (nbusy == 0)
304 				break;
305 			printf("%d ", nbusy);
306 			if (nbusy < pbusy)
307 				iter = 0;
308 			pbusy = nbusy;
309 			/*
310 			 * XXX:
311 			 * Process soft update work queue if buffers don't sync
312 			 * after 6 iterations by permitting the syncer to run.
313 			 */
314 			if (iter > 5 && bioops.io_sync)
315 				(*bioops.io_sync)(NULL);
316 			sys_sync(NULL); /* YYY was sync(&proc0, NULL). why proc0 ? */
317 			tsleep(boot, 0, "shutdn", hz * iter / 20 + 1);
318 		}
319 		printf("\n");
320 		/*
321 		 * Count only busy local buffers to prevent forcing
322 		 * a fsck if we're just a client of a wedged NFS server
323 		 */
324 		nbusy = scan_all_buffers(shutdown_busycount2, NULL);
325 		if (nbusy) {
326 			/*
327 			 * Failed to sync all blocks. Indicate this and don't
328 			 * unmount filesystems (thus forcing an fsck on reboot).
329 			 */
330 			printf("giving up on %d buffers\n", nbusy);
331 #ifdef DDB
332 			Debugger("busy buffer problem");
333 #endif /* DDB */
334 			tsleep(boot, 0, "shutdn", hz * 5 + 1);
335 		} else {
336 			printf("done\n");
337 			/*
338 			 * Unmount filesystems
339 			 */
340 			if (panicstr == NULL)
341 				vfs_unmountall();
342 		}
343 		tsleep(boot, 0, "shutdn", hz / 10 + 1);
344 	}
345 
346 	print_uptime();
347 
348 	/*
349 	 * Ok, now do things that assume all filesystem activity has
350 	 * been completed.
351 	 */
352 	EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
353 	crit_enter();
354 	if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold)
355 		dumpsys();
356 
357 	/* Now that we're going to really halt the system... */
358 	EVENTHANDLER_INVOKE(shutdown_final, howto);
359 
360 	for(;;) ;	/* safety against shutdown_reset not working */
361 	/* NOTREACHED */
362 }
363 
364 static int
365 shutdown_busycount1(struct buf *bp, void *info)
366 {
367 	if ((bp->b_flags & B_INVAL) == 0 && BUF_REFCNT(bp) > 0)
368 		return(1);
369 	if ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)
370 		return (1);
371 	return (0);
372 }
373 
374 static int
375 shutdown_busycount2(struct buf *bp, void *info)
376 {
377 	if (((bp->b_flags & B_INVAL) == 0 && BUF_REFCNT(bp)) ||
378 	    ((bp->b_flags & (B_DELWRI|B_INVAL)) == B_DELWRI)) {
379 		/*
380 		 * Only count buffers undergoing write I/O
381 		 * on the related vnode.
382 		 */
383 		if (bp->b_vp == NULL ||
384 		    bp->b_vp->v_track_write.bk_active == 0) {
385 			return (0);
386 		}
387 #if defined(SHOW_BUSYBUFS) || defined(DIAGNOSTIC)
388 		printf(
389 	    "%p dev:?, flags:%08x, loffset:%lld, doffset:%lld\n",
390 		    bp,
391 		    bp->b_flags, bp->b_loffset,
392 		    bp->b_bio2.bio_offset);
393 #endif
394 		return(1);
395 	}
396 	return(0);
397 }
398 
399 /*
400  * If the shutdown was a clean halt, behave accordingly.
401  */
402 static void
403 shutdown_halt(void *junk, int howto)
404 {
405 	if (howto & RB_HALT) {
406 		printf("\n");
407 		printf("The operating system has halted.\n");
408 		printf("Please press any key to reboot.\n\n");
409 		switch (cngetc()) {
410 		case -1:		/* No console, just die */
411 			cpu_halt();
412 			/* NOTREACHED */
413 		default:
414 			howto &= ~RB_HALT;
415 			break;
416 		}
417 	}
418 }
419 
420 /*
421  * Check to see if the system paniced, pause and then reboot
422  * according to the specified delay.
