The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_resource.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1982, 1986, 1991, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  * (c) UNIX System Laboratories, Inc.
    7  * All or some portions of this file are derived from material licensed
    8  * to the University of California by American Telephone and Telegraph
    9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   10  * the permission of UNIX System Laboratories, Inc.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  * 3. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      @(#)kern_resource.c     8.5 (Berkeley) 1/21/94
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD: releng/12.0/sys/kern/kern_resource.c 339187 2018-10-05 05:50:56Z mmacy $");
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/sysproto.h>
   45 #include <sys/file.h>
   46 #include <sys/kernel.h>
   47 #include <sys/lock.h>
   48 #include <sys/malloc.h>
   49 #include <sys/mutex.h>
   50 #include <sys/priv.h>
   51 #include <sys/proc.h>
   52 #include <sys/refcount.h>
   53 #include <sys/racct.h>
   54 #include <sys/resourcevar.h>
   55 #include <sys/rwlock.h>
   56 #include <sys/sched.h>
   57 #include <sys/sx.h>
   58 #include <sys/syscallsubr.h>
   59 #include <sys/sysctl.h>
   60 #include <sys/sysent.h>
   61 #include <sys/time.h>
   62 #include <sys/umtx.h>
   63 
   64 #include <vm/vm.h>
   65 #include <vm/vm_param.h>
   66 #include <vm/pmap.h>
   67 #include <vm/vm_map.h>
   68 
   69 
   70 static MALLOC_DEFINE(M_PLIMIT, "plimit", "plimit structures");
   71 static MALLOC_DEFINE(M_UIDINFO, "uidinfo", "uidinfo structures");
   72 #define UIHASH(uid)     (&uihashtbl[(uid) & uihash])
   73 static struct rwlock uihashtbl_lock;
   74 static LIST_HEAD(uihashhead, uidinfo) *uihashtbl;
   75 static u_long uihash;           /* size of hash table - 1 */
   76 
   77 static void     calcru1(struct proc *p, struct rusage_ext *ruxp,
   78                     struct timeval *up, struct timeval *sp);
   79 static int      donice(struct thread *td, struct proc *chgp, int n);
   80 static struct uidinfo *uilookup(uid_t uid);
   81 static void     ruxagg_locked(struct rusage_ext *rux, struct thread *td);
   82 
   83 /*
   84  * Resource controls and accounting.
   85  */
   86 #ifndef _SYS_SYSPROTO_H_
   87 struct getpriority_args {
   88         int     which;
   89         int     who;
   90 };
   91 #endif
   92 int
   93 sys_getpriority(struct thread *td, struct getpriority_args *uap)
   94 {
   95         struct proc *p;
   96         struct pgrp *pg;
   97         int error, low;
   98 
   99         error = 0;
  100         low = PRIO_MAX + 1;
  101         switch (uap->which) {
  102 
  103         case PRIO_PROCESS:
  104                 if (uap->who == 0)
  105                         low = td->td_proc->p_nice;
  106                 else {
  107                         p = pfind(uap->who);
  108                         if (p == NULL)
  109                                 break;
  110                         if (p_cansee(td, p) == 0)
  111                                 low = p->p_nice;
  112                         PROC_UNLOCK(p);
  113                 }
  114                 break;
  115 
  116         case PRIO_PGRP:
  117                 sx_slock(&proctree_lock);
  118                 if (uap->who == 0) {
  119                         pg = td->td_proc->p_pgrp;
  120                         PGRP_LOCK(pg);
  121                 } else {
  122                         pg = pgfind(uap->who);
  123                         if (pg == NULL) {
  124                                 sx_sunlock(&proctree_lock);
  125                                 break;
  126                         }
  127                 }
  128                 sx_sunlock(&proctree_lock);
  129                 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
  130                         PROC_LOCK(p);
  131                         if (p->p_state == PRS_NORMAL &&
  132                             p_cansee(td, p) == 0) {
  133                                 if (p->p_nice < low)
  134                                         low = p->p_nice;
  135                         }
  136                         PROC_UNLOCK(p);
  137                 }
  138                 PGRP_UNLOCK(pg);
  139                 break;
  140 
  141         case PRIO_USER:
  142                 if (uap->who == 0)
  143                         uap->who = td->td_ucred->cr_uid;
  144                 sx_slock(&allproc_lock);
  145                 FOREACH_PROC_IN_SYSTEM(p) {
  146                         PROC_LOCK(p);
  147                         if (p->p_state == PRS_NORMAL &&
  148                             p_cansee(td, p) == 0 &&
  149                             p->p_ucred->cr_uid == uap->who) {
  150                                 if (p->p_nice < low)
  151                                         low = p->p_nice;
  152                         }
  153                         PROC_UNLOCK(p);
  154                 }
  155                 sx_sunlock(&allproc_lock);
  156                 break;
  157 
  158         default:
  159                 error = EINVAL;
  160                 break;
  161         }
  162         if (low == PRIO_MAX + 1 && error == 0)
  163                 error = ESRCH;
  164         td->td_retval[0] = low;
  165         return (error);
  166 }
  167 
  168 #ifndef _SYS_SYSPROTO_H_
  169 struct setpriority_args {
  170         int     which;
  171         int     who;
  172         int     prio;
  173 };
  174 #endif
  175 int
  176 sys_setpriority(struct thread *td, struct setpriority_args *uap)
  177 {
  178         struct proc *curp, *p;
  179         struct pgrp *pg;
  180         int found = 0, error = 0;
  181 
  182         curp = td->td_proc;
  183         switch (uap->which) {
  184         case PRIO_PROCESS:
  185                 if (uap->who == 0) {
  186                         PROC_LOCK(curp);
  187                         error = donice(td, curp, uap->prio);
  188                         PROC_UNLOCK(curp);
  189                 } else {
  190                         p = pfind(uap->who);
