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: releng/10.1/sys/kern/kern_shutdown.c 260431 2014-01-08 02:19:39Z 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/ktr.h>
   59 #include <sys/malloc.h>
   60 #include <sys/mount.h>
   61 #include <sys/priv.h>
   62 #include <sys/proc.h>
   63 #include <sys/reboot.h>
   64 #include <sys/resourcevar.h>
   65 #include <sys/rwlock.h>
   66 #include <sys/sched.h>
   67 #include <sys/smp.h>
   68 #include <sys/sysctl.h>
   69 #include <sys/sysproto.h>
   70 #include <sys/vnode.h>
   71 #include <sys/watchdog.h>
   72 
   73 #include <ddb/ddb.h>
   74 
   75 #include <machine/cpu.h>
   76 #include <machine/pcb.h>
   77 #include <machine/smp.h>
   78 
   79 #include <security/mac/mac_framework.h>
   80 
   81 #include <vm/vm.h>
   82 #include <vm/vm_object.h>
   83 #include <vm/vm_page.h>
   84 #include <vm/vm_pager.h>
   85 #include <vm/swap_pager.h>
   86 
   87 #include <sys/signalvar.h>
   88 
   89 #ifndef PANIC_REBOOT_WAIT_TIME
   90 #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
   91 #endif
   92 static int panic_reboot_wait_time = PANIC_REBOOT_WAIT_TIME;
   93 SYSCTL_INT(_kern, OID_AUTO, panic_reboot_wait_time, CTLFLAG_RW | CTLFLAG_TUN,
   94     &panic_reboot_wait_time, 0,
   95     "Seconds to wait before rebooting after a panic");
   96 TUNABLE_INT("kern.panic_reboot_wait_time", &panic_reboot_wait_time);
   97 
   98 /*
   99  * Note that stdarg.h and the ANSI style va_start macro is used for both
  100  * ANSI and traditional C compilers.
  101  */
  102 #include <machine/stdarg.h>
  103 
  104 #ifdef KDB
  105 #ifdef KDB_UNATTENDED
  106 int debugger_on_panic = 0;
  107 #else
  108 int debugger_on_panic = 1;
  109 #endif
  110 SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic,
  111     CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_TUN,
  112     &debugger_on_panic, 0, "Run debugger on kernel panic");
  113 TUNABLE_INT("debug.debugger_on_panic", &debugger_on_panic);
  114 
  115 #ifdef KDB_TRACE
  116 static int trace_on_panic = 1;
  117 #else
  118 static int trace_on_panic = 0;
  119 #endif
  120 SYSCTL_INT(_debug, OID_AUTO, trace_on_panic,
  121     CTLFLAG_RW | CTLFLAG_SECURE | CTLFLAG_TUN,
  122     &trace_on_panic, 0, "Print stack trace on kernel panic");
  123 TUNABLE_INT("debug.trace_on_panic", &trace_on_panic);
  124 #endif /* KDB */
  125 
  126 static int sync_on_panic = 0;
  127 SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RW | CTLFLAG_TUN,
  128         &sync_on_panic, 0, "Do a sync before rebooting from a panic");
  129 TUNABLE_INT("kern.sync_on_panic", &sync_on_panic);
  130 
  131 static SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0,
  132     "Shutdown environment");
  133 
  134 #ifndef DIAGNOSTIC
  135 static int show_busybufs;
  136 #else
  137 static int show_busybufs = 1;
  138 #endif
  139 SYSCTL_INT(_kern_shutdown, OID_AUTO, show_busybufs, CTLFLAG_RW,
  140         &show_busybufs, 0, "");
  141 
  142 /*
  143  * Variable panicstr contains argument to first call to panic; used as flag
  144  * to indicate that the kernel has already called panic.
