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


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

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

Version: -  FREEBSD  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-2  -  FREEBSD-11-1  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-4  -  FREEBSD-10-3  -  FREEBSD-10-2  -  FREEBSD-10-1  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-3  -  FREEBSD-9-2  -  FREEBSD-9-1  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-4  -  FREEBSD-8-3  -  FREEBSD-8-2  -  FREEBSD-8-1  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-4  -  FREEBSD-7-3  -  FREEBSD-7-2  -  FREEBSD-7-1  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-4  -  FREEBSD-6-3  -  FREEBSD-6-2  -  FREEBSD-6-1  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-5  -  FREEBSD-5-4  -  FREEBSD-5-3  -  FREEBSD-5-2  -  FREEBSD-5-1  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  linux-2.6  -  linux-2.4.22  -  MK83  -  MK84  -  PLAN9  -  DFBSD  -  NETBSD  -  NETBSD5  -  NETBSD4  -  NETBSD3  -  NETBSD20  -  OPENBSD  -  xnu-517  -  xnu-792  -  xnu-792.6.70  -  xnu-1228  -  xnu-1456.1.26  -  xnu-1699.24.8  -  xnu-2050.18.24  -  OPENSOLARIS  -  minix-3-1-1 
SearchContext: -  none  -  3  -  10 

    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 "opt_mac.h"
   74 
   75 #include <sys/param.h>
   76 #include <sys/systm.h>
   77 #include <sys/acct.h>
   78 #include <sys/fcntl.h>
   79 #include <sys/kernel.h>
   80 #include <sys/kthread.h>
   81 #include <sys/limits.h>
   82 #include <sys/lock.h>
   83 #include <sys/mount.h>
   84 #include <sys/mutex.h>
   85 #include <sys/namei.h>
   86 #include <sys/priv.h>
   87 #include <sys/proc.h>
   88 #include <sys/resourcevar.h>
   89 #include <sys/sched.h>
   90 #include <sys/sx.h>
   91 #include <sys/sysctl.h>
   92 #include <sys/sysent.h>
   93 #include <sys/syslog.h>
   94 #include <sys/sysproto.h>
   95 #include <sys/tty.h>
   96 #include <sys/vnode.h>
   97 
   98 #include <security/mac/mac_framework.h>
   99 
  100 /*
  101  * The routines implemented in this file are described in:
  102  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
  103  *          UNIX Operating System (Addison Welley, 1989)
  104  * on pages 62-63.
  105  * On May 2007 the historic 3 bits base 8 exponent, 13 bit fraction
  106  * compt_t representation described in the above reference was replaced
  107  * with that of IEEE-754 floats.
  108  *
  109  * Arguably, to simplify accounting operations, this mechanism should
  110  * be replaced by one in which an accounting log file (similar to /dev/klog)
  111  * is read by a user process, etc.  However, that has its own problems.
  112  */
  113 
  114 /* Floating point definitions from <float.h>. */
  115 #define FLT_MANT_DIG    24              /* p */
  116 #define FLT_MAX_EXP     128             /* emax */
  117 
  118 /*
  119  * Internal accounting functions.
  120  * The former's operation is described in Leffler, et al., and the latter
  121  * was provided by UCB with the 4.4BSD-Lite release
  122  */
  123 static uint32_t encode_timeval(struct timeval);
  124 static uint32_t encode_long(long);
  125 static void     acctwatch(void);
  126 static void     acct_thread(void *);
  127 static int      acct_disable(struct thread *);
  128 
  129 /*
  130  * Accounting vnode pointer, saved vnode pointer, and flags for each.
  131  * acct_sx protects against changes to the active vnode and credentials
  132  * while accounting records are being committed to disk.
  133  */
  134 static int               acct_configured;
  135 static int               acct_suspended;
  136 static struct vnode     *acct_vp;
  137 static struct ucred     *acct_cred;
  138 static int               acct_flags;
  139 static struct sx         acct_sx;
  140 
  141 SX_SYSINIT(acct, &acct_sx, "acct_sx");
  142 
  143 /*
  144  * State of the accounting kthread.