  191                         if (p == NULL)
  192                                 break;
  193                         error = p_cansee(td, p);
  194                         if (error == 0)
  195                                 error = donice(td, p, uap->prio);
  196                         PROC_UNLOCK(p);
  197                 }
  198                 found++;
  199                 break;
  200 
  201         case PRIO_PGRP:
  202                 sx_slock(&proctree_lock);
  203                 if (uap->who == 0) {
  204                         pg = curp->p_pgrp;
  205                         PGRP_LOCK(pg);
  206                 } else {
  207                         pg = pgfind(uap->who);
  208                         if (pg == NULL) {
  209                                 sx_sunlock(&proctree_lock);
  210                                 break;
  211                         }
  212                 }
  213                 sx_sunlock(&proctree_lock);
  214                 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
  215                         PROC_LOCK(p);
  216                         if (p->p_state == PRS_NORMAL &&
  217                             p_cansee(td, p) == 0) {
  218                                 error = donice(td, p, uap->prio);
  219                                 found++;
  220                         }
  221                         PROC_UNLOCK(p);
  222                 }
  223                 PGRP_UNLOCK(pg);
  224                 break;
  225 
  226         case PRIO_USER:
  227                 if (uap->who == 0)
  228                         uap->who = td->td_ucred->cr_uid;
  229                 sx_slock(&allproc_lock);
  230                 FOREACH_PROC_IN_SYSTEM(p) {
  231                         PROC_LOCK(p);
  232                         if (p->p_state == PRS_NORMAL &&
  233                             p->p_ucred->cr_uid == uap->who &&
  234                             p_cansee(td, p) == 0) {
  235                                 error = donice(td, p, uap->prio);
  236                                 found++;
  237                         }
  238                         PROC_UNLOCK(p);
  239                 }
  240                 sx_sunlock(&allproc_lock);
  241                 break;
  242 
  243         default:
  244                 error = EINVAL;
  245                 break;
  246         }
  247         if (found == 0 && error == 0)
  248                 error = ESRCH;
  249         return (error);
  250 }
  251 
  252 /*
  253  * Set "nice" for a (whole) process.
  254  */
  255 static int
  256 donice(struct thread *td, struct proc *p, int n)
  257 {
  258         int error;
  259 
  260         PROC_LOCK_ASSERT(p, MA_OWNED);
  261         if ((error = p_cansched(td, p)))
  262                 return (error);
  263         if (n > PRIO_MAX)
  264                 n = PRIO_MAX;
  265         if (n < PRIO_MIN)
  266                 n = PRIO_MIN;
  267         if (n < p->p_nice && priv_check(td, PRIV_SCHED_SETPRIORITY) != 0)
  268                 return (EACCES);
  269         sched_nice(p, n);
  270         return (0);
  271 }
  272 
  273 static int unprivileged_idprio;
  274 SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_idprio, CTLFLAG_RW,
  275     &unprivileged_idprio, 0, "Allow non-root users to set an idle priority");
  276 
  277 /*
  278  * Set realtime priority for LWP.
  279  */
  280 #ifndef _SYS_SYSPROTO_H_
  281 struct rtprio_thread_args {
  282         int             function;
  283         lwpid_t         lwpid;
  284         struct rtprio   *rtp;
  285 };
  286 #endif
  287 int
  288 sys_rtprio_thread(struct thread *td, struct rtprio_thread_args *uap)
  289 {
  290         struct proc *p;
  291         struct rtprio rtp;
  292         struct thread *td1;
  293         int cierror, error;
  294 
  295         /* Perform copyin before acquiring locks if needed. */
  296         if (uap->function == RTP_SET)
  297                 cierror = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
  298         else
  299                 cierror = 0;
  300 
  301         if (uap->lwpid == 0 || uap->lwpid == td->td_tid) {
  302                 p = td->td_proc;
  303                 td1 = td;
  304                 PROC_LOCK(p);
  305         } else {
  306                 /* Only look up thread in current process */
  307                 td1 = tdfind(uap->lwpid, curproc->p_pid);
  308                 if (td1 == NULL)
  309                         return (ESRCH);
  310                 p = td1->td_proc;
  311         }
  312 
  313         switch (uap->function) {
  314         case RTP_LOOKUP:
  315                 if ((error = p_cansee(td, p)))
  316                         break;
  317                 pri_to_rtp(td1, &rtp);
  318                 PROC_UNLOCK(p);
  319                 return (copyout(&rtp, uap->rtp, sizeof(struct rtprio)));
  320         case RTP_SET:
  321                 if ((error = p_cansched(td, p)) || (error = cierror))
  322                         break;
  323 
  324                 /* Disallow setting rtprio in most cases if not superuser. */
  325 
  326                 /*
  327                  * Realtime priority has to be restricted for reasons which
  328                  * should be obvious.  However, for idleprio processes, there is
  329                  * a potential for system deadlock if an idleprio process gains
  330                  * a lock on a resource that other processes need (and the
  331                  * idleprio process can't run due to a CPU-bound normal
  332                  * process).  Fix me!  XXX
  333                  *
  334                  * This problem is not only related to idleprio process.
  335                  * A user level program can obtain a file lock and hold it
  336                  * indefinitely.  Additionally, without idleprio processes it is
  337                  * still conceivable that a program with low priority will never
  338                  * get to run.  In short, allowing this feature might make it
  339                  * easier to lock a resource indefinitely, but it is not the
  340                  * only thing that makes it possible.
