1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1982, 1986, 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * Copyright (c) 2005 Robert N. M. Watson 8 * All rights reserved. 9 * 10 * All or some portions of this file are derived from material licensed 11 * to the University of California by American Telephone and Telegraph 12 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 13 * the permission of UNIX System Laboratories, Inc. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * Copyright (c) 1994 Christopher G. Demetriou 40 * 41 * Redistribution and use in source and binary forms, with or without 42 * modification, are permitted provided that the following conditions 43 * are met: 44 * 1. Redistributions of source code must retain the above copyright 45 * notice, this list of conditions and the following disclaimer. 46 * 2. Redistributions in binary form must reproduce the above copyright 47 * notice, this list of conditions and the following disclaimer in the 48 * documentation and/or other materials provided with the distribution. 49 * 3. All advertising materials mentioning features or use of this software 50 * must display the following acknowledgement: 51 * This product includes software developed by the University of 52 * California, Berkeley and its contributors. 53 * 4. Neither the name of the University nor the names of its contributors 54 * may be used to endorse or promote products derived from this software 55 * without specific prior written permission. 56 * 57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 67 * SUCH DAMAGE. 68 * 69 * @(#)kern_acct.c 8.1 (Berkeley) 6/14/93 70 */ 71 72 #include <sys/cdefs.h> 73 #include <sys/param.h> 74 #include <sys/systm.h> 75 #include <sys/acct.h> 76 #include <sys/fcntl.h> 77 #include <sys/kernel.h> 78 #include <sys/kthread.h> 79 #include <sys/limits.h> 80 #include <sys/lock.h> 81 #include <sys/malloc.h> 82 #include <sys/mount.h> 83 #include <sys/mutex.h> 84 #include <sys/namei.h> 85 #include <sys/priv.h> 86 #include <sys/proc.h> 87 #include <sys/resourcevar.h> 88 #include <sys/sched.h> 89 #include <sys/sx.h> 90 #include <sys/sysctl.h> 91 #include <sys/syslog.h> 92 #include <sys/sysproto.h> 93 #include <sys/tty.h> 94 #include <sys/vnode.h> 95 96 #include <security/mac/mac_framework.h> 97 98 _Static_assert(sizeof(struct acctv3) - offsetof(struct acctv3, ac_trailer) == 99 sizeof(struct acctv2) - offsetof(struct acctv2, ac_trailer), "trailer"); 100 _Static_assert(sizeof(struct acctv3) - offsetof(struct acctv3, ac_len2) == 101 sizeof(struct acctv2) - offsetof(struct acctv2, ac_len2), "len2"); 102 103 /* 104 * The routines implemented in this file are described in: 105 * Leffler, et al.: The Design and Implementation of the 4.3BSD 106 * UNIX Operating System (Addison Welley, 1989) 107 * on pages 62-63. 108 * On May 2007 the historic 3 bits base 8 exponent, 13 bit fraction 109 * compt_t representation described in the above reference was replaced 110 * with that of IEEE-754 floats. 111 * 112 * Arguably, to simplify accounting operations, this mechanism should 113 * be replaced by one in which an accounting log file (similar to /dev/klog) 114 * is read by a user process, etc. However, that has its own problems. 115 */ 116 117 /* Floating point definitions from <float.h>. */ 118 #define FLT_MANT_DIG 24 /* p */ 119 #define FLT_MAX_EXP 128 /* emax */ 120 121 /* 122 * Internal accounting functions. 