  145  */
  146 const char *panicstr;
  147 
  148 int dumping;                            /* system is dumping */
  149 int rebooting;                          /* system is rebooting */
  150 static struct dumperinfo dumper;        /* our selected dumper */
  151 
  152 /* Context information for dump-debuggers. */
  153 static struct pcb dumppcb;              /* Registers. */
  154 lwpid_t dumptid;                        /* Thread ID. */
  155 
  156 static void poweroff_wait(void *, int);
  157 static void shutdown_halt(void *junk, int howto);
  158 static void shutdown_panic(void *junk, int howto);
  159 static void shutdown_reset(void *junk, int howto);
  160 static void vpanic(const char *fmt, va_list ap) __dead2;
  161 
  162 /* register various local shutdown events */
  163 static void
  164 shutdown_conf(void *unused)
  165 {
  166 
  167         EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL,
  168             SHUTDOWN_PRI_FIRST);
  169         EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL,
  170             SHUTDOWN_PRI_LAST + 100);
  171         EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL,
  172             SHUTDOWN_PRI_LAST + 100);
  173         EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL,
  174             SHUTDOWN_PRI_LAST + 200);
  175 }
  176 
  177 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL);
  178 
  179 /*
  180  * The system call that results in a reboot.
  181  */
  182 /* ARGSUSED */
  183 int
  184 sys_reboot(struct thread *td, struct reboot_args *uap)
  185 {
  186         int error;
  187 
  188         error = 0;
  189 #ifdef MAC
  190         error = mac_system_check_reboot(td->td_ucred, uap->opt);
  191 #endif
  192         if (error == 0)
  193                 error = priv_check(td, PRIV_REBOOT);
  194         if (error == 0) {
  195                 mtx_lock(&Giant);
  196                 kern_reboot(uap->opt);
  197                 mtx_unlock(&Giant);
  198         }
  199         return (error);
  200 }
  201 
  202 /*
  203  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
  204  */
  205 static int shutdown_howto = 0;
  206 
  207 void
  208 shutdown_nice(int howto)
  209 {
  210 
  211         shutdown_howto = howto;
  212 
  213         /* Send a signal to init(8) and have it shutdown the world */
  214         if (initproc != NULL) {
  215                 PROC_LOCK(initproc);
  216                 kern_psignal(initproc, SIGINT);
  217                 PROC_UNLOCK(initproc);
  218         } else {
  219                 /* No init(8) running, so simply reboot */
  220                 kern_reboot(RB_NOSYNC);
  221         }
  222         return;
  223 }
  224 static int      waittime = -1;
  225 
  226 static void
  227 print_uptime(void)
  228 {
  229         int f;
  230         struct timespec ts;
  231 
  232         getnanouptime(&ts);
  233         printf("Uptime: ");
  234         f = 0;
  235         if (ts.tv_sec >= 86400) {
  236                 printf("%ldd", (long)ts.tv_sec / 86400);
  237                 ts.tv_sec %= 86400;
  238                 f = 1;
  239         }
  240         if (f || ts.tv_sec >= 3600) {
  241                 printf("%ldh", (long)ts.tv_sec / 3600);
  242                 ts.tv_sec %= 3600;
  243                 f = 1;
  244         }
  245         if (f || ts.tv_sec >= 60) {
  246                 printf("%ldm", (long)ts.tv_sec / 60);
  247                 ts.tv_sec %= 60;
  248                 f = 1;
  249         }
  250         printf("%lds\n", (long)ts.tv_sec);
  251 }
  252 
  253 int
  254 doadump(boolean_t textdump)
  255 {
  256         boolean_t coredump;
  257 
  258         if (dumping)
  259                 return (EBUSY);
  260         if (dumper.dumper == NULL)
  261                 return (ENXIO);
  262 
  263         savectx(&dumppcb);
  264         dumptid = curthread->td_tid;
  265         dumping++;
  266 
  267         coredump = TRUE;
  268 #ifdef DDB
  269         if (textdump && textdump_pending) {
  270                 coredump = FALSE;
  271                 textdump_dumpsys(&dumper);
  272         }
  273 #endif
  274         if (coredump)
  275                 dumpsys(&dumper);
  276 
  277         dumping--;
  278         return (0);
  279 }
  280 
  281 static int
  282 isbufbusy(struct buf *bp)
  283 {
  284         if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 &&
  285             BUF_ISLOCKED(bp)) ||
  286             ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
  287                 return (1);
  288         return (0);
  289 }
  290 
  291 /*
  292  * Shutdown the system cleanly to prepare for reboot, halt, or power off.