  341                  */
  342                 if (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_REALTIME ||
  343                     (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_IDLE &&
  344                     unprivileged_idprio == 0)) {
  345                         error = priv_check(td, PRIV_SCHED_RTPRIO);
  346                         if (error)
  347                                 break;
  348                 }
  349                 error = rtp_to_pri(&rtp, td1);
  350                 break;
  351         default:
  352                 error = EINVAL;
  353                 break;
  354         }
  355         PROC_UNLOCK(p);
  356         return (error);
  357 }
  358 
  359 /*
  360  * Set realtime priority.
  361  */
  362 #ifndef _SYS_SYSPROTO_H_
  363 struct rtprio_args {
  364         int             function;
  365         pid_t           pid;
  366         struct rtprio   *rtp;
  367 };
  368 #endif
  369 int
  370 sys_rtprio(struct thread *td, struct rtprio_args *uap)
  371 {
  372         struct proc *p;
  373         struct thread *tdp;
  374         struct rtprio rtp;
  375         int cierror, error;
  376 
  377         /* Perform copyin before acquiring locks if needed. */
  378         if (uap->function == RTP_SET)
  379                 cierror = copyin(uap->rtp, &rtp, sizeof(struct rtprio));
  380         else
  381                 cierror = 0;
  382 
  383         if (uap->pid == 0) {
  384                 p = td->td_proc;
  385                 PROC_LOCK(p);
  386         } else {
  387                 p = pfind(uap->pid);
  388                 if (p == NULL)
  389                         return (ESRCH);
  390         }
  391 
  392         switch (uap->function) {
  393         case RTP_LOOKUP:
  394                 if ((error = p_cansee(td, p)))
  395                         break;
  396                 /*
  397                  * Return OUR priority if no pid specified,
  398                  * or if one is, report the highest priority
  399                  * in the process.  There isn't much more you can do as
  400                  * there is only room to return a single priority.
  401                  * Note: specifying our own pid is not the same
  402                  * as leaving it zero.
  403                  */
  404                 if (uap->pid == 0) {
  405                         pri_to_rtp(td, &rtp);
  406                 } else {
  407                         struct rtprio rtp2;
  408 
  409                         rtp.type = RTP_PRIO_IDLE;
  410                         rtp.prio = RTP_PRIO_MAX;
  411                         FOREACH_THREAD_IN_PROC(p, tdp) {
  412                                 pri_to_rtp(tdp, &rtp2);
  413                                 if (rtp2.type <  rtp.type ||
  414                                     (rtp2.type == rtp.type &&
  415                                     rtp2.prio < rtp.prio)) {
  416                                         rtp.type = rtp2.type;
  417                                         rtp.prio = rtp2.prio;
  418                                 }
  419                         }
  420                 }
  421                 PROC_UNLOCK(p);
  422                 return (copyout(&rtp, uap->rtp, sizeof(struct rtprio)));
  423         case RTP_SET:
  424                 if ((error = p_cansched(td, p)) || (error = cierror))
  425                         break;
  426 
  427                 /*
  428                  * Disallow setting rtprio in most cases if not superuser.
  429                  * See the comment in sys_rtprio_thread about idprio
  430                  * threads holding a lock.
  431                  */
  432                 if (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_REALTIME ||
  433                     (RTP_PRIO_BASE(rtp.type) == RTP_PRIO_IDLE &&
  434                     !unprivileged_idprio)) {
  435                         error = priv_check(td, PRIV_SCHED_RTPRIO);
  436                         if (error)
  437                                 break;
  438                 }
  439 
  440                 /*
  441                  * If we are setting our own priority, set just our
  442                  * thread but if we are doing another process,
  443                  * do all the threads on that process. If we
  444                  * specify our own pid we do the latter.
  445                  */
  446                 if (uap->pid == 0) {
  447                         error = rtp_to_pri(&rtp, td);
  448                 } else {
  449                         FOREACH_THREAD_IN_PROC(p, td) {
  450                                 if ((error = rtp_to_pri(&rtp, td)) != 0)
  451                                         break;
  452                         }
  453                 }
  454                 break;
  455         default:
  456                 error = EINVAL;
  457                 break;
  458         }
  459         PROC_UNLOCK(p);
  460         return (error);
  461 }
  462 
  463 int
  464 rtp_to_pri(struct rtprio *rtp, struct thread *td)
  465 {
  466         u_char  newpri, oldclass, oldpri;
  467 
  468         switch (RTP_PRIO_BASE(rtp->type)) {
  469         case RTP_PRIO_REALTIME:
  470                 if (rtp->prio > RTP_PRIO_MAX)
  471                         return (EINVAL);
  472                 newpri = PRI_MIN_REALTIME + rtp->prio;
  473                 break;
  474         case RTP_PRIO_NORMAL:
  475                 if (rtp->prio > (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE))
  476                         return (EINVAL);
  477                 newpri = PRI_MIN_TIMESHARE + rtp->prio;
  478                 break;
  479         case RTP_PRIO_IDLE:
  480                 if (rtp->prio > RTP_PRIO_MAX)
  481                         return (EINVAL);
  482                 newpri = PRI_MIN_IDLE + rtp->prio;
  483                 break;
  484         default:
  485                 return (EINVAL);
  486         }
  487 