  145  */
  146 static int               acct_state;
  147 
  148 #define ACCT_RUNNING    1       /* Accounting kthread is running. */
  149 #define ACCT_EXITREQ    2       /* Accounting kthread should exit. */
  150 
  151 /*
  152  * Values associated with enabling and disabling accounting
  153  */
  154 static int acctsuspend = 2;     /* stop accounting when < 2% free space left */
  155 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
  156         &acctsuspend, 0, "percentage of free disk space below which accounting stops");
  157 
  158 static int acctresume = 4;      /* resume when free space risen to > 4% */
  159 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
  160         &acctresume, 0, "percentage of free disk space above which accounting resumes");
  161 
  162 static int acctchkfreq = 15;    /* frequency (in seconds) to check space */
  163 
  164 static int
  165 sysctl_acct_chkfreq(SYSCTL_HANDLER_ARGS)
  166 {
  167         int error, value;
  168 
  169         /* Write out the old value. */
  170         error = SYSCTL_OUT(req, &acctchkfreq, sizeof(int));
  171         if (error || req->newptr == NULL)
  172                 return (error);
  173 
  174         /* Read in and verify the new value. */
  175         error = SYSCTL_IN(req, &value, sizeof(int));
  176         if (error)
  177                 return (error);
  178         if (value <= 0)
  179                 return (EINVAL);
  180         acctchkfreq = value;
  181         return (0);
  182 }
  183 SYSCTL_PROC(_kern, OID_AUTO, acct_chkfreq, CTLTYPE_INT|CTLFLAG_RW,
  184     &acctchkfreq, 0, sysctl_acct_chkfreq, "I",
  185     "frequency for checking the free space");
  186 
  187 SYSCTL_INT(_kern, OID_AUTO, acct_configured, CTLFLAG_RD, &acct_configured, 0,
  188         "Accounting configured or not");
  189 
  190 SYSCTL_INT(_kern, OID_AUTO, acct_suspended, CTLFLAG_RD, &acct_suspended, 0,
  191         "Accounting suspended or not");
  192 
  193 /*
  194  * Accounting system call.  Written based on the specification and previous
  195  * implementation done by Mark Tinguely.
  196  */
  197 int
  198 acct(struct thread *td, struct acct_args *uap)
  199 {
  200         struct nameidata nd;
  201         int error, flags, vfslocked;
  202 
  203         error = priv_check(td, PRIV_ACCT);
  204         if (error)
  205                 return (error);
  206 
  207         /*
  208          * If accounting is to be started to a file, open that file for
  209          * appending and make sure it's a 'normal'.
  210          */
  211         if (uap->path != NULL) {
  212                 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE | AUDITVNODE1,
  213                     UIO_USERSPACE, uap->path, td);
  214                 flags = FWRITE | O_APPEND;
  215                 error = vn_open(&nd, &flags, 0, NULL);
  216                 if (error)
  217                         return (error);
  218                 vfslocked = NDHASGIANT(&nd);
  219                 NDFREE(&nd, NDF_ONLY_PNBUF);
  220 #ifdef MAC
  221                 error = mac_check_system_acct(td->td_ucred, nd.ni_vp);
  222                 if (error) {
  223                         VOP_UNLOCK(nd.ni_vp, 0, td);
  224                         vn_close(nd.ni_vp, flags, td->td_ucred, td);
  225                         VFS_UNLOCK_GIANT(vfslocked);
  226                         return (error);
  227                 }
  228 #endif
  229                 VOP_UNLOCK(nd.ni_vp, 0, td);
  230                 if (nd.ni_vp->v_type != VREG) {
  231                         vn_close(nd.ni_vp, flags, td->td_ucred, td);
  232                         VFS_UNLOCK_GIANT(vfslocked);
  233                         return (EACCES);
  234                 }
  235                 VFS_UNLOCK_GIANT(vfslocked);
  236 #ifdef MAC
  237         } else {
  238                 error = mac_check_system_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          * If accounting was previously enabled, kill the old space-watcher,
  252          * close the file, and (if no new file was specified, leave).  Reset
  253          * the suspended state regardless of whether accounting remains
  254          * enabled.
  255          */
  256         acct_suspended = 0;
  257         if (acct_vp != NULL) {
  258                 vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
  259                 error = acct_disable(td);
  260                 VFS_UNLOCK_GIANT(vfslocked);
  261         }
  262         if (uap->path == NULL) {
  263                 if (acct_state & ACCT_RUNNING) {
  264                         acct_state |= ACCT_EXITREQ;
  265                         wakeup(&acct_state);
  266                 }
  267                 sx_xunlock(&acct_sx);
  268                 return (error);
  269         }
  270 
  271         /*
  272          * Save the new accounting file vnode, and schedule the new
  273          * free space watcher.
  274          */
  275         acct_vp = nd.ni_vp;
  276         acct_cred = crhold(td->td_ucred);
  277         acct_flags = flags;
  278         if (acct_state & ACCT_RUNNING)
  279                 acct_state &= ~ACCT_EXITREQ;
  280         else {
  281                 /*
  282                  * Try to start up an accounting kthread.  We may start more
  283                  * than one, but if so the extras will commit suicide as
  284                  * soon as they start up.
