1 /*- 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * Copyright (c) 2005 Robert N. M. Watson 6 * All rights reserved. 7 * 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * Copyright (c) 1994 Christopher G. Demetriou 38 * 39 * Redistribution and use in source and binary forms, with or without 40 * modification, are permitted provided that the following conditions 41 * are met: 42 * 1. Redistributions of source code must retain the above copyright 43 * notice, this list of conditions and the following disclaimer. 44 * 2. Redistributions in binary form must reproduce the above copyright 45 * notice, this list of conditions and the following disclaimer in the 46 * documentation and/or other materials provided with the distribution. 47 * 3. All advertising materials mentioning features or use of this software 48 * must display the following acknowledgement: 49 * This product includes software developed by the University of 50 * California, Berkeley and its contributors. 51 * 4. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * @(#)kern_acct.c 8.1 (Berkeley) 6/14/93 68 */ 69 70 #include <sys/cdefs.h> 71 __FBSDID("$FreeBSD$"); 72 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/mount.h> 82 #include <sys/mutex.h> 83 #include <sys/namei.h> 84 #include <sys/priv.h> 85 #include <sys/proc.h> 86 #include <sys/resourcevar.h> 87 #include <sys/sched.h> 88 #include <sys/sx.h> 89 #include <sys/sysctl.h> 90 #include <sys/sysent.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 /* 99 * The routines implemented in this file are described in: 100 * Leffler, et al.: The Design and Implementation of the 4.3BSD 101 * UNIX Operating System (Addison Welley, 1989) 102 * on pages 62-63. 103 * On May 2007 the historic 3 bits base 8 exponent, 13 bit fraction 104 * compt_t representation described in the above reference was replaced 105 * with that of IEEE-754 floats. 106 * 107 * Arguably, to simplify accounting operations, this mechanism should 108 * be replaced by one in which an accounting log file (similar to /dev/klog) 109 * is read by a user process, etc. However, that has its own problems. 110 */ 111 112 /* Floating point definitions from <float.h>. */ 113 #define FLT_MANT_DIG 24 /* p */ 114 #define FLT_MAX_EXP 128 /* emax */ 115 116 /* 117 * Internal accounting functions. 118 * The former's operation is described in Leffler, et al., and the latter 119 * was provided by UCB with the 4.4BSD-Lite release 120 */ 121 static uint32_t encode_timeval(struct timeval); 122 static uint32_t encode_long(long); 123 static void acctwatch(void); 124 static void acct_thread(void *); 125 static int acct_disable(struct thread *, int); 126 127 /* 128 * Accounting vnode pointer, saved vnode pointer, and flags for each. 129 * acct_sx protects against changes to the active vnode and credentials 130 * while accounting records are being committed to disk. 131 */ 132 static int acct_configured; 133 static int acct_suspended; 134 static struct vnode *acct_vp; 135 static struct ucred *acct_cred; 136 static int acct_flags; 137 static struct sx acct_sx; 138 139 SX_SYSINIT(acct, &acct_sx, "acct_sx"); 140 141 /* 142 * State of the accounting kthread. 