123 * The former's operation is described in Leffler, et al., and the latter 124 * was provided by UCB with the 4.4BSD-Lite release 125 */ 126 static uint32_t encode_timeval(struct timeval); 127 static uint32_t encode_long(long); 128 static void acctwatch(void); 129 static void acct_thread(void *); 130 static int acct_disable(struct thread *, int); 131 132 /* 133 * Accounting vnode pointer, saved vnode pointer, and flags for each. 134 * acct_sx protects against changes to the active vnode and credentials 135 * while accounting records are being committed to disk. 136 */ 137 static int acct_configured; 138 static int acct_suspended; 139 static struct vnode *acct_vp; 140 static struct ucred *acct_cred; 141 static int acct_flags; 142 static struct sx acct_sx; 143 144 SX_SYSINIT(acct, &acct_sx, "acct_sx"); 145 146 /* 147 * State of the accounting kthread. 148 */ 149 static int acct_state; 150 151 #define ACCT_RUNNING 1 /* Accounting kthread is running. */ 152 #define ACCT_EXITREQ 2 /* Accounting kthread should exit. */ 153 154 /* 155 * Values associated with enabling and disabling accounting 156 */ 157 static int acctsuspend = 2; /* stop accounting when < 2% free space left */ 158 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW, 159 &acctsuspend, 0, "percentage of free disk space below which accounting stops"); 160 161 static int acctresume = 4; /* resume when free space risen to > 4% */ 162 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW, 163 &acctresume, 0, "percentage of free disk space above which accounting resumes"); 164 165 static int acctchkfreq = 15; /* frequency (in seconds) to check space */ 166 167 static int 168 sysctl_acct_chkfreq(SYSCTL_HANDLER_ARGS) 169 { 170 int error, value; 171 172 /* Write out the old value. */ 173 error = SYSCTL_OUT(req, &acctchkfreq, sizeof(int)); 174 if (error || req->newptr == NULL) 175 return (error); 176 177 /* Read in and verify the new value. */ 178 error = SYSCTL_IN(req, &value, sizeof(int)); 179 if (error) 180 return (error); 181 if (value <= 0) 182 return (EINVAL); 183 acctchkfreq = value; 184 return (0); 185 } 186 SYSCTL_PROC(_kern, OID_AUTO, acct_chkfreq, 187 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, &acctchkfreq, 0, 188 sysctl_acct_chkfreq, "I", 189 "frequency for checking the free space"); 190 191 SYSCTL_INT(_kern, OID_AUTO, acct_configured, CTLFLAG_RD, &acct_configured, 0, 192 "Accounting configured or not"); 193 194 SYSCTL_INT(_kern, OID_AUTO, acct_suspended, CTLFLAG_RD, &acct_suspended, 0, 195 "Accounting suspended or not"); 196 197 /* 198 * Accounting system call. Written based on the specification and previous 199 * implementation done by Mark Tinguely. 200 */ 201 int 202 sys_acct(struct thread *td, struct acct_args *uap) 203 { 204 struct nameidata nd; 205 int error, flags, replacing; 206 207 error = priv_check(td, PRIV_ACCT); 208 if (error) 209 return (error); 210 211 /* 212 * If accounting is to be started to a file, open that file for 213 * appending and make sure it's a 'normal'. 214 */ 215 if (uap->path != NULL) { 216 NDINIT(&nd, LOOKUP, NOFOLLOW | AUDITVNODE1, UIO_USERSPACE, 217 uap->path); 218 flags = FWRITE | O_APPEND; 219 error = vn_open(&nd, &flags, 0, NULL); 220 if (error) 221 return (error); 222 NDFREE_PNBUF(&nd); 223 #ifdef MAC 224 error = mac_system_check_acct(td->td_ucred, nd.ni_vp); 225 if (error) { 226 VOP_UNLOCK(nd.ni_vp); 227 vn_close(nd.ni_vp, flags, td->td_ucred, td); 228 return (error); 229 } 230 #endif 231 VOP_UNLOCK(nd.ni_vp); 232 if (nd.ni_vp->v_type != VREG) { 233 vn_close(nd.ni_vp, flags, td->td_ucred, td); 234 return (EACCES); 235 } 236 #ifdef MAC 237 } else { 238 error = mac_system_check_acct(td->td_ucred, NULL); 239 if (error) 240 return (error); 241 #endif 242 } 243 244 /* 245 * Disallow concurrent access to the accounting vnode while we swap 246 * it out, in order to prevent access after close. 