  293  */
  294 void
  295 kern_reboot(int howto)
  296 {
  297         static int first_buf_printf = 1;
  298 
  299 #if defined(SMP)
  300         /*
  301          * Bind us to CPU 0 so that all shutdown code runs there.  Some
  302          * systems don't shutdown properly (i.e., ACPI power off) if we
  303          * run on another processor.
  304          */
  305         if (!SCHEDULER_STOPPED()) {
  306                 thread_lock(curthread);
  307                 sched_bind(curthread, 0);
  308                 thread_unlock(curthread);
  309                 KASSERT(PCPU_GET(cpuid) == 0, ("boot: not running on cpu 0"));
  310         }
  311 #endif
  312         /* We're in the process of rebooting. */
  313         rebooting = 1;
  314 
  315         /* collect extra flags that shutdown_nice might have set */
  316         howto |= shutdown_howto;
  317 
  318         /* We are out of the debugger now. */
  319         kdb_active = 0;
  320 
  321         /*
  322          * Do any callouts that should be done BEFORE syncing the filesystems.
  323          */
  324         EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
  325 
  326         /* 
  327          * Now sync filesystems
  328          */
  329         if (!cold && (howto & RB_NOSYNC) == 0 && waittime < 0) {
  330                 register struct buf *bp;
  331                 int iter, nbusy, pbusy;
  332 #ifndef PREEMPTION
  333                 int subiter;
  334 #endif
  335 
  336                 waittime = 0;
  337 
  338                 wdog_kern_pat(WD_LASTVAL);
  339                 sys_sync(curthread, NULL);
  340 
  341                 /*
  342                  * With soft updates, some buffers that are
  343                  * written will be remarked as dirty until other
  344                  * buffers are written.
  345                  */
  346                 for (iter = pbusy = 0; iter < 20; iter++) {
  347                         nbusy = 0;
  348                         for (bp = &buf[nbuf]; --bp >= buf; )
  349                                 if (isbufbusy(bp))
  350                                         nbusy++;
  351                         if (nbusy == 0) {
  352                                 if (first_buf_printf)
  353                                         printf("All buffers synced.");
  354                                 break;
  355                         }
  356                         if (first_buf_printf) {
  357                                 printf("Syncing disks, buffers remaining... ");
  358                                 first_buf_printf = 0;
  359                         }
  360                         printf("%d ", nbusy);
  361                         if (nbusy < pbusy)
  362                                 iter = 0;
  363                         pbusy = nbusy;
  364 
  365                         wdog_kern_pat(WD_LASTVAL);
  366                         sys_sync(curthread, NULL);
  367 
  368 #ifdef PREEMPTION
  369                         /*
  370                          * Drop Giant and spin for a while to allow
  371                          * interrupt threads to run.
  372                          */
  373                         DROP_GIANT();
  374                         DELAY(50000 * iter);
  375                         PICKUP_GIANT();
  376 #else
  377                         /*
  378                          * Drop Giant and context switch several times to
  379                          * allow interrupt threads to run.