143 */ 144 static int acct_state; 145 146 #define ACCT_RUNNING 1 /* Accounting kthread is running. */ 147 #define ACCT_EXITREQ 2 /* Accounting kthread should exit. */ 148 149 /* 150 * Values associated with enabling and disabling accounting 151 */ 152 static int acctsuspend = 2; /* stop accounting when < 2% free space left */ 153 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW, 154 &acctsuspend, 0, "percentage of free disk space below which accounting stops"); 155 156 static int acctresume = 4; /* resume when free space risen to > 4% */ 157 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW, 158 &acctresume, 0, "percentage of free disk space above which accounting resumes"); 159 160 static int acctchkfreq = 15; /* frequency (in seconds) to check space */ 161 162 static int 163 sysctl_acct_chkfreq(SYSCTL_HANDLER_ARGS) 164 { 165 int error, value; 166 167 /* Write out the old value. */ 168 error = SYSCTL_OUT(req, &acctchkfreq, sizeof(int)); 169 if (error || req->newptr == NULL) 170 return (error); 171 172 /* Read in and verify the new value. */ 173 error = SYSCTL_IN(req, &value, sizeof(int)); 174 if (error) 175 return (error); 176 if (value <= 0) 177 return (EINVAL); 178 acctchkfreq = value; 179 return (0); 180 } 181 SYSCTL_PROC(_kern, OID_AUTO, acct_chkfreq, CTLTYPE_INT|CTLFLAG_RW, 182 &acctchkfreq, 0, sysctl_acct_chkfreq, "I", 183 "frequency for checking the free space"); 184 185 SYSCTL_INT(_kern, OID_AUTO, acct_configured, CTLFLAG_RD, &acct_configured, 0, 186 "Accounting configured or not"); 187 188 SYSCTL_INT(_kern, OID_AUTO, acct_suspended, CTLFLAG_RD, &acct_suspended, 0, 189 "Accounting suspended or not"); 190 191 /* 192 * Accounting system call. Written based on the specification and previous 193 * implementation done by Mark Tinguely. 194 */ 195 int 196 sys_acct(struct thread *td, struct acct_args *uap) 197 { 198 struct nameidata nd; 199 int error, flags, vfslocked, replacing; 200 201 error = priv_check(td, PRIV_ACCT); 202 if (error) 203 return (error); 204 205 /* 206 * If accounting is to be started to a file, open that file for 207 * appending and make sure it's a 'normal'. 208 */ 209 if (uap->path != NULL) { 210 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE | AUDITVNODE1, 211 UIO_USERSPACE, uap->path, td); 212 flags = FWRITE | O_APPEND; 213 error = vn_open(&nd, &flags, 0, NULL); 214 if (error) 215 return (error); 216 vfslocked = NDHASGIANT(&nd); 217 NDFREE(&nd, NDF_ONLY_PNBUF); 218 #ifdef MAC 219 error = mac_system_check_acct(td->td_ucred, nd.ni_vp); 220 if (error) { 221 VOP_UNLOCK(nd.ni_vp, 0); 222 vn_close(nd.ni_vp, flags, td->td_ucred, td); 223 VFS_UNLOCK_GIANT(vfslocked); 224 return (error); 225 } 226 #endif 227 VOP_UNLOCK(nd.ni_vp, 0); 228 if (nd.ni_vp->v_type != VREG) { 229 vn_close(nd.ni_vp, flags, td->td_ucred, td); 230 VFS_UNLOCK_GIANT(vfslocked); 231 return (EACCES); 232 } 233 VFS_UNLOCK_GIANT(vfslocked); 234 #ifdef MAC 235 } else { 236 error = mac_system_check_acct(td->td_ucred, NULL); 237 if (error) 238 return (error); 239 #endif 240 } 241 242 /* 243 * Disallow concurrent access to the accounting vnode while we swap 244 * it out, in order to prevent access after close. 245 */ 246 sx_xlock(&acct_sx); 247 248 /* 249 * Don't log spurious disable/enable messages if we are 250 * switching from one accounting file to another due to log 251 * rotation. 252 */ 253 replacing = (acct_vp != NULL && uap->path != NULL); 254 255 /* 256 * If accounting was previously enabled, kill the old space-watcher, 257 * close the file, and (if no new file was specified, leave). Reset 258 * the suspended state regardless of whether accounting remains 259 * enabled. 260 */ 261 acct_suspended = 0; 262 if (acct_vp != NULL) { 263 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 264 error = acct_disable(td, !replacing); 265 VFS_UNLOCK_GIANT(vfslocked); 266 } 267 if (uap->path == NULL) { 268 if (acct_state & ACCT_RUNNING) { 269 acct_state |= ACCT_EXITREQ; 270 wakeup(&acct_state); 271 } 272 sx_xunlock(&acct_sx); 273 return (error); 274 } 275 276 /* 277 * Save the new accounting file vnode, and schedule the new 278 * free space watcher. 