247 */ 248 sx_xlock(&acct_sx); 249 250 /* 251 * Don't log spurious disable/enable messages if we are 252 * switching from one accounting file to another due to log 253 * rotation. 254 */ 255 replacing = (acct_vp != NULL && uap->path != NULL); 256 257 /* 258 * If accounting was previously enabled, kill the old space-watcher, 259 * close the file, and (if no new file was specified, leave). Reset 260 * the suspended state regardless of whether accounting remains 261 * enabled. 262 */ 263 acct_suspended = 0; 264 if (acct_vp != NULL) 265 error = acct_disable(td, !replacing); 266 if (uap->path == NULL) { 267 if (acct_state & ACCT_RUNNING) { 268 acct_state |= ACCT_EXITREQ; 269 wakeup(&acct_state); 270 } 271 sx_xunlock(&acct_sx); 272 return (error); 273 } 274 275 /* 276 * Save the new accounting file vnode, and schedule the new 277 * free space watcher. 278 */ 279 acct_vp = nd.ni_vp; 280 acct_cred = crhold(td->td_ucred); 281 acct_flags = flags; 282 if (acct_state & ACCT_RUNNING) 283 acct_state &= ~ACCT_EXITREQ; 284 else { 285 /* 286 * Try to start up an accounting kthread. We may start more 287 * than one, but if so the extras will commit suicide as 288 * soon as they start up. 289 */ 290 error = kproc_create(acct_thread, NULL, NULL, 0, 0, 291 "accounting"); 292 if (error) { 293 (void) acct_disable(td, 0); 294 sx_xunlock(&acct_sx); 295 log(LOG_NOTICE, "Unable to start accounting thread\n"); 296 return (error); 297 } 298 } 299 acct_configured = 1; 300 sx_xunlock(&acct_sx); 301 if (!replacing) 302 log(LOG_NOTICE, "Accounting enabled\n"); 303 return (error); 304 } 305 306 /* 307 * Disable currently in-progress accounting by closing the vnode, dropping 308 * our reference to the credential, and clearing the vnode's flags. 309 */ 310 static int 311 acct_disable(struct thread *td, int logging) 312 { 313 int error; 314 315 sx_assert(&acct_sx, SX_XLOCKED); 316 error = vn_close(acct_vp, acct_flags, acct_cred, td); 317 crfree(acct_cred); 318 acct_configured = 0; 319 acct_vp = NULL; 320 acct_cred = NULL; 321 acct_flags = 0; 322 if (logging) 323 log(LOG_NOTICE, "Accounting disabled\n"); 324 return (error); 325 } 326 327 /* 328 * Write out process accounting information, on process exit. 329 * Data to be written out is specified in Leffler, et al. 330 * and are enumerated below. (They're also noted in the system 331 * "acct.h" header file.) 332 */ 333 int 334 acct_process(struct thread *td) 335 { 336 struct acctv3 acct; 337 struct timeval ut, st, tmp; 338 struct proc *p; 339 struct rusage ru; 340 int t, ret; 341 342 /* 343 * Lockless check of accounting condition before doing the hard 344 * work. 345 */ 346 if (acct_vp == NULL || acct_suspended) 347 return (0); 348 349 memset(&acct, 0, sizeof(acct)); 350 351 sx_slock(&acct_sx); 352 353 /* 354 * If accounting isn't enabled, don't bother. Have to check again 355 * once we own the lock in case we raced with disabling of accounting 356 * by another thread. 357 */ 358 if (acct_vp == NULL || acct_suspended) { 359 sx_sunlock(&acct_sx); 360 return (0); 361 } 362 363 p = td->td_proc; 364 td->td_pflags2 |= TDP2_ACCT; 365 366 /* 367 * Get process accounting information. 368 */ 369 370 sx_slock(&proctree_lock); 371 PROC_LOCK(p); 372 373 /* (1) The terminal from which the process was started */ 374 if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp) 375 acct.ac_tty = tty_udev(p->p_pgrp->pg_session->s_ttyp); 376 else 377 acct.ac_tty = NODEV; 378 sx_sunlock(&proctree_lock); 379 380 /* (2) The name of the command that ran */ 381 bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm); 382 383 /* (3) The amount of user and system time that was used */ 384 rufetchcalc(p, &ru, &ut, &st); 385 acct.ac_utime = encode_timeval(ut); 