  285                  */
  286                 error = kthread_create(acct_thread, NULL, NULL, 0, 0,
  287                     "accounting");
  288                 if (error) {
  289                         vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
  290                         (void) vn_close(acct_vp, acct_flags, acct_cred, td);
  291                         VFS_UNLOCK_GIANT(vfslocked);
  292                         crfree(acct_cred);
  293                         acct_configured = 0;
  294                         acct_vp = NULL;
  295                         acct_cred = NULL;
  296                         acct_flags = 0;
  297                         sx_xunlock(&acct_sx);
  298                         log(LOG_NOTICE, "Unable to start accounting thread\n");
  299                         return (error);
  300                 }
  301         }
  302         acct_configured = 1;
  303         sx_xunlock(&acct_sx);
  304         log(LOG_NOTICE, "Accounting enabled\n");
  305         return (error);
  306 }
  307 
  308 /*
  309  * Disable currently in-progress accounting by closing the vnode, dropping
  310  * our reference to the credential, and clearing the vnode's flags.
  311  */
  312 static int
  313 acct_disable(struct thread *td)
  314 {
  315         int error;
  316 
  317         sx_assert(&acct_sx, SX_XLOCKED);
  318         error = vn_close(acct_vp, acct_flags, acct_cred, td);
  319         crfree(acct_cred);
  320         acct_configured = 0;
  321         acct_vp = NULL;
  322         acct_cred = NULL;
  323         acct_flags = 0;
  324         log(LOG_NOTICE, "Accounting disabled\n");
  325         return (error);
  326 }
  327 
  328 /*
  329  * Write out process accounting information, on process exit.
  330  * Data to be written out is specified in Leffler, et al.
  331  * and are enumerated below.  (They're also noted in the system
  332  * "acct.h" header file.)
  333  */
  334 int
  335 acct_process(struct thread *td)
  336 {
  337         struct acctv2 acct;
  338         struct timeval ut, st, tmp;
  339         struct plimit *newlim, *oldlim;
  340         struct proc *p;
  341         struct rusage ru;
  342         int t, ret, vfslocked;
  343 
  344         /*
  345          * Lockless check of accounting condition before doing the hard
  346          * work.
  347          */
  348         if (acct_vp == NULL || acct_suspended)
  349                 return (0);
  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 
  365         /*
  366          * Get process accounting information.
  367          */
  368 
  369         PROC_LOCK(p);
  370         /* (1) The name of the command that ran */
  371         bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
  372 
  373         /* (2) The amount of user and system time that was used */
  374         rufetchcalc(p, &ru, &ut, &st);
  375         acct.ac_utime = encode_timeval(ut);
  376         acct.ac_stime = encode_timeval(st);
  377 
  378         /* (3) The elapsed time the command ran (and its starting time) */
  379         tmp = boottime;
  380         timevaladd(&tmp, &p->p_stats->p_start);
  381         acct.ac_btime = tmp.tv_sec;
  382         microuptime(&tmp);
  383         timevalsub(&tmp, &p->p_stats->p_start);
  384         acct.ac_etime = encode_timeval(tmp);
  385 
  386         /* (4) The average amount of memory used */
  387         tmp = ut;
  388         timevaladd(&tmp, &st);
  389         /* Convert tmp (i.e. u + s) into hz units to match ru_i*. */
  390         t = tmp.tv_sec * hz + tmp.tv_usec / tick;
  391         if (t)
  392                 acct.ac_mem = encode_long((ru.ru_ixrss + ru.ru_idrss +
  393                     + ru.ru_isrss) / t);
  394         else
  395                 acct.ac_mem = 0;
  396 
  397         /* (5) The number of disk I/O operations done */
  398         acct.ac_io = encode_long(ru.ru_inblock + ru.ru_oublock);
  399 
  400         /* (6) The UID and GID of the process */
  401         acct.ac_uid = p->p_ucred->cr_ruid;
  402         acct.ac_gid = p->p_ucred->cr_rgid;
  403 
  404         /* (7) The terminal from which the process was started */
  405         SESS_LOCK(p->p_session);
  406         if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
  407                 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev);
  408         else
  409                 acct.ac_tty = NODEV;
  410         SESS_UNLOCK(p->p_session);
  411 
  412         /* (8) The boolean flags that tell how the process terminated, etc. */
  413         acct.ac_flagx = p->p_acflag;
  414         PROC_UNLOCK(p);
  415 
  416         /* Setup ancillary structure fields. */
  417         acct.ac_flagx |= ANVER;
  418         acct.ac_zero = 0;
  419         acct.ac_version = 2;
  420         acct.ac_len = acct.ac_len2 = sizeof(acct);
  421 
  422         /*
  423          * Eliminate any file size rlimit.