279 */ 280 acct_vp = nd.ni_vp; 281 acct_cred = crhold(td->td_ucred); 282 acct_flags = flags; 283 if (acct_state & ACCT_RUNNING) 284 acct_state &= ~ACCT_EXITREQ; 285 else { 286 /* 287 * Try to start up an accounting kthread. We may start more 288 * than one, but if so the extras will commit suicide as 289 * soon as they start up. 290 */ 291 error = kproc_create(acct_thread, NULL, NULL, 0, 0, 292 "accounting"); 293 if (error) { 294 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 295 (void) vn_close(acct_vp, acct_flags, acct_cred, td); 296 VFS_UNLOCK_GIANT(vfslocked); 297 crfree(acct_cred); 298 acct_configured = 0; 299 acct_vp = NULL; 300 acct_cred = NULL; 301 acct_flags = 0; 302 sx_xunlock(&acct_sx); 303 log(LOG_NOTICE, "Unable to start accounting thread\n"); 304 return (error); 305 } 306 } 307 acct_configured = 1; 308 sx_xunlock(&acct_sx); 309 if (!replacing) 310 log(LOG_NOTICE, "Accounting enabled\n"); 311 return (error); 312 } 313 314 /* 315 * Disable currently in-progress accounting by closing the vnode, dropping 316 * our reference to the credential, and clearing the vnode's flags. 317 */ 318 static int 319 acct_disable(struct thread *td, int logging) 320 { 321 int error; 322 323 sx_assert(&acct_sx, SX_XLOCKED); 324 error = vn_close(acct_vp, acct_flags, acct_cred, td); 325 crfree(acct_cred); 326 acct_configured = 0; 327 acct_vp = NULL; 328 acct_cred = NULL; 329 acct_flags = 0; 330 if (logging) 331 log(LOG_NOTICE, "Accounting disabled\n"); 332 return (error); 333 } 334 335 /* 336 * Write out process accounting information, on process exit. 337 * Data to be written out is specified in Leffler, et al. 338 * and are enumerated below. (They're also noted in the system 339 * "acct.h" header file.) 340 */ 341 int 342 acct_process(struct thread *td) 343 { 344 struct acctv2 acct; 345 struct timeval ut, st, tmp; 346 struct plimit *newlim, *oldlim; 347 struct proc *p; 348 struct rusage ru; 349 int t, ret, vfslocked; 350 351 /* 352 * Lockless check of accounting condition before doing the hard 353 * work. 354 */ 355 if (acct_vp == NULL || acct_suspended) 356 return (0); 357 358 sx_slock(&acct_sx); 359 360 /* 361 * If accounting isn't enabled, don't bother. Have to check again 362 * once we own the lock in case we raced with disabling of accounting 363 * by another thread. 364 */ 365 if (acct_vp == NULL || acct_suspended) { 366 sx_sunlock(&acct_sx); 367 return (0); 368 } 369 370 p = td->td_proc; 371 372 /* 373 * Get process accounting information. 374 */ 375 376 sx_slock(&proctree_lock); 377 PROC_LOCK(p); 378 379 /* (1) The terminal from which the process was started */ 380 if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp) 381 acct.ac_tty = tty_udev(p->p_pgrp->pg_session->s_ttyp); 382 else 383 acct.ac_tty = NODEV; 384 sx_sunlock(&proctree_lock); 385 386 /* (2) The name of the command that ran */ 387 bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm); 388 389 /* (3) The amount of user and system time that was used */ 390 rufetchcalc(p, &ru, &ut, &st); 391 acct.ac_utime = encode_timeval(ut); 392 acct.ac_stime = encode_timeval(st); 393 394 /* (4) The elapsed time the command ran (and its starting time) */ 395 tmp = boottime; 396 timevaladd(&tmp, &p->p_stats->p_start); 397 acct.ac_btime = tmp.tv_sec; 398 microuptime(&tmp); 399 timevalsub(&tmp, &p->p_stats->p_start); 400 acct.ac_etime = encode_timeval(tmp); 401 402 /* (5) The average amount of memory used */ 403 tmp = ut; 404 timevaladd(&tmp, &st); 405 /* Convert tmp (i.e. u + s) into hz units to match ru_i*. */ 406 t = tmp.tv_sec * hz + tmp.tv_usec / tick; 407 if (t) 408 acct.ac_mem = encode_long((ru.ru_ixrss + ru.ru_idrss + 409 + ru.ru_isrss) / t); 410 else 411 acct.ac_mem = 0; 412 413 /* (6) The number of disk I/O operations done */ 414 acct.ac_io = encode_long(ru.ru_inblock + ru.ru_oublock); 415 416 /* (7) The UID and GID of the process */ 417 acct.ac_uid = p->p_ucred->cr_ruid; 418 acct.ac_gid = p->p_ucred->cr_rgid; 419 420 /* (8) The boolean flags that tell how the process terminated, etc. */ 421 acct.ac_flagx = p->p_acflag; 422 PROC_UNLOCK(p); 423 424 /* Setup ancillary structure fields. */ 425 acct.ac_flagx |= ANVER; 426 acct.ac_zero = 0; 427 acct.ac_version = 2; 428 acct.ac_len = acct.ac_len2 = sizeof(acct); 429 430 /* 431 * Eliminate any file size rlimit. 432 */ 433 newlim = lim_alloc(); 434 PROC_LOCK(p); 435 oldlim = p->p_limit; 436 lim_copy(newlim, oldlim); 437 newlim->pl_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY; 438 p->p_limit = newlim; 439 PROC_UNLOCK(p); 440 lim_free(oldlim); 441 442 /* 443 * Write the accounting information to the file. 444 */ 445 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 446 ret = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct, sizeof (acct), 447 (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, acct_cred, NOCRED, 448 NULL, td); 449 VFS_UNLOCK_GIANT(vfslocked); 450 sx_sunlock(&acct_sx); 451 return (ret); 452 } 453 454 /* FLOAT_CONVERSION_START (Regression testing; don't remove this line.) */ 455 456 /* Convert timevals and longs into IEEE-754 bit patterns. */ 457 458 /* Mantissa mask (MSB is implied, so subtract 1). */ 459 #define MANT_MASK ((1 << (FLT_MANT_DIG - 1)) - 1) 460 461 /* 462 * We calculate integer values to a precision of approximately 463 * 28 bits. 464 * This is high-enough precision to fill the 24 float bits 465 * and low-enough to avoid overflowing the 32 int bits. 466 */ 467 #define CALC_BITS 28 468 469 /* log_2(1000000). */ 470 #define LOG2_1M 20 471 472 /* 473 * Convert the elements of a timeval into a 32-bit word holding 474 * the bits of a IEEE-754 float. 475 * The float value represents the timeval's value in microsecond units. 476 */ 477 static uint32_t 478 encode_timeval(struct timeval tv) 479 { 480 int log2_s; 481 int val, exp; /* Unnormalized value and exponent */ 482 int norm_exp; /* Normalized exponent */ 483 int shift; 484 485 /* 486 * First calculate value and exponent to about CALC_BITS precision. 487 * Note that the following conditionals have been ordered so that 488 * the most common cases appear first. 489 */ 490 if (tv.tv_sec == 0) { 491 if (tv.tv_usec == 0) 492 return (0); 493 exp = 0; 494 val = tv.tv_usec; 495 } else { 496 /* 497 * Calculate the value to a precision of approximately 498 * CALC_BITS. 499 */ 500 log2_s = fls(tv.tv_sec) - 1; 501 if (log2_s + LOG2_1M < CALC_BITS) { 502 exp = 0; 503 val = 1000000 * tv.tv_sec + tv.tv_usec; 504 } else { 505 exp = log2_s + LOG2_1M - CALC_BITS; 506 val = (unsigned int)(((uint64_t)1000000 * tv.tv_sec + 507 tv.tv_usec) >> exp); 508 } 509 } 510 /* Now normalize and pack the value into an IEEE-754 float. */ 511 norm_exp = fls(val) - 1; 512 shift = FLT_MANT_DIG - norm_exp - 1; 513 #ifdef ACCT_DEBUG 514 printf("val=%d exp=%d shift=%d log2(val)=%d\n", 515 val, exp, shift, norm_exp); 516 printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp, 517 ((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK)); 518 #endif 519 return (((FLT_MAX_EXP - 1 + exp + norm_exp) << (FLT_MANT_DIG - 1)) | 520 ((shift > 0 ? val << shift : val >> -shift) & MANT_MASK)); 521 } 522 523 /* 524 * Convert a non-negative long value into the bit pattern of 525 * an IEEE-754 float value. 