The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_shutdown.c

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    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  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)kern_shutdown.c     8.3 (Berkeley) 1/21/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: stable/9/sys/kern/kern_shutdown.c 260433 2014-01-08 02:31:35Z cperciva $");
   39 
   40 #include "opt_ddb.h"
   41 #include "opt_kdb.h"
   42 #include "opt_panic.h"
   43 #include "opt_sched.h"
   44 #include "opt_watchdog.h"
   45 
   46 #include <sys/param.h>
   47 #include <sys/systm.h>
   48 #include <sys/bio.h>
   49 #include <sys/buf.h>
   50 #include <sys/conf.h>
   51 #include <sys/cons.h>
   52 #include <sys/eventhandler.h>
   53 #include <sys/jail.h>
   54 #include <sys/kdb.h>
   55 #include <sys/kernel.h>
   56 #include <sys/kerneldump.h>
   57 #include <sys/kthread.h>
   58 #include <sys/malloc.h>
   59 #include <sys/mount.h>
   60 #include <sys/priv.h>
   61 #include <sys/proc.h>
   62 #include <sys/reboot.h>
   63 #include <sys/resourcevar.h>
   64 #include <sys/sched.h>
   65 #include <sys/smp.h>
   66 #include <sys/sysctl.h>
   67 #include <sys/sysproto.h>
   68 #include <sys/vnode.h>
   69 #include <sys/watchdog.h>
   70 
   71 #include <ddb/ddb.h>
   72 
   73 #include <machine/cpu.h>
   74 #include <machine/pcb.h>
   75 #include <machine/smp.h>
   76 
   77 #include <security/mac/mac_framework.h>
   78 
   79 #include <vm/vm.h>
   80 #include <vm/vm_object.h>
   81 #include <vm/vm_page.h>
   82 #include <vm/vm_pager.h>
   83 #include <vm/swap_pager.h>
   84 
   85 #include <sys/signalvar.h>
   86 
   87 #ifndef PANIC_REBOOT_WAIT_TIME
   88 #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
   89 #endif
   90 static int panic_reboot_wait_time = PANIC_REBOOT_WAIT_TIME;
   91 SYSCTL_INT(_kern, OID_AUTO, panic_reboot_wait_time, CTLFLAG_RW | CTLFLAG_TUN,
   92     &panic_reboot_wait_time, 0,
   93     "Seconds to wait before rebooting after a panic");
   94 TUNABLE_INT("kern.panic_reboot_wait_time", &panic_reboot_wait_time);
   95 
   96 /*
   97  * Note that stdarg.h and the ANSI style va_start macro is used for both
   98  * ANSI and traditional C compilers.
   99  */
  100 #include <machine/stdarg.h>
  101 
  102 #ifdef KDB
  103 #ifdef KDB_UNATTENDED
  104 int debugger_on_panic = 0;
  105 #else
  106 int debugger_on_panic = 1;
  107 #endif
  108 SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic,
  109     CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_TUN,
  110     &debugger_on_panic, 0, "Run debugger on kernel panic");
  111 TUNABLE_INT("debug.debugger_on_panic", &debugger_on_panic);
  112 
  113 #ifdef KDB_TRACE
  114 static int trace_on_panic = 1;
  115 #else
  116 static int trace_on_panic = 0;
  117 #endif
  118 SYSCTL_INT(_debug, OID_AUTO, trace_on_panic,
  119     CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_TUN,
  120     &trace_on_panic, 0, "Print stack trace on kernel panic");
  121 TUNABLE_INT("debug.trace_on_panic", &trace_on_panic);
  122 #endif /* KDB */
  123 
  124 static int sync_on_panic = 0;
  125 SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RW | CTLFLAG_TUN,
  126         &sync_on_panic, 0, "Do a sync before rebooting from a panic");
  127 TUNABLE_INT("kern.sync_on_panic", &sync_on_panic);
  128 
  129 static int stop_scheduler_on_panic = 1;
  130 SYSCTL_INT(_kern, OID_AUTO, stop_scheduler_on_panic, CTLFLAG_RW | CTLFLAG_TUN,
  131     &stop_scheduler_on_panic, 0, "stop scheduler upon entering panic");
  132 TUNABLE_INT("kern.stop_scheduler_on_panic", &stop_scheduler_on_panic);
  133 
  134 static SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0,
  135     "Shutdown environment");
  136 
  137 #ifndef DIAGNOSTIC
  138 static int show_busybufs;
  139 #else
  140 static int show_busybufs = 1;
  141 #endif
  142 SYSCTL_INT(_kern_shutdown, OID_AUTO, show_busybufs, CTLFLAG_RW,
  143         &show_busybufs, 0, "");
  144 
  145 /*
  146  * Variable panicstr contains argument to first call to panic; used as flag
  147  * to indicate that the kernel has already called panic.