386 acct.ac_stime = encode_timeval(st); 387 388 /* (4) The elapsed time the command ran (and its starting time) */ 389 getboottime(&tmp); 390 timevaladd(&tmp, &p->p_stats->p_start); 391 acct.ac_btime = tmp.tv_sec; 392 microuptime(&tmp); 393 timevalsub(&tmp, &p->p_stats->p_start); 394 acct.ac_etime = encode_timeval(tmp); 395 396 /* (5) The average amount of memory used */ 397 tmp = ut; 398 timevaladd(&tmp, &st); 399 /* Convert tmp (i.e. u + s) into hz units to match ru_i*. */ 400 t = tmp.tv_sec * hz + tmp.tv_usec / tick; 401 if (t) 402 acct.ac_mem = encode_long((ru.ru_ixrss + ru.ru_idrss + 403 + ru.ru_isrss) / t); 404 else 405 acct.ac_mem = 0; 406 407 /* (6) The number of disk I/O operations done */ 408 acct.ac_io = encode_long(ru.ru_inblock + ru.ru_oublock); 409 410 /* (7) The UID and GID of the process */ 411 acct.ac_uid = p->p_ucred->cr_ruid; 412 acct.ac_gid = p->p_ucred->cr_rgid; 413 414 /* (8) The boolean flags that tell how the process terminated, etc. */ 415 acct.ac_flagx = p->p_acflag; 416 417 PROC_UNLOCK(p); 418 419 /* Setup ancillary structure fields. */ 420 acct.ac_flagx |= ANVER; 421 acct.ac_zero = 0; 422 acct.ac_version = 3; 423 acct.ac_len = acct.ac_len2 = sizeof(acct); 424 425 /* 426 * Write the accounting information to the file. 427 */ 428 ret = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct, sizeof (acct), 429 (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, acct_cred, NOCRED, 430 NULL, td); 431 sx_sunlock(&acct_sx); 432 td->td_pflags2 &= ~TDP2_ACCT; 433 return (ret); 434 } 435 436 /* FLOAT_CONVERSION_START (Regression testing; don't remove this line.) */ 437 438 /* Convert timevals and longs into IEEE-754 bit patterns. */ 439 440 /* Mantissa mask (MSB is implied, so subtract 1). */ 441 #define MANT_MASK ((1 << (FLT_MANT_DIG - 1)) - 1) 442 443 /* 444 * We calculate integer values to a precision of approximately 445 * 28 bits. 446 * This is high-enough precision to fill the 24 float bits 447 * and low-enough to avoid overflowing the 32 int bits. 448 */ 449 #define CALC_BITS 28 450 451 /* log_2(1000000). */ 452 #define LOG2_1M 20 453 454 /* 455 * Convert the elements of a timeval into a 32-bit word holding 456 * the bits of a IEEE-754 float. 457 * The float value represents the timeval's value in microsecond units. 458 */ 459 static uint32_t 460 encode_timeval(struct timeval tv) 461 { 462 int log2_s; 463 int val, exp; /* Unnormalized value and exponent */ 464 int norm_exp; /* Normalized exponent */ 465 int shift; 466 467 /* 468 * First calculate value and exponent to about CALC_BITS precision. 469 * Note that the following conditionals have been ordered so that 470 * the most common cases appear first. 471 */ 472 if (tv.tv_sec == 0) { 473 if (tv.tv_usec == 0) 474 return (0); 475 exp = 0; 476 val = tv.tv_usec; 477 } else { 478 /* 479 * Calculate the value to a precision of approximately 480 * CALC_BITS. 481 */ 482 log2_s = fls(tv.tv_sec) - 1; 483 if (log2_s + LOG2_1M < CALC_BITS) { 484 exp = 0; 485 val = 1000000 * tv.tv_sec + tv.tv_usec; 486 } else { 487 exp = log2_s + LOG2_1M - CALC_BITS; 488 val = (unsigned int)(((uint64_t)1000000 * tv.tv_sec + 489 tv.tv_usec) >> exp); 490 } 491 } 492 /* Now normalize and pack the value into an IEEE-754 float. */ 493 norm_exp = fls(val) - 1; 494 shift = FLT_MANT_DIG - norm_exp - 1; 495 #ifdef ACCT_DEBUG 496 printf("val=%d exp=%d shift=%d log2(val)=%d\n", 497 val, exp, shift, norm_exp); 498 printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp, 499 ((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK)); 500 #endif 501 return (((FLT_MAX_EXP - 1 + exp + norm_exp) << (FLT_MANT_DIG - 1)) | 502 ((shift > 0 ? val << shift : val >> -shift) & MANT_MASK)); 503 } 504 505 /* 506 * Convert a non-negative long value into the bit pattern of 507 * an IEEE-754 float value. 