526 */ 527 static uint32_t 528 encode_long(long val) 529 { 530 int norm_exp; /* Normalized exponent */ 531 int shift; 532 533 if (val == 0) 534 return (0); 535 if (val < 0) { 536 log(LOG_NOTICE, 537 "encode_long: negative value %ld in accounting record\n", 538 val); 539 val = LONG_MAX; 540 } 541 norm_exp = fls(val) - 1; 542 shift = FLT_MANT_DIG - norm_exp - 1; 543 #ifdef ACCT_DEBUG 544 printf("val=%d shift=%d log2(val)=%d\n", 545 val, shift, norm_exp); 546 printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp, 547 ((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK)); 548 #endif 549 return (((FLT_MAX_EXP - 1 + norm_exp) << (FLT_MANT_DIG - 1)) | 550 ((shift > 0 ? val << shift : val >> -shift) & MANT_MASK)); 551 } 552 553 /* FLOAT_CONVERSION_END (Regression testing; don't remove this line.) */ 554 555 /* 556 * Periodically check the filesystem to see if accounting 557 * should be turned on or off. Beware the case where the vnode 558 * has been vgone()'d out from underneath us, e.g. when the file 559 * system containing the accounting file has been forcibly unmounted. 560 */ 561 /* ARGSUSED */ 562 static void 563 acctwatch(void) 564 { 565 struct statfs sb; 566 int vfslocked; 567 568 sx_assert(&acct_sx, SX_XLOCKED); 569 570 /* 571 * If accounting was disabled before our kthread was scheduled, 572 * then acct_vp might be NULL. If so, just ask our kthread to 573 * exit and return. 574 */ 575 if (acct_vp == NULL) { 576 acct_state |= ACCT_EXITREQ; 577 return; 578 } 579 580 /* 581 * If our vnode is no longer valid, tear it down and signal the 582 * accounting thread to die. 583 */ 584 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount); 585 if (acct_vp->v_type == VBAD) { 586 (void) acct_disable(NULL, 1); 587 VFS_UNLOCK_GIANT(vfslocked); 588 acct_state |= ACCT_EXITREQ; 589 return; 590 } 591 592 /* 593 * Stopping here is better than continuing, maybe it will be VBAD 594 * next time around. 595 */ 596 if (VFS_STATFS(acct_vp->v_mount, &sb) < 0) { 597 VFS_UNLOCK_GIANT(vfslocked); 598 return; 599 } 600 VFS_UNLOCK_GIANT(vfslocked); 601 if (acct_suspended) { 602 if (sb.f_bavail > (int64_t)(acctresume * sb.f_blocks / 603 100)) { 604 acct_suspended = 0; 605 log(LOG_NOTICE, "Accounting resumed\n"); 606 } 607 } else { 608 if (sb.f_bavail <= (int64_t)(acctsuspend * sb.f_blocks / 609 100)) { 610 acct_suspended = 1; 611 log(LOG_NOTICE, "Accounting suspended\n"); 612 } 613 } 614 } 615 616 /* 617 * The main loop for the dedicated kernel thread that periodically calls 618 * acctwatch(). 619 */ 620 static void 621 acct_thread(void *dummy) 622 { 623 u_char pri; 624 625 /* This is a low-priority kernel thread. */ 626 pri = PRI_MAX_KERN; 627 thread_lock(curthread); 628 sched_prio(curthread, pri); 629 thread_unlock(curthread); 630 631 /* If another accounting kthread is already running, just die. */ 632 sx_xlock(&acct_sx); 633 if (acct_state & ACCT_RUNNING) { 634 sx_xunlock(&acct_sx); 635 kproc_exit(0); 636 } 637 acct_state |= ACCT_RUNNING; 638 639 /* Loop until we are asked to exit. */ 640 while (!(acct_state & ACCT_EXITREQ)) { 641 642 /* Perform our periodic checks. */ 643 acctwatch(); 644 645 /* 646 * We check this flag again before sleeping since the 647 * acctwatch() might have shut down accounting and asked us 648 * to exit. 649 */ 650 if (!(acct_state & ACCT_EXITREQ)) { 651 sx_sleep(&acct_state, &acct_sx, 0, "-", 652 acctchkfreq * hz); 653 } 654 } 655 656 /* 657 * Acknowledge the exit request and shutdown. We clear both the 658 * exit request and running flags. 659 */ 660 acct_state = 0; 661 sx_xunlock(&acct_sx); 662 kproc_exit(0); 663 } 664