  380                          */
  381                         DROP_GIANT();
  382                         for (subiter = 0; subiter < 50 * iter; subiter++) {
  383                                 thread_lock(curthread);
  384                                 mi_switch(SW_VOL, NULL);
  385                                 thread_unlock(curthread);
  386                                 DELAY(1000);
  387                         }
  388                         PICKUP_GIANT();
  389 #endif
  390                 }
  391                 printf("\n");
  392                 /*
  393                  * Count only busy local buffers to prevent forcing 
  394                  * a fsck if we're just a client of a wedged NFS server
  395                  */
  396                 nbusy = 0;
  397                 for (bp = &buf[nbuf]; --bp >= buf; ) {
  398                         if (isbufbusy(bp)) {
  399 #if 0
  400 /* XXX: This is bogus.  We should probably have a BO_REMOTE flag instead */
  401                                 if (bp->b_dev == NULL) {
  402                                         TAILQ_REMOVE(&mountlist,
  403                                             bp->b_vp->v_mount, mnt_list);
  404                                         continue;
  405                                 }
  406 #endif
  407                                 nbusy++;
  408                                 if (show_busybufs > 0) {
  409                                         printf(
  410             "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
  411                                             nbusy, bp, bp->b_vp, bp->b_flags,
  412                                             (intmax_t)bp->b_blkno,
  413                                             (intmax_t)bp->b_lblkno);
  414                                         BUF_LOCKPRINTINFO(bp);
  415                                         if (show_busybufs > 1)
  416                                                 vn_printf(bp->b_vp,
  417                                                     "vnode content: ");
  418                                 }
  419                         }
  420                 }
  421                 if (nbusy) {
  422                         /*
  423                          * Failed to sync all blocks. Indicate this and don't
  424                          * unmount filesystems (thus forcing an fsck on reboot).
  425                          */
  426                         printf("Giving up on %d buffers\n", nbusy);
  427                         DELAY(5000000); /* 5 seconds */
  428                 } else {
  429                         if (!first_buf_printf)
  430                                 printf("Final sync complete\n");
  431                         /*
  432                          * Unmount filesystems
  433                          */
  434                         if (panicstr == 0)
  435                                 vfs_unmountall();
  436                 }
  437                 swapoff_all();
  438                 DELAY(100000);          /* wait for console output to finish */
  439         }
  440 
  441         print_uptime();
  442 
  443         cngrab();
  444 
  445         /*
  446          * Ok, now do things that assume all filesystem activity has
  447          * been completed.
  448          */
  449         EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
  450 
  451         if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) 
  452                 doadump(TRUE);
  453 
  454         /* Now that we're going to really halt the system... */
  455         EVENTHANDLER_INVOKE(shutdown_final, howto);
  456 
  457         for(;;) ;       /* safety against shutdown_reset not working */
  458         /* NOTREACHED */
  459 }
  460 
  461 /*
  462  * If the shutdown was a clean halt, behave accordingly.
  463  */
  464 static void
  465 shutdown_halt(void *junk, int howto)
  466 {
  467 
  468         if (howto & RB_HALT) {
  469                 printf("\n");
  470                 printf("The operating system has halted.\n");
  471                 printf("Please press any key to reboot.\n\n");
  472                 switch (cngetc()) {
  473                 case -1:                /* No console, just die */
  474                         cpu_halt();
  475                         /* NOTREACHED */
  476                 default:
  477                         howto &= ~RB_HALT;
  478                         break;
  479                 }
  480         }
  481 }
  482 
  483 /*
  484  * Check to see if the system paniced, pause and then reboot
  485  * according to the specified delay.
  486  */
  487 static void
  488 shutdown_panic(void *junk, int howto)
  489 {
  490         int loop;
  491 
  492         if (howto & RB_DUMP) {
  493                 if (panic_reboot_wait_time != 0) {
  494                         if (panic_reboot_wait_time != -1) {
  495                                 printf("Automatic reboot in %d seconds - "
  496                                        "press a key on the console to abort\n",
  497                                         panic_reboot_wait_time);
  498                                 for (loop = panic_reboot_wait_time * 10;
  499                                      loop > 0; --loop) {
  500                                         DELAY(1000 * 100); /* 1/10th second */
  501                                         /* Did user type a key? */
  502                                         if (cncheckc() != -1)
  503                                                 break;
  504                                 }
  505                                 if (!loop)
  506                                         return;
  507                         }
  508                 } else { /* zero time specified - reboot NOW */
  509                         return;
  510                 }
  511                 printf("--> Press a key on the console to reboot,\n");
  512                 printf("--> or switch off the system now.\n");
  513                 cngetc();
  514         }
  515 }
  516 
  517 /*
  518  * Everything done, now reset
  519  */
  520 static void
  521 shutdown_reset(void *junk, int howto)
  522 {
  523 
  524         printf("Rebooting...\n");
  525         DELAY(1000000); /* wait 1 sec for printf's to complete and be read */
  526 
  527         /*
  528          * Acquiring smp_ipi_mtx here has a double effect:
  529          * - it disables interrupts avoiding CPU0 preemption
  530          *   by fast handlers (thus deadlocking  against other CPUs)
  531          * - it avoids deadlocks against smp_rendezvous() or, more 
  532          *   generally, threads busy-waiting, with this spinlock held,
  533          *   and waiting for responses by threads on other CPUs
  534          *   (ie. smp_tlb_shootdown()).