  488         thread_lock(td);
  489         oldclass = td->td_pri_class;
  490         sched_class(td, rtp->type);     /* XXX fix */
  491         oldpri = td->td_user_pri;
  492         sched_user_prio(td, newpri);
  493         if (td->td_user_pri != oldpri && (oldclass != RTP_PRIO_NORMAL ||
  494             td->td_pri_class != RTP_PRIO_NORMAL))
  495                 sched_prio(td, td->td_user_pri);
  496         if (TD_ON_UPILOCK(td) && oldpri != newpri) {
  497                 critical_enter();
  498                 thread_unlock(td);
  499                 umtx_pi_adjust(td, oldpri);
  500                 critical_exit();
  501         } else
  502                 thread_unlock(td);
  503         return (0);
  504 }
  505 
  506 void
  507 pri_to_rtp(struct thread *td, struct rtprio *rtp)
  508 {
  509 
  510         thread_lock(td);
  511         switch (PRI_BASE(td->td_pri_class)) {
  512         case PRI_REALTIME:
  513                 rtp->prio = td->td_base_user_pri - PRI_MIN_REALTIME;
  514                 break;
  515         case PRI_TIMESHARE:
  516                 rtp->prio = td->td_base_user_pri - PRI_MIN_TIMESHARE;
  517                 break;
  518         case PRI_IDLE:
  519                 rtp->prio = td->td_base_user_pri - PRI_MIN_IDLE;
  520                 break;
  521         default:
  522                 break;
  523         }
  524         rtp->type = td->td_pri_class;
  525         thread_unlock(td);
  526 }
  527 
  528 #if defined(COMPAT_43)
  529 #ifndef _SYS_SYSPROTO_H_
  530 struct osetrlimit_args {
  531         u_int   which;
  532         struct  orlimit *rlp;
  533 };
  534 #endif
  535 int
  536 osetrlimit(struct thread *td, struct osetrlimit_args *uap)
  537 {
  538         struct orlimit olim;
  539         struct rlimit lim;
  540         int error;
  541 
  542         if ((error = copyin(uap->rlp, &olim, sizeof(struct orlimit))))
  543                 return (error);
  544         lim.rlim_cur = olim.rlim_cur;
  545         lim.rlim_max = olim.rlim_max;
  546         error = kern_setrlimit(td, uap->which, &lim);
  547         return (error);
  548 }
  549 
  550 #ifndef _SYS_SYSPROTO_H_
  551 struct ogetrlimit_args {
  552         u_int   which;
  553         struct  orlimit *rlp;
  554 };
  555 #endif
  556 int
  557 ogetrlimit(struct thread *td, struct ogetrlimit_args *uap)
  558 {
  559         struct orlimit olim;
  560         struct rlimit rl;
  561         int error;
  562 
  563         if (uap->which >= RLIM_NLIMITS)
  564                 return (EINVAL);
  565         lim_rlimit(td, uap->which, &rl);
  566 
  567         /*
  568          * XXX would be more correct to convert only RLIM_INFINITY to the
  569          * old RLIM_INFINITY and fail with EOVERFLOW for other larger
  570          * values.  Most 64->32 and 32->16 conversions, including not
  571          * unimportant ones of uids are even more broken than what we
  572          * do here (they blindly truncate).  We don't do this correctly
  573          * here since we have little experience with EOVERFLOW yet.
  574          * Elsewhere, getuid() can't fail...
  575          */
  576         olim.rlim_cur = rl.rlim_cur > 0x7fffffff ? 0x7fffffff : rl.rlim_cur;
  577         olim.rlim_max = rl.rlim_max > 0x7fffffff ? 0x7fffffff : rl.rlim_max;
  578         error = copyout(&olim, uap->rlp, sizeof(olim));
  579         return (error);
  580 }
  581 #endif /* COMPAT_43 */
  582 
  583 #ifndef _SYS_SYSPROTO_H_
  584 struct __setrlimit_args {
  585         u_int   which;
  586         struct  rlimit *rlp;
  587 };
  588 #endif
  589 int
  590 sys_setrlimit(struct thread *td, struct __setrlimit_args *uap)
  591 {
  592         struct rlimit alim;
  593         int error;
  594 
  595         if ((error = copyin(uap->rlp, &alim, sizeof(struct rlimit))))
  596                 return (error);
  597         error = kern_setrlimit(td, uap->which, &alim);
  598         return (error);
  599 }
  600 
  601 static void
  602 lim_cb(void *arg)
  603 {
  604         struct rlimit rlim;
  605         struct thread *td;
  606         struct proc *p;
  607 
  608         p = arg;
  609         PROC_LOCK_ASSERT(p, MA_OWNED);
  610         /*
  611          * Check if the process exceeds its cpu resource allocation.  If
  612          * it reaches the max, arrange to kill the process in ast().
  613          */
  614         if (p->p_cpulimit == RLIM_INFINITY)
  615                 return;
  616         PROC_STATLOCK(p);
  617         FOREACH_THREAD_IN_PROC(p, td) {
  618                 ruxagg(p, td);
  619         }
  620         PROC_STATUNLOCK(p);
  621         if (p->p_rux.rux_runtime > p->p_cpulimit * cpu_tickrate()) {
  622                 lim_rlimit_proc(p, RLIMIT_CPU, &rlim);
  623                 if (p->p_rux.rux_runtime >= rlim.rlim_max * cpu_tickrate()) {
  624                         killproc(p, "exceeded maximum CPU limit");
  625                 } else {
  626                         if (p->p_cpulimit < rlim.rlim_max)
  627                                 p->p_cpulimit += 5;
  628                         kern_psignal(p, SIGXCPU);
  629                 }
  630         }
  631         if ((p->p_flag & P_WEXIT) == 0)
  632                 callout_reset_sbt(&p->p_limco, SBT_1S, 0,
  633                     lim_cb, p, C_PREL(1));
  634 }
  635 
  636 int
  637 kern_setrlimit(struct thread *td, u_int which, struct rlimit *limp)
  638 {
  639 
  640         return (kern_proc_setrlimit(td, td->td_proc, which, limp));
  641 }
  642 
  643 int
  644 kern_proc_setrlimit(struct thread *td, struct proc *p, u_int which,
  645     struct rlimit *limp)
  646 {
  647         struct plimit *newlim, *oldlim;
  648         struct rlimit *alimp;
  649         struct rlimit oldssiz;
  650         int error;
  651 
  652         if (which >= RLIM_NLIMITS)
  653                 return (EINVAL);
  654 
  655         /*
  656          * Preserve historical bugs by treating negative limits as unsigned.