423  */
424 static void
425 shutdown_panic(void *junk, int howto)
426 {
427 	int loop;
428 
429 	if (howto & RB_DUMP) {
430 		if (PANIC_REBOOT_WAIT_TIME != 0) {
431 			if (PANIC_REBOOT_WAIT_TIME != -1) {
432 				printf("Automatic reboot in %d seconds - "
433 				       "press a key on the console to abort\n",
434 					PANIC_REBOOT_WAIT_TIME);
435 				for (loop = PANIC_REBOOT_WAIT_TIME * 10;
436 				     loop > 0; --loop) {
437 					DELAY(1000 * 100); /* 1/10th second */
438 					/* Did user type a key? */
439 					if (cncheckc() != -1)
440 						break;
441 				}
442 				if (!loop)
443 					return;
444 			}
445 		} else { /* zero time specified - reboot NOW */
446 			return;
447 		}
448 		printf("--> Press a key on the console to reboot,\n");
449 		printf("--> or switch off the system now.\n");
450 		cngetc();
451 	}
452 }
453 
454 /*
455  * Everything done, now reset
456  */
457 static void
458 shutdown_reset(void *junk, int howto)
459 {
460 	printf("Rebooting...\n");
461 	DELAY(1000000);	/* wait 1 sec for printf's to complete and be read */
462 	/* cpu_boot(howto); */ /* doesn't do anything at the moment */
463 	cpu_reset();
464 	/* NOTREACHED */ /* assuming reset worked */
465 }
466 
467 /*
468  * Try to remove FS references in the specified process.  This function
469  * is used during shutdown
470  */
471 static
472 void
473 shutdown_cleanup_proc(struct proc *p)
474 {
475 	struct filedesc *fdp;
476 	struct vmspace *vm;
477 
478 	if (p == NULL)
479 		return;
480 	if ((fdp = p->p_fd) != NULL) {
481 		kern_closefrom(0);
482 		if (fdp->fd_cdir) {
483 			cache_drop(&fdp->fd_ncdir);
484 			vrele(fdp->fd_cdir);
485 			fdp->fd_cdir = NULL;
486 		}
487 		if (fdp->fd_rdir) {
488 			cache_drop(&fdp->fd_nrdir);
489 			vrele(fdp->fd_rdir);
490 			fdp->fd_rdir = NULL;
491 		}
492 		if (fdp->fd_jdir) {
493 			cache_drop(&fdp->fd_njdir);
494 			vrele(fdp->fd_jdir);
495 			fdp->fd_jdir = NULL;
496 		}
497 	}
498 	if (p->p_vkernel)
499 		vkernel_exit(p);
500 	if (p->p_textvp) {
501 		vrele(p->p_textvp);
502 		p->p_textvp = NULL;
503 	}
504 	vm = p->p_vmspace;
505 	if (vm != NULL) {
506 		pmap_remove_pages(vmspace_pmap(vm),
507 				  VM_MIN_USER_ADDRESS,
508 				  VM_MAX_USER_ADDRESS);
509 		vm_map_remove(&vm->vm_map,
510 			      VM_MIN_USER_ADDRESS,
511 			      VM_MAX_USER_ADDRESS);
512 	}
513 }
514 
515 /*
516  * Magic number for savecore
517  *
518  * exported (symorder) and used at least by savecore(8)
519  *
520  */
521 static u_long const	dumpmag = 0x8fca0101UL;
522 
523 static int	dumpsize = 0;		/* also for savecore */
524 
525 static int	dodump = 1;
526 
527 SYSCTL_INT(_machdep, OID_AUTO, do_dump, CTLFLAG_RW, &dodump, 0,
528     "Try to perform coredump on kernel panic");
529 
530 static int
531 setdumpdev(dev)
532 	cdev_t dev;
533 {
534 	int psize;
535 	long newdumplo;
536 
537 	if (dev == NOCDEV) {
538 		dumpdev = dev;
539 		return (0);
540 	}
541 	psize = dev_dpsize(dev);
542 	if (psize == -1)
543 		return (ENXIO);
544 	/*
545 	 * XXX should clean up checking in dumpsys() to be more like this.