  148  */
  149 const char *panicstr;
  150 
  151 int dumping;                            /* system is dumping */
  152 int rebooting;                          /* system is rebooting */
  153 static struct dumperinfo dumper;        /* our selected dumper */
  154 
  155 /* Context information for dump-debuggers. */
  156 static struct pcb dumppcb;              /* Registers. */
  157 lwpid_t dumptid;                        /* Thread ID. */
  158 
  159 static void poweroff_wait(void *, int);
  160 static void shutdown_halt(void *junk, int howto);
  161 static void shutdown_panic(void *junk, int howto);
  162 static void shutdown_reset(void *junk, int howto);
  163 
  164 /* register various local shutdown events */
  165 static void
  166 shutdown_conf(void *unused)
  167 {
  168 
  169         EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL,
  170             SHUTDOWN_PRI_FIRST);
  171         EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL,
  172             SHUTDOWN_PRI_LAST + 100);
  173         EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL,
  174             SHUTDOWN_PRI_LAST + 100);
  175         EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL,
  176             SHUTDOWN_PRI_LAST + 200);
  177 }
  178 
  179 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL);
  180 
  181 /*
  182  * The system call that results in a reboot.
  183  */
  184 /* ARGSUSED */
  185 int
  186 sys_reboot(struct thread *td, struct reboot_args *uap)
  187 {
  188         int error;
  189 
  190         error = 0;
  191 #ifdef MAC
  192         error = mac_system_check_reboot(td->td_ucred, uap->opt);
  193 #endif
  194         if (error == 0)
  195                 error = priv_check(td, PRIV_REBOOT);
  196         if (error == 0) {
  197                 mtx_lock(&Giant);
  198                 kern_reboot(uap->opt);
  199                 mtx_unlock(&Giant);
  200         }
  201         return (error);
  202 }
  203 
  204 /*
  205  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
  206  */
  207 static int shutdown_howto = 0;
  208 
  209 void
  210 shutdown_nice(int howto)
  211 {
  212 
  213         shutdown_howto = howto;
  214 
  215         /* Send a signal to init(8) and have it shutdown the world */
  216         if (initproc != NULL) {
  217                 PROC_LOCK(initproc);
  218                 kern_psignal(initproc, SIGINT);
  219                 PROC_UNLOCK(initproc);
  220         } else {
  221                 /* No init(8) running, so simply reboot */
  222                 kern_reboot(RB_NOSYNC);
  223         }
  224         return;
  225 }
  226 static int      waittime = -1;
  227 
  228 static void
  229 print_uptime(void)
  230 {
  231         int f;
  232         struct timespec ts;
  233 
  234         getnanouptime(&ts);
  235         printf("Uptime: ");
  236         f = 0;
  237         if (ts.tv_sec >= 86400) {
  238                 printf("%ldd", (long)ts.tv_sec / 86400);
  239                 ts.tv_sec %= 86400;
  240                 f = 1;
  241         }
  242         if (f || ts.tv_sec >= 3600) {
  243                 printf("%ldh", (long)ts.tv_sec / 3600);
  244                 ts.tv_sec %= 3600;
  245                 f = 1;
  246         }
  247         if (f || ts.tv_sec >= 60) {
  248                 printf("%ldm", (long)ts.tv_sec / 60);
  249                 ts.tv_sec %= 60;
  250                 f = 1;
  251         }
  252         printf("%lds\n", (long)ts.tv_sec);
  253 }
  254 
  255 int
  256 doadump(boolean_t textdump)
  257 {
  258         boolean_t coredump;
  259 
  260         if (dumping)
  261                 return (EBUSY);
  262         if (dumper.dumper == NULL)
  263                 return (ENXIO);
  264 
  265         savectx(&dumppcb);
  266         dumptid = curthread->td_tid;
  267         dumping++;
  268 
  269         coredump = TRUE;
  270 #ifdef DDB
  271         if (textdump && textdump_pending) {
  272                 coredump = FALSE;
  273                 textdump_dumpsys(&dumper);
  274         }
  275 #endif
  276         if (coredump)
  277                 dumpsys(&dumper);
  278 
  279         dumping--;
  280         return (0);
  281 }
  282 
  283 static int
  284 isbufbusy(struct buf *bp)
  285 {
  286         if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 &&
  287             BUF_ISLOCKED(bp)) ||
  288             ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
  289                 return (1);
  290         return (0);
  291 }
  292 
  293 /*
  294  * Shutdown the system cleanly to prepare for reboot, halt, or power off.