  657          */
  658         if (limp->rlim_cur < 0)
  659                 limp->rlim_cur = RLIM_INFINITY;
  660         if (limp->rlim_max < 0)
  661                 limp->rlim_max = RLIM_INFINITY;
  662 
  663         oldssiz.rlim_cur = 0;
  664         newlim = lim_alloc();
  665         PROC_LOCK(p);
  666         oldlim = p->p_limit;
  667         alimp = &oldlim->pl_rlimit[which];
  668         if (limp->rlim_cur > alimp->rlim_max ||
  669             limp->rlim_max > alimp->rlim_max)
  670                 if ((error = priv_check(td, PRIV_PROC_SETRLIMIT))) {
  671                         PROC_UNLOCK(p);
  672                         lim_free(newlim);
  673                         return (error);
  674                 }
  675         if (limp->rlim_cur > limp->rlim_max)
  676                 limp->rlim_cur = limp->rlim_max;
  677         lim_copy(newlim, oldlim);
  678         alimp = &newlim->pl_rlimit[which];
  679 
  680         switch (which) {
  681 
  682         case RLIMIT_CPU:
  683                 if (limp->rlim_cur != RLIM_INFINITY &&
  684                     p->p_cpulimit == RLIM_INFINITY)
  685                         callout_reset_sbt(&p->p_limco, SBT_1S, 0,
  686                             lim_cb, p, C_PREL(1));
  687                 p->p_cpulimit = limp->rlim_cur;
  688                 break;
  689         case RLIMIT_DATA:
  690                 if (limp->rlim_cur > maxdsiz)
  691                         limp->rlim_cur = maxdsiz;
  692                 if (limp->rlim_max > maxdsiz)
  693                         limp->rlim_max = maxdsiz;
  694                 break;
  695 
  696         case RLIMIT_STACK:
  697                 if (limp->rlim_cur > maxssiz)
  698                         limp->rlim_cur = maxssiz;
  699                 if (limp->rlim_max > maxssiz)
  700                         limp->rlim_max = maxssiz;
  701                 oldssiz = *alimp;
  702                 if (p->p_sysent->sv_fixlimit != NULL)
  703                         p->p_sysent->sv_fixlimit(&oldssiz,
  704                             RLIMIT_STACK);
  705                 break;
  706 
  707         case RLIMIT_NOFILE:
  708                 if (limp->rlim_cur > maxfilesperproc)
  709                         limp->rlim_cur = maxfilesperproc;
  710                 if (limp->rlim_max > maxfilesperproc)
  711                         limp->rlim_max = maxfilesperproc;
  712                 break;
  713 
  714         case RLIMIT_NPROC:
  715                 if (limp->rlim_cur > maxprocperuid)
  716                         limp->rlim_cur = maxprocperuid;
  717                 if (limp->rlim_max > maxprocperuid)
  718                         limp->rlim_max = maxprocperuid;
  719                 if (limp->rlim_cur < 1)
  720                         limp->rlim_cur = 1;
  721                 if (limp->rlim_max < 1)
  722                         limp->rlim_max = 1;
  723                 break;
  724         }
  725         if (p->p_sysent->sv_fixlimit != NULL)
  726                 p->p_sysent->sv_fixlimit(limp, which);
  727         *alimp = *limp;
  728         p->p_limit = newlim;
  729         PROC_UPDATE_COW(p);
  730         PROC_UNLOCK(p);
  731         lim_free(oldlim);
  732 
  733         if (which == RLIMIT_STACK &&
  734             /*
  735              * Skip calls from exec_new_vmspace(), done when stack is
  736              * not mapped yet.
  737              */
  738             (td != curthread || (p->p_flag & P_INEXEC) == 0)) {
  739                 /*
  740                  * Stack is allocated to the max at exec time with only
  741                  * "rlim_cur" bytes accessible.  If stack limit is going
  742                  * up make more accessible, if going down make inaccessible.
  743                  */
  744                 if (limp->rlim_cur != oldssiz.rlim_cur) {
  745                         vm_offset_t addr;
  746                         vm_size_t size;
  747                         vm_prot_t prot;
  748 
  749                         if (limp->rlim_cur > oldssiz.rlim_cur) {
  750                                 prot = p->p_sysent->sv_stackprot;
  751                                 size = limp->rlim_cur - oldssiz.rlim_cur;
  752                                 addr = p->p_sysent->sv_usrstack -
  753                                     limp->rlim_cur;
  754                         } else {
  755                                 prot = VM_PROT_NONE;
  756                                 size = oldssiz.rlim_cur - limp->rlim_cur;
  757                                 addr = p->p_sysent->sv_usrstack -
  758                                     oldssiz.rlim_cur;
  759                         }
  760                         addr = trunc_page(addr);
  761                         size = round_page(size);
  762                         (void)vm_map_protect(&p->p_vmspace->vm_map,
  763                             addr, addr + size, prot, FALSE);
  764                 }
  765         }
  766 
  767         return (0);
  768 }
  769 
  770 #ifndef _SYS_SYSPROTO_H_
  771 struct __getrlimit_args {
  772         u_int   which;
  773         struct  rlimit *rlp;
  774 };
  775 #endif
  776 /* ARGSUSED */
  777 int
  778 sys_getrlimit(struct thread *td, struct __getrlimit_args *uap)
  779 {
  780         struct rlimit rlim;
  781         int error;
  782 
  783         if (uap->which >= RLIM_NLIMITS)
  784                 return (EINVAL);
  785         lim_rlimit(td, uap->which, &rlim);
  786         error = copyout(&rlim, uap->rlp, sizeof(struct rlimit));
  787         return (error);
  788 }
  789 
  790 /*
  791  * Transform the running time and tick information for children of proc p
  792  * into user and system time usage.