508 */ 509 static uint32_t 510 encode_long(long val) 511 { 512 int norm_exp; /* Normalized exponent */ 513 int shift; 514 515 if (val == 0) 516 return (0); 517 if (val < 0) { 518 log(LOG_NOTICE, 519 "encode_long: negative value %ld in accounting record\n", 520 val); 521 val = LONG_MAX; 522 } 523 norm_exp = fls(val) - 1; 524 shift = FLT_MANT_DIG - norm_exp - 1; 525 #ifdef ACCT_DEBUG 526 printf("val=%d shift=%d log2(val)=%d\n", 527 val, shift, norm_exp); 528 printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp, 529 ((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK)); 530 #endif 531 return (((FLT_MAX_EXP - 1 + norm_exp) << (FLT_MANT_DIG - 1)) | 532 ((shift > 0 ? val << shift : val >> -shift) & MANT_MASK)); 533 } 534 535 /* FLOAT_CONVERSION_END (Regression testing; don't remove this line.) */ 536 537 /* 538 * Periodically check the filesystem to see if accounting 539 * should be turned on or off. Beware the case where the vnode 540 * has been vgone()'d out from underneath us, e.g. when the file 541 * system containing the accounting file has been forcibly unmounted. 542 */ 543 /* ARGSUSED */ 544 static void 545 acctwatch(void) 546 { 547 struct statfs *sp; 548 549 sx_assert(&acct_sx, SX_XLOCKED); 550 551 /* 552 * If accounting was disabled before our kthread was scheduled, 553 * then acct_vp might be NULL. If so, just ask our kthread to 554 * exit and return. 555 */ 556 if (acct_vp == NULL) { 557 acct_state |= ACCT_EXITREQ; 558 return; 559 } 560 561 /* 562 * If our vnode is no longer valid, tear it down and signal the 563 * accounting thread to die. 564 */ 565 if (acct_vp->v_type == VBAD) { 566 (void) acct_disable(NULL, 1); 567 acct_state |= ACCT_EXITREQ; 568 return; 569 } 570 571 /* 572 * Stopping here is better than continuing, maybe it will be VBAD 573 * next time around. 574 */ 575 sp = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK); 576 if (VFS_STATFS(acct_vp->v_mount, sp) < 0) { 577 free(sp, M_STATFS); 578 return; 579 } 580 if (acct_suspended) { 581 if (sp->f_bavail > (int64_t)(acctresume * sp->f_blocks / 582 100)) { 583 acct_suspended = 0; 584 log(LOG_NOTICE, "Accounting resumed\n"); 585 } 586 } else { 587 if (sp->f_bavail <= (int64_t)(acctsuspend * sp->f_blocks / 588 100)) { 589 acct_suspended = 1; 590 log(LOG_NOTICE, "Accounting suspended\n"); 591 } 592 } 593 free(sp, M_STATFS); 594 } 595 596 /* 597 * The main loop for the dedicated kernel thread that periodically calls 598 * acctwatch(). 599 */ 600 static void 601 acct_thread(void *dummy) 602 { 603 u_char pri; 604 605 /* This is a low-priority kernel thread. */ 606 pri = PRI_MAX_KERN; 607 thread_lock(curthread); 608 sched_prio(curthread, pri); 609 thread_unlock(curthread); 610 611 /* If another accounting kthread is already running, just die. */ 612 sx_xlock(&acct_sx); 613 if (acct_state & ACCT_RUNNING) { 614 sx_xunlock(&acct_sx); 615 kproc_exit(0); 616 } 617 acct_state |= ACCT_RUNNING; 618 619 /* Loop until we are asked to exit. */ 620 while (!(acct_state & ACCT_EXITREQ)) { 621 /* Perform our periodic checks. */ 622 acctwatch(); 623 624 /* 625 * We check this flag again before sleeping since the 626 * acctwatch() might have shut down accounting and asked us 627 * to exit. 628 */ 629 if (!(acct_state & ACCT_EXITREQ)) { 630 sx_sleep(&acct_state, &acct_sx, 0, "-", 631 acctchkfreq * hz); 632 } 633 } 634 635 /* 636 * Acknowledge the exit request and shutdown. We clear both the 637 * exit request and running flags. 638 */ 639 acct_state = 0; 640 sx_xunlock(&acct_sx); 641 kproc_exit(0); 642 } 643