  535          *
  536          * For the !SMP case it just needs to handle the former problem.
  537          */
  538 #ifdef SMP
  539         mtx_lock_spin(&smp_ipi_mtx);
  540 #else
  541         spinlock_enter();
  542 #endif
  543 
  544         /* cpu_boot(howto); */ /* doesn't do anything at the moment */
  545         cpu_reset();
  546         /* NOTREACHED */ /* assuming reset worked */
  547 }
  548 
  549 #if defined(WITNESS) || defined(INVARIANTS)
  550 static int kassert_warn_only = 0;
  551 #ifdef KDB
  552 static int kassert_do_kdb = 0;
  553 #endif
  554 #ifdef KTR
  555 static int kassert_do_ktr = 0;
  556 #endif
  557 static int kassert_do_log = 1;
  558 static int kassert_log_pps_limit = 4;
  559 static int kassert_log_mute_at = 0;
  560 static int kassert_log_panic_at = 0;
  561 static int kassert_warnings = 0;
  562 
  563 SYSCTL_NODE(_debug, OID_AUTO, kassert, CTLFLAG_RW, NULL, "kassert options");
  564 
  565 SYSCTL_INT(_debug_kassert, OID_AUTO, warn_only, CTLFLAG_RW | CTLFLAG_TUN,
  566     &kassert_warn_only, 0,
  567     "KASSERT triggers a panic (1) or just a warning (0)");
  568 TUNABLE_INT("debug.kassert.warn_only", &kassert_warn_only);
  569 
  570 #ifdef KDB
  571 SYSCTL_INT(_debug_kassert, OID_AUTO, do_kdb, CTLFLAG_RW | CTLFLAG_TUN,
  572     &kassert_do_kdb, 0, "KASSERT will enter the debugger");
  573 TUNABLE_INT("debug.kassert.do_kdb", &kassert_do_kdb);
  574 #endif
  575 
  576 #ifdef KTR
  577 SYSCTL_UINT(_debug_kassert, OID_AUTO, do_ktr, CTLFLAG_RW | CTLFLAG_TUN,
  578     &kassert_do_ktr, 0,
  579     "KASSERT does a KTR, set this to the KTRMASK you want");
  580 TUNABLE_INT("debug.kassert.do_ktr", &kassert_do_ktr);
  581 #endif
  582 
  583 SYSCTL_INT(_debug_kassert, OID_AUTO, do_log, CTLFLAG_RW | CTLFLAG_TUN,
  584     &kassert_do_log, 0, "KASSERT triggers a panic (1) or just a warning (0)");
  585 TUNABLE_INT("debug.kassert.do_log", &kassert_do_log);
  586 
  587 SYSCTL_INT(_debug_kassert, OID_AUTO, warnings, CTLFLAG_RW | CTLFLAG_TUN,
  588     &kassert_warnings, 0, "number of KASSERTs that have been triggered");
  589 TUNABLE_INT("debug.kassert.warnings", &kassert_warnings);
  590 
  591 SYSCTL_INT(_debug_kassert, OID_AUTO, log_panic_at, CTLFLAG_RW | CTLFLAG_TUN,
  592     &kassert_log_panic_at, 0, "max number of KASSERTS before we will panic");
  593 TUNABLE_INT("debug.kassert.log_panic_at", &kassert_log_panic_at);
  594 
  595 SYSCTL_INT(_debug_kassert, OID_AUTO, log_pps_limit, CTLFLAG_RW | CTLFLAG_TUN,
  596     &kassert_log_pps_limit, 0, "limit number of log messages per second");
  597 TUNABLE_INT("debug.kassert.log_pps_limit", &kassert_log_pps_limit);
  598 
  599 SYSCTL_INT(_debug_kassert, OID_AUTO, log_mute_at, CTLFLAG_RW | CTLFLAG_TUN,
  600     &kassert_log_mute_at, 0, "max number of KASSERTS to log");