  295  */
  296 void
  297 kern_reboot(int howto)
  298 {
  299         static int first_buf_printf = 1;
  300 
  301 #if defined(SMP)
  302         /*
  303          * Bind us to CPU 0 so that all shutdown code runs there.  Some
  304          * systems don't shutdown properly (i.e., ACPI power off) if we
  305          * run on another processor.
  306          */
  307         if (!SCHEDULER_STOPPED()) {
  308                 thread_lock(curthread);
  309                 sched_bind(curthread, 0);
  310                 thread_unlock(curthread);
  311                 KASSERT(PCPU_GET(cpuid) == 0, ("boot: not running on cpu 0"));
  312         }
  313 #endif
  314         /* We're in the process of rebooting. */
  315         rebooting = 1;
  316 
  317         /* collect extra flags that shutdown_nice might have set */
  318         howto |= shutdown_howto;
  319 
  320         /* We are out of the debugger now. */
  321         kdb_active = 0;
  322 
  323         /*
  324          * Do any callouts that should be done BEFORE syncing the filesystems.
  325          */
  326         EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
  327 
  328         /* 
  329          * Now sync filesystems
  330          */
  331         if (!cold && (howto & RB_NOSYNC) == 0 && waittime < 0) {
  332                 register struct buf *bp;
  333                 int iter, nbusy, pbusy;
  334 #ifndef PREEMPTION
  335                 int subiter;
  336 #endif
  337 
  338                 waittime = 0;
  339 
  340                 wdog_kern_pat(WD_LASTVAL);
  341                 sys_sync(curthread, NULL);
  342 
  343                 /*
  344                  * With soft updates, some buffers that are
  345                  * written will be remarked as dirty until other
  346                  * buffers are written.
  347                  */
  348                 for (iter = pbusy = 0; iter < 20; iter++) {
  349                         nbusy = 0;
  350                         for (bp = &buf[nbuf]; --bp >= buf; )
  351                                 if (isbufbusy(bp))
  352                                         nbusy++;
  353                         if (nbusy == 0) {
  354                                 if (first_buf_printf)
  355                                         printf("All buffers synced.");
  356                                 break;
  357                         }
  358                         if (first_buf_printf) {
  359                                 printf("Syncing disks, buffers remaining... ");
  360                                 first_buf_printf = 0;
  361                         }
  362                         printf("%d ", nbusy);
  363                         if (nbusy < pbusy)
  364                                 iter = 0;
  365                         pbusy = nbusy;
  366 
  367                         wdog_kern_pat(WD_LASTVAL);
  368                         sys_sync(curthread, NULL);
  369 
  370 #ifdef PREEMPTION
  371                         /*
  372                          * Drop Giant and spin for a while to allow
  373                          * interrupt threads to run.
  374                          */
  375                         DROP_GIANT();
  376                         DELAY(50000 * iter);
  377                         PICKUP_GIANT();
  378 #else
  379                         /*
  380                          * Drop Giant and context switch several times to
  381                          * allow interrupt threads to run.