  424          */
  425         newlim = lim_alloc();
  426         PROC_LOCK(p);
  427         oldlim = p->p_limit;
  428         lim_copy(newlim, oldlim);
  429         newlim->pl_rlimit[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
  430         p->p_limit = newlim;
  431         PROC_UNLOCK(p);
  432         lim_free(oldlim);
  433 
  434         /*
  435          * Write the accounting information to the file.
  436          */
  437         vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
  438         VOP_LEASE(acct_vp, td, acct_cred, LEASE_WRITE);
  439         ret = vn_rdwr(UIO_WRITE, acct_vp, (caddr_t)&acct, sizeof (acct),
  440             (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, acct_cred, NOCRED,
  441             (int *)0, td);
  442         VFS_UNLOCK_GIANT(vfslocked);
  443         sx_sunlock(&acct_sx);
  444         return (ret);
  445 }
  446 
  447 /* FLOAT_CONVERSION_START (Regression testing; don't remove this line.) */
  448 
  449 /* Convert timevals and longs into IEEE-754 bit patterns. */
  450 
  451 /* Mantissa mask (MSB is implied, so subtract 1). */
  452 #define MANT_MASK ((1 << (FLT_MANT_DIG - 1)) - 1)
  453 
  454 /*
  455  * We calculate integer values to a precision of approximately
  456  * 28 bits.
  457  * This is high-enough precision to fill the 24 float bits
  458  * and low-enough to avoid overflowing the 32 int bits.
  459  */
  460 #define CALC_BITS 28
  461 
  462 /* log_2(1000000). */
  463 #define LOG2_1M 20
  464 
  465 /*
  466  * Convert the elements of a timeval into a 32-bit word holding
  467  * the bits of a IEEE-754 float.
  468  * The float value represents the timeval's value in microsecond units.
  469  */
  470 static uint32_t
  471 encode_timeval(struct timeval tv)
  472 {
  473         int log2_s;
  474         int val, exp;   /* Unnormalized value and exponent */
  475         int norm_exp;   /* Normalized exponent */
  476         int shift;
  477 
  478         /*
  479          * First calculate value and exponent to about CALC_BITS precision.
  480          * Note that the following conditionals have been ordered so that
  481          * the most common cases appear first.
  482          */
  483         if (tv.tv_sec == 0) {
  484                 if (tv.tv_usec == 0)
  485                         return (0);
  486                 exp = 0;
  487                 val = tv.tv_usec;
  488         } else {
  489                 /*
  490                  * Calculate the value to a precision of approximately
  491                  * CALC_BITS.
  492                  */
  493                 log2_s = fls(tv.tv_sec) - 1;
  494                 if (log2_s + LOG2_1M < CALC_BITS) {
  495                         exp = 0;
  496                         val = 1000000 * tv.tv_sec + tv.tv_usec;
  497                 } else {
  498                         exp = log2_s + LOG2_1M - CALC_BITS;
  499                         val = (unsigned int)(((u_int64_t)1000000 * tv.tv_sec +
  500                             tv.tv_usec) >> exp);
  501                 }
  502         }
  503         /* Now normalize and pack the value into an IEEE-754 float. */
  504         norm_exp = fls(val) - 1;
  505         shift = FLT_MANT_DIG - norm_exp - 1;
  506 #ifdef ACCT_DEBUG
  507         printf("val=%d exp=%d shift=%d log2(val)=%d\n",
  508             val, exp, shift, norm_exp);
  509         printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp,
  510             ((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK));
  511 #endif
  512         return (((FLT_MAX_EXP - 1 + exp + norm_exp) << (FLT_MANT_DIG - 1)) |
  513             ((shift > 0 ? val << shift : val >> -shift) & MANT_MASK));
  514 }
  515 
  516 /*
  517  * Convert a non-negative long value into the bit pattern of
  518  * an IEEE-754 float value.