  601 TUNABLE_INT("debug.kassert.log_mute_at", &kassert_log_mute_at);
  602 
  603 static int kassert_sysctl_kassert(SYSCTL_HANDLER_ARGS);
  604 
  605 SYSCTL_PROC(_debug_kassert, OID_AUTO, kassert,
  606     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
  607     kassert_sysctl_kassert, "I", "set to trigger a test kassert");
  608 
  609 static int
  610 kassert_sysctl_kassert(SYSCTL_HANDLER_ARGS)
  611 {
  612         int error, i;
  613 
  614         error = sysctl_wire_old_buffer(req, sizeof(int));
  615         if (error == 0) {
  616                 i = 0;
  617                 error = sysctl_handle_int(oidp, &i, 0, req);
  618         }
  619         if (error != 0 || req->newptr == NULL)
  620                 return (error);
  621         KASSERT(0, ("kassert_sysctl_kassert triggered kassert %d", i));
  622         return (0);
  623 }
  624 
  625 /*
  626  * Called by KASSERT, this decides if we will panic
  627  * or if we will log via printf and/or ktr.
  628  */
  629 void
  630 kassert_panic(const char *fmt, ...)
  631 {
  632         static char buf[256];
  633         va_list ap;
  634 
  635         va_start(ap, fmt);
  636         (void)vsnprintf(buf, sizeof(buf), fmt, ap);
  637         va_end(ap);
  638 
  639         /*
  640          * panic if we're not just warning, or if we've exceeded
  641          * kassert_log_panic_at warnings.
  642          */
  643         if (!kassert_warn_only ||
  644             (kassert_log_panic_at > 0 &&
  645              kassert_warnings >= kassert_log_panic_at)) {
  646                 va_start(ap, fmt);
  647                 vpanic(fmt, ap);
  648                 /* NORETURN */
  649         }
  650 #ifdef KTR
  651         if (kassert_do_ktr)
  652                 CTR0(ktr_mask, buf);
  653 #endif /* KTR */
  654         /*
  655          * log if we've not yet met the mute limit.
  656          */
  657         if (kassert_do_log &&
  658             (kassert_log_mute_at == 0 ||
  659              kassert_warnings < kassert_log_mute_at)) {
  660                 static  struct timeval lasterr;
  661                 static  int curerr;
  662 
  663                 if (ppsratecheck(&lasterr, &curerr, kassert_log_pps_limit)) {
  664                         printf("KASSERT failed: %s\n", buf);
  665                         kdb_backtrace();
  666                 }
  667         }
  668 #ifdef KDB
  669         if (kassert_do_kdb) {
  670                 kdb_enter(KDB_WHY_KASSERT, buf);
  671         }
  672 #endif
  673         atomic_add_int(&kassert_warnings, 1);
  674 }
  675 #endif
  676 
  677 /*
  678  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
  679  * and then reboots.  If we are called twice, then we avoid trying to sync
  680  * the disks as this often leads to recursive panics.
  681  */
  682 void
  683 panic(const char *fmt, ...)