  793  */
  794 void
  795 calccru(struct proc *p, struct timeval *up, struct timeval *sp)
  796 {
  797 
  798         PROC_LOCK_ASSERT(p, MA_OWNED);
  799         calcru1(p, &p->p_crux, up, sp);
  800 }
  801 
  802 /*
  803  * Transform the running time and tick information in proc p into user
  804  * and system time usage.  If appropriate, include the current time slice
  805  * on this CPU.
  806  */
  807 void
  808 calcru(struct proc *p, struct timeval *up, struct timeval *sp)
  809 {
  810         struct thread *td;
  811         uint64_t runtime, u;
  812 
  813         PROC_LOCK_ASSERT(p, MA_OWNED);
  814         PROC_STATLOCK_ASSERT(p, MA_OWNED);
  815         /*
  816          * If we are getting stats for the current process, then add in the
  817          * stats that this thread has accumulated in its current time slice.
  818          * We reset the thread and CPU state as if we had performed a context
  819          * switch right here.
  820          */
  821         td = curthread;
  822         if (td->td_proc == p) {
  823                 u = cpu_ticks();
  824                 runtime = u - PCPU_GET(switchtime);
  825                 td->td_runtime += runtime;
  826                 td->td_incruntime += runtime;
  827                 PCPU_SET(switchtime, u);
  828         }
  829         /* Make sure the per-thread stats are current. */
  830         FOREACH_THREAD_IN_PROC(p, td) {
  831                 if (td->td_incruntime == 0)
  832                         continue;
  833                 ruxagg(p, td);
  834         }
  835         calcru1(p, &p->p_rux, up, sp);
  836 }
  837 
  838 /* Collect resource usage for a single thread. */
  839 void
  840 rufetchtd(struct thread *td, struct rusage *ru)
  841 {
  842         struct proc *p;
  843         uint64_t runtime, u;
  844 
  845         p = td->td_proc;
  846         PROC_STATLOCK_ASSERT(p, MA_OWNED);
  847         THREAD_LOCK_ASSERT(td, MA_OWNED);
  848         /*
  849          * If we are getting stats for the current thread, then add in the
  850          * stats that this thread has accumulated in its current time slice.
  851          * We reset the thread and CPU state as if we had performed a context
  852          * switch right here.
  853          */
  854         if (td == curthread) {
  855                 u = cpu_ticks();
  856                 runtime = u - PCPU_GET(switchtime);
  857                 td->td_runtime += runtime;
  858                 td->td_incruntime += runtime;
  859                 PCPU_SET(switchtime, u);
  860         }
  861         ruxagg(p, td);
  862         *ru = td->td_ru;
  863         calcru1(p, &td->td_rux, &ru->ru_utime, &ru->ru_stime);
  864 }
  865 
  866 static void
  867 calcru1(struct proc *p, struct rusage_ext *ruxp, struct timeval *up,
  868     struct timeval *sp)
  869 {
  870         /* {user, system, interrupt, total} {ticks, usec}: */
  871         uint64_t ut, uu, st, su, it, tt, tu;
  872 
  873         ut = ruxp->rux_uticks;
  874         st = ruxp->rux_sticks;
  875         it = ruxp->rux_iticks;
  876         tt = ut + st + it;
  877         if (tt == 0) {
  878                 /* Avoid divide by zero */
  879                 st = 1;
  880                 tt = 1;
  881         }
  882         tu = cputick2usec(ruxp->rux_runtime);
  883         if ((int64_t)tu < 0) {
  884                 /* XXX: this should be an assert /phk */
  885                 printf("calcru: negative runtime of %jd usec for pid %d (%s)\n",
  886                     (intmax_t)tu, p->p_pid, p->p_comm);
  887                 tu = ruxp->rux_tu;
  888         }
  889 
  890         if (tu >= ruxp->rux_tu) {
  891                 /*
  892                  * The normal case, time increased.
  893                  * Enforce monotonicity of bucketed numbers.
  894                  */
  895                 uu = (tu * ut) / tt;
  896                 if (uu < ruxp->rux_uu)
  897                         uu = ruxp->rux_uu;
  898                 su = (tu * st) / tt;
  899                 if (su < ruxp->rux_su)
  900                         su = ruxp->rux_su;
  901         } else if (tu + 3 > ruxp->rux_tu || 101 * tu > 100 * ruxp->rux_tu) {
  902                 /*
  903                  * When we calibrate the cputicker, it is not uncommon to
  904                  * see the presumably fixed frequency increase slightly over
  905                  * time as a result of thermal stabilization and NTP
  906                  * discipline (of the reference clock).  We therefore ignore
  907                  * a bit of backwards slop because we  expect to catch up
  908                  * shortly.  We use a 3 microsecond limit to catch low
  909                  * counts and a 1% limit for high counts.