  519  */
  520 static uint32_t
  521 encode_long(long val)
  522 {
  523         int norm_exp;   /* Normalized exponent */
  524         int shift;
  525 
  526         if (val == 0)
  527                 return (0);
  528         if (val < 0) {
  529                 log(LOG_NOTICE,
  530                     "encode_long: negative value %ld in accounting record\n",
  531                     val);
  532                 val = LONG_MAX;
  533         }
  534         norm_exp = fls(val) - 1;
  535         shift = FLT_MANT_DIG - norm_exp - 1;
  536 #ifdef ACCT_DEBUG
  537         printf("val=%d shift=%d log2(val)=%d\n",
  538             val, shift, norm_exp);
  539         printf("exp=%x mant=%x\n", FLT_MAX_EXP - 1 + exp + norm_exp,
  540             ((shift > 0 ? (val << shift) : (val >> -shift)) & MANT_MASK));
  541 #endif
  542         return (((FLT_MAX_EXP - 1 + norm_exp) << (FLT_MANT_DIG - 1)) |
  543             ((shift > 0 ? val << shift : val >> -shift) & MANT_MASK));
  544 }
  545 
  546 /* FLOAT_CONVERSION_END (Regression testing; don't remove this line.) */
  547 
  548 /*
  549  * Periodically check the filesystem to see if accounting
  550  * should be turned on or off.  Beware the case where the vnode
  551  * has been vgone()'d out from underneath us, e.g. when the file
  552  * system containing the accounting file has been forcibly unmounted.
  553  */
  554 /* ARGSUSED */
  555 static void
  556 acctwatch(void)
  557 {
  558         struct statfs sb;
  559         int vfslocked;
  560 
  561         sx_assert(&acct_sx, SX_XLOCKED);
  562 
  563         /*
  564          * If accounting was disabled before our kthread was scheduled,
  565          * then acct_vp might be NULL.  If so, just ask our kthread to
  566          * exit and return.
  567          */
  568         if (acct_vp == NULL) {
  569                 acct_state |= ACCT_EXITREQ;
  570                 return;
  571         }
  572 
  573         /*
  574          * If our vnode is no longer valid, tear it down and signal the
  575          * accounting thread to die.
  576          */
  577         vfslocked = VFS_LOCK_GIANT(acct_vp->v_mount);
  578         if (acct_vp->v_type == VBAD) {
  579                 (void) acct_disable(NULL);
  580                 VFS_UNLOCK_GIANT(vfslocked);
  581                 acct_state |= ACCT_EXITREQ;
  582                 return;
  583         }
  584 
  585         /*
  586          * Stopping here is better than continuing, maybe it will be VBAD
  587          * next time around.
  588          */
  589         if (VFS_STATFS(acct_vp->v_mount, &sb, curthread) < 0) {
  590                 VFS_UNLOCK_GIANT(vfslocked);
  591                 return;
  592         }
  593         VFS_UNLOCK_GIANT(vfslocked);
  594         if (acct_suspended) {
  595                 if (sb.f_bavail > (int64_t)(acctresume * sb.f_blocks /
  596                     100)) {
  597                         acct_suspended = 0;
  598                         log(LOG_NOTICE, "Accounting resumed\n");
  599                 }
  600         } else {
  601                 if (sb.f_bavail <= (int64_t)(acctsuspend * sb.f_blocks /
  602                     100)) {
  603                         acct_suspended = 1;
  604                         log(LOG_NOTICE, "Accounting suspended\n");
  605                 }
  606         }
  607 }
  608 
  609 /*
  610  * The main loop for the dedicated kernel thread that periodically calls
  611  * acctwatch().
  612  */
  613 static void
  614 acct_thread(void *dummy)
  615 {
  616         u_char pri;
  617 
  618         /* This is a low-priority kernel thread. */
  619         pri = PRI_MAX_KERN;
  620         thread_lock(curthread);
  621         sched_prio(curthread, pri);
  622         thread_unlock(curthread);
  623 
  624         /* If another accounting kthread is already running, just die. */
  625         sx_xlock(&acct_sx);
  626         if (acct_state & ACCT_RUNNING) {
  627                 sx_xunlock(&acct_sx);
  628                 kthread_exit(0);
  629         }
  630         acct_state |= ACCT_RUNNING;
  631 
  632         /* Loop until we are asked to exit. */
  633         while (!(acct_state & ACCT_EXITREQ)) {
  634 
  635                 /* Perform our periodic checks. */
  636                 acctwatch();
  637 
  638                 /*
  639                  * We check this flag again before sleeping since the
  640                  * acctwatch() might have shut down accounting and asked us
  641                  * to exit.
  642                  */
  643                 if (!(acct_state & ACCT_EXITREQ)) {
  644                         sx_sleep(&acct_state, &acct_sx, 0, "-",
  645                             acctchkfreq * hz);
  646                 }
  647         }
  648 
  649         /*
  650          * Acknowledge the exit request and shutdown.  We clear both the
  651          * exit request and running flags.
  652          */
  653         acct_state = 0;
  654         sx_xunlock(&acct_sx);
  655         kthread_exit(0);
  656 }

Cache object: 848c5b36aa3ffddb8e5bac6589fbac45


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.