  684 {
  685         va_list ap;
  686 
  687         va_start(ap, fmt);
  688         vpanic(fmt, ap);
  689 }
  690 
  691 static void
  692 vpanic(const char *fmt, va_list ap)
  693 {
  694 #ifdef SMP
  695         cpuset_t other_cpus;
  696 #endif
  697         struct thread *td = curthread;
  698         int bootopt, newpanic;
  699         static char buf[256];
  700 
  701         spinlock_enter();
  702 
  703 #ifdef SMP
  704         /*
  705          * stop_cpus_hard(other_cpus) should prevent multiple CPUs from
  706          * concurrently entering panic.  Only the winner will proceed
  707          * further.
  708          */
  709         if (panicstr == NULL && !kdb_active) {
  710                 other_cpus = all_cpus;
  711                 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
  712                 stop_cpus_hard(other_cpus);
  713         }
  714 
  715         /*
  716          * We set stop_scheduler here and not in the block above,
  717          * because we want to ensure that if panic has been called and
  718          * stop_scheduler_on_panic is true, then stop_scheduler will
  719          * always be set.  Even if panic has been entered from kdb.
  720          */
  721         td->td_stopsched = 1;
  722 #endif
  723 
  724         bootopt = RB_AUTOBOOT;
  725         newpanic = 0;
  726         if (panicstr)
  727                 bootopt |= RB_NOSYNC;
  728         else {
  729                 bootopt |= RB_DUMP;
  730                 panicstr = fmt;
  731                 newpanic = 1;
  732         }
  733 
  734         if (newpanic) {
  735                 (void)vsnprintf(buf, sizeof(buf), fmt, ap);
  736                 panicstr = buf;
  737                 cngrab();
  738                 printf("panic: %s\n", buf);
  739         } else {
  740                 printf("panic: ");
  741                 vprintf(fmt, ap);
  742                 printf("\n");
  743         }
  744 #ifdef SMP
  745         printf("cpuid = %d\n", PCPU_GET(cpuid));
  746 #endif
  747 
  748 #ifdef KDB
  749         if (newpanic && trace_on_panic)
  750                 kdb_backtrace();
  751         if (debugger_on_panic)
  752                 kdb_enter(KDB_WHY_PANIC, "panic");
  753 #endif
  754         /*thread_lock(td); */
  755         td->td_flags |= TDF_INPANIC;
  756         /* thread_unlock(td); */
  757         if (!sync_on_panic)
  758                 bootopt |= RB_NOSYNC;
  759         kern_reboot(bootopt);
  760 }
  761 
  762 /*
  763  * Support for poweroff delay.
  764  *
  765  * Please note that setting this delay too short might power off your machine
  766  * before the write cache on your hard disk has been flushed, leading to
  767  * soft-updates inconsistencies.
  768  */
  769 #ifndef POWEROFF_DELAY
  770 # define POWEROFF_DELAY 5000
  771 #endif
  772 static int poweroff_delay = POWEROFF_DELAY;
  773 
  774 SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
  775     &poweroff_delay, 0, "Delay before poweroff to write disk caches (msec)");
  776 
  777 static void
  778 poweroff_wait(void *junk, int howto)
  779 {
  780 
  781         if (!(howto & RB_POWEROFF) || poweroff_delay <= 0)
  782                 return;
  783         DELAY(poweroff_delay * 1000);
  784 }
  785 
  786 /*
  787  * Some system processes (e.g. syncer) need to be stopped at appropriate
  788  * points in their main loops prior to a system shutdown, so that they
  789  * won't interfere with the shutdown process (e.g. by holding a disk buf
  790  * to cause sync to fail).  For each of these system processes, register
  791  * shutdown_kproc() as a handler for one of shutdown events.