  910                  */
  911                 uu = ruxp->rux_uu;
  912                 su = ruxp->rux_su;
  913                 tu = ruxp->rux_tu;
  914         } else { /* tu < ruxp->rux_tu */
  915                 /*
  916                  * What happened here was likely that a laptop, which ran at
  917                  * a reduced clock frequency at boot, kicked into high gear.
  918                  * The wisdom of spamming this message in that case is
  919                  * dubious, but it might also be indicative of something
  920                  * serious, so lets keep it and hope laptops can be made
  921                  * more truthful about their CPU speed via ACPI.
  922                  */
  923                 printf("calcru: runtime went backwards from %ju usec "
  924                     "to %ju usec for pid %d (%s)\n",
  925                     (uintmax_t)ruxp->rux_tu, (uintmax_t)tu,
  926                     p->p_pid, p->p_comm);
  927                 uu = (tu * ut) / tt;
  928                 su = (tu * st) / tt;
  929         }
  930 
  931         ruxp->rux_uu = uu;
  932         ruxp->rux_su = su;
  933         ruxp->rux_tu = tu;
  934 
  935         up->tv_sec = uu / 1000000;
  936         up->tv_usec = uu % 1000000;
  937         sp->tv_sec = su / 1000000;
  938         sp->tv_usec = su % 1000000;
  939 }
  940 
  941 #ifndef _SYS_SYSPROTO_H_
  942 struct getrusage_args {
  943         int     who;
  944         struct  rusage *rusage;
  945 };
  946 #endif
  947 int
  948 sys_getrusage(struct thread *td, struct getrusage_args *uap)
  949 {
  950         struct rusage ru;
  951         int error;
  952 
  953         error = kern_getrusage(td, uap->who, &ru);
  954         if (error == 0)
  955                 error = copyout(&ru, uap->rusage, sizeof(struct rusage));
  956         return (error);
  957 }
  958 
  959 int
  960 kern_getrusage(struct thread *td, int who, struct rusage *rup)
  961 {
  962         struct proc *p;
  963         int error;
  964 
  965         error = 0;
  966         p = td->td_proc;
  967         PROC_LOCK(p);
  968         switch (who) {
  969         case RUSAGE_SELF:
  970                 rufetchcalc(p, rup, &rup->ru_utime,
  971                     &rup->ru_stime);
  972                 break;
  973 
  974         case RUSAGE_CHILDREN:
  975                 *rup = p->p_stats->p_cru;
  976                 calccru(p, &rup->ru_utime, &rup->ru_stime);
  977                 break;
  978 
  979         case RUSAGE_THREAD:
  980                 PROC_STATLOCK(p);
  981                 thread_lock(td);
  982                 rufetchtd(td, rup);
  983                 thread_unlock(td);
  984                 PROC_STATUNLOCK(p);
  985                 break;
  986 
  987         default:
  988                 error = EINVAL;
  989         }
  990         PROC_UNLOCK(p);
  991         return (error);
  992 }
  993 
  994 void
  995 rucollect(struct rusage *ru, struct rusage *ru2)
  996 {
  997         long *ip, *ip2;
  998         int i;
  999 
 1000         if (ru->ru_maxrss < ru2->ru_maxrss)
 1001                 ru->ru_maxrss = ru2->ru_maxrss;
 1002         ip = &ru->ru_first;
 1003         ip2 = &ru2->ru_first;
 1004         for (i = &ru->ru_last - &ru->ru_first; i >= 0; i--)
 1005                 *ip++ += *ip2++;
 1006 }
 1007 
 1008 void
 1009 ruadd(struct rusage *ru, struct rusage_ext *rux, struct rusage *ru2,
 1010     struct rusage_ext *rux2)
 1011 {
 1012 
 1013         rux->rux_runtime += rux2->rux_runtime;
 1014         rux->rux_uticks += rux2->rux_uticks;
 1015         rux->rux_sticks += rux2->rux_sticks;
 1016         rux->rux_iticks += rux2->rux_iticks;
 1017         rux->rux_uu += rux2->rux_uu;
 1018         rux->rux_su += rux2->rux_su;
 1019         rux->rux_tu += rux2->rux_tu;
 1020         rucollect(ru, ru2);
 1021 }
 1022 
 1023 /*
 1024  * Aggregate tick counts into the proc's rusage_ext.
 1025  */
 1026 static void
 1027 ruxagg_locked(struct rusage_ext *rux, struct thread *td)
 1028 {
 1029 
 1030         THREAD_LOCK_ASSERT(td, MA_OWNED);
 1031         PROC_STATLOCK_ASSERT(td->td_proc, MA_OWNED);
 1032         rux->rux_runtime += td->td_incruntime;
 1033         rux->rux_uticks += td->td_uticks;
 1034         rux->rux_sticks += td->td_sticks;
 1035         rux->rux_iticks += td->td_iticks;
 1036 }
 1037 
 1038 void
 1039 ruxagg(struct proc *p, struct thread *td)
 1040 {
 1041 
 1042         thread_lock(td);
 1043         ruxagg_locked(&p->p_rux, td);
 1044         ruxagg_locked(&td->td_rux, td);
 1045         td->td_incruntime = 0;
 1046         td->td_uticks = 0;
 1047         td->td_iticks = 0;
 1048         td->td_sticks = 0;
 1049         thread_unlock(td);
 1050 }
 1051 
 1052 /*
 1053  * Update the rusage_ext structure and fetch a valid aggregate rusage
 1054  * for proc p if storage for one is supplied.