546 	 */
547 	newdumplo = psize - Maxmem * (PAGE_SIZE / DEV_BSIZE);
548 	if (newdumplo <= LABELSECTOR)
549 		return (ENOSPC);
550 	dumpdev = dev;
551 	dumplo = newdumplo;
552 	return (0);
553 }
554 
555 
556 /* ARGSUSED */
557 static void dump_conf (void *dummy);
558 static void
559 dump_conf(dummy)
560 	void *dummy;
561 {
562 	char *path;
563 	cdev_t dev;
564 
565 	path = kmalloc(MNAMELEN, M_TEMP, M_WAITOK);
566 	if (TUNABLE_STR_FETCH("dumpdev", path, MNAMELEN) != 0) {
567 		dev = kgetdiskbyname(path);
568 		if (dev != NOCDEV)
569 			dumpdev = dev;
570 	}
571 	kfree(path, M_TEMP);
572 	if (setdumpdev(dumpdev) != 0)
573 		dumpdev = NOCDEV;
574 }
575 
576 SYSINIT(dump_conf, SI_SUB_DUMP_CONF, SI_ORDER_FIRST, dump_conf, NULL)
577 
578 static int
579 sysctl_kern_dumpdev(SYSCTL_HANDLER_ARGS)
580 {
581 	int error;
582 	udev_t ndumpdev;
583 
584 	ndumpdev = dev2udev(dumpdev);
585 	error = sysctl_handle_opaque(oidp, &ndumpdev, sizeof ndumpdev, req);
586 	if (error == 0 && req->newptr != NULL)
587 		error = setdumpdev(udev2dev(ndumpdev, 0));
588 	return (error);
589 }
590 
591 SYSCTL_PROC(_kern, KERN_DUMPDEV, dumpdev, CTLTYPE_OPAQUE|CTLFLAG_RW,
592 	0, sizeof dumpdev, sysctl_kern_dumpdev, "T,udev_t", "");
593 
594 /*
595  * Doadump comes here after turning off memory management and
596  * getting on the dump stack, either when called above, or by
597  * the auto-restart code.
598  */
599 static void
600 dumpsys(void)
601 {
602 	int	error;
603 
604 	savectx(&dumppcb);
605 	dumpthread = curthread;
606 	if (dumping++) {
607 		printf("Dump already in progress, bailing...\n");
608 		return;
609 	}
610 	if (!dodump)
611 		return;
612 	if (dumpdev == NOCDEV)
613 		return;
614 	dumpsize = Maxmem;
615 	printf("\ndumping to dev %s, offset %ld\n", devtoname(dumpdev), dumplo);
616 	printf("dump ");
617 	error = dev_ddump(dumpdev);
618 	if (error == 0) {
619 		printf("succeeded\n");
620 		return;
621 	}
622 	printf("failed, reason: ");
623 	switch (error) {
624 	case ENOSYS:
625 	case ENODEV:
626 		printf("device doesn't support a dump routine\n");
627 		break;
628 
629 	case ENXIO:
630 		printf("device bad\n");
631 		break;
632 
633 	case EFAULT:
634 		printf("device not ready\n");
635 		break;
636 
637 	case EINVAL:
638 		printf("area improper\n");
639 		break;
640 
641 	case EIO:
642 		printf("i/o error\n");
643 		break;
644 
645 	case EINTR:
646 		printf("aborted from console\n");
647 		break;
648 
649 	default:
650 		printf("unknown, error = %d\n", error);
651 		break;
652 	}
653 }
654 
655 int
656 dumpstatus(vm_offset_t addr, off_t count)
657 {
658 	int c;
659 
660 	if (addr % (1024 * 1024) == 0) {
661 #ifdef HW_WDOG
662 		if (wdog_tickler)
663 			(*wdog_tickler)();
664 #endif
665 		printf("%ld ", (long)(count / (1024 * 1024)));
666 	}
667 
668 	if ((c = cncheckc()) == 0x03)
669 		return -1;
670 	else if (c != -1)
671 		printf("[CTRL-C to abort] ");
672 
673 	return 0;
674 }
675 
676 /*
677  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
678  * and then reboots.  If we are called twice, then we avoid trying to sync
679  * the disks as this often leads to recursive panics.
680  */
681 void
682 panic(const char *fmt, ...)
683 {
684 	int bootopt, newpanic;
685 	__va_list ap;
686 	static char buf[256];
687 
688 #ifdef SMP
689 	/*
690 	 * If a panic occurs on multiple cpus before the first is able to
691 	 * halt the other cpus, only one cpu is allowed to take the panic.
692 	 * Attempt to be verbose about this situation but if the printf()
693 	 * itself panics don't let us overrun the kernel stack.