  382                          */
  383                         DROP_GIANT();
  384                         for (subiter = 0; subiter < 50 * iter; subiter++) {
  385                                 thread_lock(curthread);
  386                                 mi_switch(SW_VOL, NULL);
  387                                 thread_unlock(curthread);
  388                                 DELAY(1000);
  389                         }
  390                         PICKUP_GIANT();
  391 #endif
  392                 }
  393                 printf("\n");
  394                 /*
  395                  * Count only busy local buffers to prevent forcing 
  396                  * a fsck if we're just a client of a wedged NFS server
  397                  */
  398                 nbusy = 0;
  399                 for (bp = &buf[nbuf]; --bp >= buf; ) {
  400                         if (isbufbusy(bp)) {
  401 #if 0
  402 /* XXX: This is bogus.  We should probably have a BO_REMOTE flag instead */
  403                                 if (bp->b_dev == NULL) {
  404                                         TAILQ_REMOVE(&mountlist,
  405                                             bp->b_vp->v_mount, mnt_list);
  406                                         continue;
  407                                 }
  408 #endif
  409                                 nbusy++;
  410                                 if (show_busybufs > 0) {
  411                                         printf(
  412             "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
  413                                             nbusy, bp, bp->b_vp, bp->b_flags,
  414                                             (intmax_t)bp->b_blkno,
  415                                             (intmax_t)bp->b_lblkno);
  416                                         BUF_LOCKPRINTINFO(bp);
  417                                         if (show_busybufs > 1)
  418                                                 vn_printf(bp->b_vp,
  419                                                     "vnode content: ");
  420                                 }
  421                         }
  422                 }
  423                 if (nbusy) {
  424                         /*
  425                          * Failed to sync all blocks. Indicate this and don't
  426                          * unmount filesystems (thus forcing an fsck on reboot).
  427                          */
  428                         printf("Giving up on %d buffers\n", nbusy);
  429                         DELAY(5000000); /* 5 seconds */
  430                 } else {
  431                         if (!first_buf_printf)
  432                                 printf("Final sync complete\n");
  433                         /*
  434                          * Unmount filesystems
  435                          */
  436                         if (panicstr == 0)
  437                                 vfs_unmountall();
  438                 }
  439                 swapoff_all();
  440                 DELAY(100000);          /* wait for console output to finish */
  441         }
  442 
  443         print_uptime();
  444 
  445         cngrab();
  446 
  447         /*
  448          * Ok, now do things that assume all filesystem activity has
  449          * been completed.
  450          */
  451         EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
  452 
  453         if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) 
  454                 doadump(TRUE);
  455 
  456         /* Now that we're going to really halt the system... */
  457         EVENTHANDLER_INVOKE(shutdown_final, howto);
  458 
  459         for(;;) ;       /* safety against shutdown_reset not working */
  460         /* NOTREACHED */
  461 }
  462 
  463 /*
  464  * If the shutdown was a clean halt, behave accordingly.
  465  */
  466 static void
  467 shutdown_halt(void *junk, int howto)
  468 {
  469 
  470         if (howto & RB_HALT) {
  471                 printf("\n");
  472                 printf("The operating system has halted.\n");
  473                 printf("Please press any key to reboot.\n\n");
  474                 switch (cngetc()) {
  475                 case -1:                /* No console, just die */
  476                         cpu_halt();
  477                         /* NOTREACHED */
  478                 default:
  479                         howto &= ~RB_HALT;
  480                         break;
  481                 }
  482         }
  483 }
  484 
  485 /*
  486  * Check to see if the system paniced, pause and then reboot
  487  * according to the specified delay.
  488  */
  489 static void
  490 shutdown_panic(void *junk, int howto)
  491 {
  492         int loop;
  493 
  494         if (howto & RB_DUMP) {
  495                 if (panic_reboot_wait_time != 0) {
  496                         if (panic_reboot_wait_time != -1) {
  497                                 printf("Automatic reboot in %d seconds - "
  498                                        "press a key on the console to abort\n",
  499                                         panic_reboot_wait_time);
  500                                 for (loop = panic_reboot_wait_time * 10;
  501                                      loop > 0; --loop) {
  502                                         DELAY(1000 * 100); /* 1/10th second */
  503                                         /* Did user type a key? */
  504                                         if (cncheckc() != -1)
  505                                                 break;
  506                                 }
  507                                 if (!loop)
  508                                         return;
  509                         }
  510                 } else { /* zero time specified - reboot NOW */
  511                         return;
  512                 }
  513                 printf("--> Press a key on the console to reboot,\n");
  514                 printf("--> or switch off the system now.\n");
  515                 cngetc();
  516         }
  517 }
  518 
  519 /*
  520  * Everything done, now reset
  521  */
  522 static void
  523 shutdown_reset(void *junk, int howto)
  524 {
  525 
  526         printf("Rebooting...\n");
  527         DELAY(1000000); /* wait 1 sec for printf's to complete and be read */
  528 
  529         /*
  530          * Acquiring smp_ipi_mtx here has a double effect:
  531          * - it disables interrupts avoiding CPU0 preemption
  532          *   by fast handlers (thus deadlocking  against other CPUs)
  533          * - it avoids deadlocks against smp_rendezvous() or, more 
  534          *   generally, threads busy-waiting, with this spinlock held,
  535          *   and waiting for responses by threads on other CPUs
  536          *   (ie. smp_tlb_shootdown()).