  792  */
  793 static int kproc_shutdown_wait = 60;
  794 SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
  795     &kproc_shutdown_wait, 0, "Max wait time (sec) to stop for each process");
  796 
  797 void
  798 kproc_shutdown(void *arg, int howto)
  799 {
  800         struct proc *p;
  801         int error;
  802 
  803         if (panicstr)
  804                 return;
  805 
  806         p = (struct proc *)arg;
  807         printf("Waiting (max %d seconds) for system process `%s' to stop...",
  808             kproc_shutdown_wait, p->p_comm);
  809         error = kproc_suspend(p, kproc_shutdown_wait * hz);
  810 
  811         if (error == EWOULDBLOCK)
  812                 printf("timed out\n");
  813         else
  814                 printf("done\n");
  815 }
  816 
  817 void
  818 kthread_shutdown(void *arg, int howto)
  819 {
  820         struct thread *td;
  821         int error;
  822 
  823         if (panicstr)
  824                 return;
  825 
  826         td = (struct thread *)arg;
  827         printf("Waiting (max %d seconds) for system thread `%s' to stop...",
  828             kproc_shutdown_wait, td->td_name);
  829         error = kthread_suspend(td, kproc_shutdown_wait * hz);
  830 
  831         if (error == EWOULDBLOCK)
  832                 printf("timed out\n");
  833         else
  834                 printf("done\n");
  835 }
  836 
  837 static char dumpdevname[sizeof(((struct cdev*)NULL)->si_name)];
  838 SYSCTL_STRING(_kern_shutdown, OID_AUTO, dumpdevname, CTLFLAG_RD,
  839     dumpdevname, 0, "Device for kernel dumps");
  840 
  841 /* Registration of dumpers */
  842 int
  843 set_dumper(struct dumperinfo *di, const char *devname)
  844 {
  845         size_t wantcopy;
  846 
  847         if (di == NULL) {
  848                 bzero(&dumper, sizeof dumper);
  849                 dumpdevname[0] = '\0';
  850                 return (0);
  851         }
  852         if (dumper.dumper != NULL)
  853                 return (EBUSY);
  854         dumper = *di;
  855         wantcopy = strlcpy(dumpdevname, devname, sizeof(dumpdevname));
  856         if (wantcopy >= sizeof(dumpdevname)) {
  857                 printf("set_dumper: device name truncated from '%s' -> '%s'\n",
  858                         devname, dumpdevname);
  859         }
  860         return (0);
  861 }
  862 
  863 /* Call dumper with bounds checking. */
  864 int
  865 dump_write(struct dumperinfo *di, void *virtual, vm_offset_t physical,
  866     off_t offset, size_t length)
  867 {
  868 
  869         if (length != 0 && (offset < di->mediaoffset ||
  870             offset - di->mediaoffset + length > di->mediasize)) {
  871                 printf("Attempt to write outside dump device boundaries.\n"
  872             "offset(%jd), mediaoffset(%jd), length(%ju), mediasize(%jd).\n",
  873                     (intmax_t)offset, (intmax_t)di->mediaoffset,
  874                     (uintmax_t)length, (intmax_t)di->mediasize);
  875                 return (ENOSPC);
  876         }
  877         return (di->dumper(di->priv, virtual, physical, offset, length));
  878 }
  879 
  880 void
  881 mkdumpheader(struct kerneldumpheader *kdh, char *magic, uint32_t archver,
  882     uint64_t dumplen, uint32_t blksz)
  883 {
  884 
  885         bzero(kdh, sizeof(*kdh));
  886         strncpy(kdh->magic, magic, sizeof(kdh->magic));
  887         strncpy(kdh->architecture, MACHINE_ARCH, sizeof(kdh->architecture));
  888         kdh->version = htod32(KERNELDUMPVERSION);
  889         kdh->architectureversion = htod32(archver);
  890         kdh->dumplength = htod64(dumplen);
  891         kdh->dumptime = htod64(time_second);
  892         kdh->blocksize = htod32(blksz);
  893         strncpy(kdh->hostname, prison0.pr_hostname, sizeof(kdh->hostname));
  894         strncpy(kdh->versionstring, version, sizeof(kdh->versionstring));
  895         if (panicstr != NULL)
  896                 strncpy(kdh->panicstring, panicstr, sizeof(kdh->panicstring));
  897         kdh->parity = kerneldump_parity(kdh);
  898 }

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