694 	 *
695 	 * Be very nasty about descheduling our thread at the lowest
696 	 * level possible in an attempt to freeze the thread without
697 	 * inducing further panics.
698 	 *
699 	 * Bumping gd_trap_nesting_level will also bypass assertions in
700 	 * lwkt_switch() and allow us to switch away even if we are a
701 	 * FAST interrupt or IPI.
702 	 */
703 	if (atomic_poll_acquire_int(&panic_cpu_interlock)) {
704 		panic_cpu_gd = mycpu;
705 	} else if (panic_cpu_gd != mycpu) {
706 		crit_enter();
707 		++mycpu->gd_trap_nesting_level;
708 		if (mycpu->gd_trap_nesting_level < 25) {
709 			printf("SECONDARY PANIC ON CPU %d THREAD %p\n",
710 				mycpu->gd_cpuid, curthread);
711 		}
712 		curthread->td_release = NULL;	/* be a grinch */
713 		for (;;) {
714 			lwkt_deschedule_self(curthread);
715 			lwkt_switch();
716 		}
717 		/* NOT REACHED */
718 		/* --mycpu->gd_trap_nesting_level */
719 		/* crit_exit() */
720 	}
721 #endif
722 	bootopt = RB_AUTOBOOT | RB_DUMP;
723 	if (sync_on_panic == 0)
724 		bootopt |= RB_NOSYNC;
725 	newpanic = 0;
726 	if (panicstr)
727 		bootopt |= RB_NOSYNC;
728 	else {
729 		panicstr = fmt;
730 		newpanic = 1;
731 	}
732 
733 	__va_start(ap, fmt);
734 	(void)vsnprintf(buf, sizeof(buf), fmt, ap);
735 	if (panicstr == fmt)
736 		panicstr = buf;
737 	__va_end(ap);
738 	printf("panic: %s\n", buf);
739 #ifdef SMP
740 	/* three separate prints in case of an unmapped page and trap */
741 	printf("mp_lock = %08x; ", mp_lock);
742 	printf("cpuid = %d; ", mycpu->gd_cpuid);
743 	printf("lapic.id = %08x\n", lapic.id);
744 #endif
745 
746 #if defined(DDB)
747 	if (newpanic && trace_on_panic)
748 		db_print_backtrace();
749 	if (debugger_on_panic)
750 		Debugger ("panic");
751 #endif
752 	boot(bootopt);
753 }
754 
755 /*
756  * Support for poweroff delay.
757  */
758 #ifndef POWEROFF_DELAY
759 # define POWEROFF_DELAY 5000
760 #endif
761 static int poweroff_delay = POWEROFF_DELAY;
762 
763 SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
764 	&poweroff_delay, 0, "");
765 
766 static void
767 poweroff_wait(void *junk, int howto)
768 {
769 	if(!(howto & RB_POWEROFF) || poweroff_delay <= 0)
770 		return;
771 	DELAY(poweroff_delay * 1000);
772 }
773 
774 /*
775  * Some system processes (e.g. syncer) need to be stopped at appropriate
776  * points in their main loops prior to a system shutdown, so that they
777  * won't interfere with the shutdown process (e.g. by holding a disk buf
778  * to cause sync to fail).  For each of these system processes, register
779  * shutdown_kproc() as a handler for one of shutdown events.
780  */
781 static int kproc_shutdown_wait = 60;
782 SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
783     &kproc_shutdown_wait, 0, "");
784 
785 void
786 shutdown_kproc(void *arg, int howto)
787 {
788 	struct thread *td;
789 	struct proc *p;
790 	int error;
791 
792 	if (panicstr)
793 		return;
794 
795 	td = (struct thread *)arg;
796 	if ((p = td->td_proc) != NULL) {
797 	    printf("Waiting (max %d seconds) for system process `%s' to stop...",
798 		kproc_shutdown_wait, p->p_comm);
799 	} else {
800 	    printf("Waiting (max %d seconds) for system thread %s to stop...",
801 		kproc_shutdown_wait, td->td_comm);
802 	}
803 	error = suspend_kproc(td, kproc_shutdown_wait * hz);
804 
805 	if (error == EWOULDBLOCK)
806 		printf("timed out\n");
807 	else
808 		printf("stopped\n");
809 }
810