  537          *
  538          * For the !SMP case it just needs to handle the former problem.
  539          */
  540 #ifdef SMP
  541         mtx_lock_spin(&smp_ipi_mtx);
  542 #else
  543         spinlock_enter();
  544 #endif
  545 
  546         /* cpu_boot(howto); */ /* doesn't do anything at the moment */
  547         cpu_reset();
  548         /* NOTREACHED */ /* assuming reset worked */
  549 }
  550 
  551 /*
  552  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
  553  * and then reboots.  If we are called twice, then we avoid trying to sync
  554  * the disks as this often leads to recursive panics.
  555  */
  556 void
  557 panic(const char *fmt, ...)
  558 {
  559 #ifdef SMP
  560         static volatile u_int panic_cpu = NOCPU;
  561         cpuset_t other_cpus;
  562 #endif
  563         struct thread *td = curthread;
  564         int bootopt, newpanic;
  565         va_list ap;
  566         static char buf[256];
  567 
  568         if (stop_scheduler_on_panic)
  569                 spinlock_enter();
  570         else
  571                 critical_enter();
  572 
  573 #ifdef SMP
  574         /*
  575          * We don't want multiple CPU's to panic at the same time, so we
  576          * use panic_cpu as a simple spinlock.  We have to keep checking
  577          * panic_cpu if we are spinning in case the panic on the first
  578          * CPU is canceled.
  579          */
  580         if (panic_cpu != PCPU_GET(cpuid))
  581                 while (atomic_cmpset_int(&panic_cpu, NOCPU,
  582                     PCPU_GET(cpuid)) == 0)
  583                         while (panic_cpu != NOCPU)
  584                                 ; /* nothing */
  585 
  586         if (stop_scheduler_on_panic) {
  587                 if (panicstr == NULL && !kdb_active) {
  588                         other_cpus = all_cpus;
  589                         CPU_CLR(PCPU_GET(cpuid), &other_cpus);
  590                         stop_cpus_hard(other_cpus);
  591                 }
  592 
  593                 /*
  594                  * We set stop_scheduler here and not in the block above,
  595                  * because we want to ensure that if panic has been called and
  596                  * stop_scheduler_on_panic is true, then stop_scheduler will
  597                  * always be set.  Even if panic has been entered from kdb.
  598                  */
  599                 td->td_stopsched = 1;
  600         }
  601 #endif
  602 
  603         bootopt = RB_AUTOBOOT;
  604         newpanic = 0;
  605         if (panicstr)
  606                 bootopt |= RB_NOSYNC;
  607         else {
  608                 bootopt |= RB_DUMP;
  609                 panicstr = fmt;
  610                 newpanic = 1;
  611         }
  612 
  613         va_start(ap, fmt);
  614         if (newpanic) {
  615                 (void)vsnprintf(buf, sizeof(buf), fmt, ap);
  616                 panicstr = buf;
  617                 cngrab();
  618                 printf("panic: %s\n", buf);
  619         } else {
  620                 printf("panic: ");
  621                 vprintf(fmt, ap);
  622                 printf("\n");
  623         }
  624         va_end(ap);
  625 #ifdef SMP
  626         printf("cpuid = %d\n", PCPU_GET(cpuid));
  627 #endif
  628 
  629 #ifdef KDB
  630         if (newpanic && trace_on_panic)
  631                 kdb_backtrace();
  632         if (debugger_on_panic)
  633                 kdb_enter(KDB_WHY_PANIC, "panic");
  634 #endif
  635         /*thread_lock(td); */
  636         td->td_flags |= TDF_INPANIC;
  637         /* thread_unlock(td); */
  638         if (!sync_on_panic)
  639                 bootopt |= RB_NOSYNC;
  640         if (!stop_scheduler_on_panic)
  641                 critical_exit();
  642         kern_reboot(bootopt);
  643 }
  644 
  645 /*
  646  * Support for poweroff delay.
  647  *
  648  * Please note that setting this delay too short might power off your machine
  649  * before the write cache on your hard disk has been flushed, leading to
  650  * soft-updates inconsistencies.
  651  */
  652 #ifndef POWEROFF_DELAY
  653 # define POWEROFF_DELAY 5000
  654 #endif
  655 static int poweroff_delay = POWEROFF_DELAY;
  656 
  657 SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
  658         &poweroff_delay, 0, "");
  659 
  660 static void
  661 poweroff_wait(void *junk, int howto)
  662 {
  663 
  664         if (!(howto & RB_POWEROFF) || poweroff_delay <= 0)
  665                 return;
  666         DELAY(poweroff_delay * 1000);
  667 }
  668 
  669 /*
  670  * Some system processes (e.g. syncer) need to be stopped at appropriate
  671  * points in their main loops prior to a system shutdown, so that they
  672  * won't interfere with the shutdown process (e.g. by holding a disk buf
  673  * to cause sync to fail).  For each of these system processes, register
  674  * shutdown_kproc() as a handler for one of shutdown events.
  675  */
  676 static int kproc_shutdown_wait = 60;
  677 SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
  678     &kproc_shutdown_wait, 0, "");
  679 
  680 void
  681 kproc_shutdown(void *arg, int howto)
  682 {
  683         struct proc *p;
  684         int error;
  685 
  686         if (panicstr)
  687                 return;
  688 
  689         p = (struct proc *)arg;
  690         printf("Waiting (max %d seconds) for system process `%s' to stop...",
  691             kproc_shutdown_wait, p->p_comm);
  692         error = kproc_suspend(p, kproc_shutdown_wait * hz);
  693 
  694         if (error == EWOULDBLOCK)
  695                 printf("timed out\n");
  696         else
  697                 printf("done\n");
  698 }
  699 
  700 void
  701 kthread_shutdown(void *arg, int howto)
  702 {
  703         struct thread *td;
  704         int error;
  705 
  706         if (panicstr)
  707                 return;
  708 
  709         td = (struct thread *)arg;
  710         printf("Waiting (max %d seconds) for system thread `%s' to stop...",
  711             kproc_shutdown_wait, td->td_name);
  712         error = kthread_suspend(td, kproc_shutdown_wait * hz);
  713 
  714         if (error == EWOULDBLOCK)
  715                 printf("timed out\n");
  716         else
  717                 printf("done\n");
  718 }
  719 
  720 /* Registration of dumpers */
  721 int
  722 set_dumper(struct dumperinfo *di)
  723 {
  724 
  725         if (di == NULL) {
  726                 bzero(&dumper, sizeof dumper);
  727                 return (0);
  728         }
  729         if (dumper.dumper != NULL)
  730                 return (EBUSY);
  731         dumper = *di;
  732         return (0);
  733 }
  734 
  735 /* Call dumper with bounds checking. */
  736 int
  737 dump_write(struct dumperinfo *di, void *virtual, vm_offset_t physical,
  738     off_t offset, size_t length)
  739 {
  740 
  741         if (length != 0 && (offset < di->mediaoffset ||
  742             offset - di->mediaoffset + length > di->mediasize)) {
  743                 printf("Attempt to write outside dump device boundaries.\n"
  744             "offset(%jd), mediaoffset(%jd), length(%ju), mediasize(%jd).\n",
  745                     (intmax_t)offset, (intmax_t)di->mediaoffset,
  746                     (uintmax_t)length, (intmax_t)di->mediasize);
  747                 return (ENOSPC);
  748         }
  749         return (di->dumper(di->priv, virtual, physical, offset, length));
  750 }
  751 
  752 void
  753 mkdumpheader(struct kerneldumpheader *kdh, char *magic, uint32_t archver,
  754     uint64_t dumplen, uint32_t blksz)
  755 {
  756 
  757         bzero(kdh, sizeof(*kdh));
  758         strncpy(kdh->magic, magic, sizeof(kdh->magic));
  759         strncpy(kdh->architecture, MACHINE_ARCH, sizeof(kdh->architecture));
  760         kdh->version = htod32(KERNELDUMPVERSION);
  761         kdh->architectureversion = htod32(archver);
  762         kdh->dumplength = htod64(dumplen);
  763         kdh->dumptime = htod64(time_second);
  764         kdh->blocksize = htod32(blksz);
  765         strncpy(kdh->hostname, prison0.pr_hostname, sizeof(kdh->hostname));
  766         strncpy(kdh->versionstring, version, sizeof(kdh->versionstring));
  767         if (panicstr != NULL)
  768                 strncpy(kdh->panicstring, panicstr, sizeof(kdh->panicstring));
  769         kdh->parity = kerneldump_parity(kdh);
  770 }

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