 1055  */
 1056 void
 1057 rufetch(struct proc *p, struct rusage *ru)
 1058 {
 1059         struct thread *td;
 1060 
 1061         PROC_STATLOCK_ASSERT(p, MA_OWNED);
 1062 
 1063         *ru = p->p_ru;
 1064         if (p->p_numthreads > 0)  {
 1065                 FOREACH_THREAD_IN_PROC(p, td) {
 1066                         ruxagg(p, td);
 1067                         rucollect(ru, &td->td_ru);
 1068                 }
 1069         }
 1070 }
 1071 
 1072 /*
 1073  * Atomically perform a rufetch and a calcru together.
 1074  * Consumers, can safely assume the calcru is executed only once
 1075  * rufetch is completed.
 1076  */
 1077 void
 1078 rufetchcalc(struct proc *p, struct rusage *ru, struct timeval *up,
 1079     struct timeval *sp)
 1080 {
 1081 
 1082         PROC_STATLOCK(p);
 1083         rufetch(p, ru);
 1084         calcru(p, up, sp);
 1085         PROC_STATUNLOCK(p);
 1086 }
 1087 
 1088 /*
 1089  * Allocate a new resource limits structure and initialize its
 1090  * reference count and mutex pointer.
 1091  */
 1092 struct plimit *
 1093 lim_alloc()
 1094 {
 1095         struct plimit *limp;
 1096 
 1097         limp = malloc(sizeof(struct plimit), M_PLIMIT, M_WAITOK);
 1098         refcount_init(&limp->pl_refcnt, 1);
 1099         return (limp);
 1100 }
 1101 
 1102 struct plimit *
 1103 lim_hold(struct plimit *limp)
 1104 {
 1105 
 1106         refcount_acquire(&limp->pl_refcnt);
 1107         return (limp);
 1108 }
 1109 
 1110 void
 1111 lim_fork(struct proc *p1, struct proc *p2)
 1112 {
 1113 
 1114         PROC_LOCK_ASSERT(p1, MA_OWNED);
 1115         PROC_LOCK_ASSERT(p2, MA_OWNED);
 1116 
 1117         p2->p_limit = lim_hold(p1->p_limit);
 1118         callout_init_mtx(&p2->p_limco, &p2->p_mtx, 0);
 1119         if (p1->p_cpulimit != RLIM_INFINITY)
 1120                 callout_reset_sbt(&p2->p_limco, SBT_1S, 0,
 1121                     lim_cb, p2, C_PREL(1));
 1122 }
 1123 
 1124 void
 1125 lim_free(struct plimit *limp)
 1126 {
 1127 
 1128         if (refcount_release(&limp->pl_refcnt))
 1129                 free((void *)limp, M_PLIMIT);
 1130 }
 1131 
 1132 /*
 1133  * Make a copy of the plimit structure.
 1134  * We share these structures copy-on-write after fork.
 1135  */
 1136 void
 1137 lim_copy(struct plimit *dst, struct plimit *src)
 1138 {
 1139 
 1140         KASSERT(dst->pl_refcnt <= 1, ("lim_copy to shared limit"));
 1141         bcopy(src->pl_rlimit, dst->pl_rlimit, sizeof(src->pl_rlimit));
 1142 }
 1143 
 1144 /*
 1145  * Return the hard limit for a particular system resource.  The
 1146  * which parameter specifies the index into the rlimit array.
 1147  */
 1148 rlim_t
 1149 lim_max(struct thread *td, int which)
 1150 {
 1151         struct rlimit rl;
 1152 
 1153         lim_rlimit(td, which, &rl);
 1154         return (rl.rlim_max);
 1155 }
 1156 
 1157 rlim_t
 1158 lim_max_proc(struct proc *p, int which)
 1159 {
 1160         struct rlimit rl;
 1161 
 1162         lim_rlimit_proc(p, which, &rl);
 1163         return (rl.rlim_max);
 1164 }
 1165 
 1166 /*
 1167  * Return the current (soft) limit for a particular system resource.
 1168  * The which parameter which specifies the index into the rlimit array
 1169  */
 1170 rlim_t
 1171 lim_cur(struct thread *td, int which)
 1172 {
 1173         struct rlimit rl;
 1174 
 1175         lim_rlimit(td, which, &rl);
 1176         return (rl.rlim_cur);
 1177 }
 1178 
 1179 rlim_t
 1180 lim_cur_proc(struct proc *p, int which)
 1181 {
 1182         struct rlimit rl;
 1183 
 1184         lim_rlimit_proc(p, which, &rl);
 1185         return (rl.rlim_cur);
 1186 }
 1187 
 1188 /*
 1189  * Return a copy of the entire rlimit structure for the system limit
 1190  * specified by 'which' in the rlimit structure pointed to by 'rlp'.
 1191  */
 1192 void
 1193 lim_rlimit(struct thread *td, int which, struct rlimit *rlp)
 1194 {
 1195         struct proc *p = td->td_proc;
 1196 
 1197         MPASS(td == curthread);
 1198         KASSERT(which >= 0 && which < RLIM_NLIMITS,
 1199             ("request for invalid resource limit"));
 1200         *rlp = td->td_limit->pl_rlimit[which];
 1201         if (p->p_sysent->sv_fixlimit != NULL)
 1202                 p->p_sysent->sv_fixlimit(rlp, which);
 1203 }
 1204 
 1205 void
 1206 lim_rlimit_proc(struct proc *p, int which, struct rlimit *rlp)
 1207 {
 1208 
 1209         PROC_LOCK_ASSERT(p, MA_OWNED);
 1210         KASSERT(which >= 0 && which < RLIM_NLIMITS,
 1211             ("request for invalid resource limit"));
 1212         *rlp = p->p_limit->pl_rlimit[which];
 1213         if (p->p_sysent->sv_fixlimit != NULL)
 1214                 p->p_sysent->sv_fixlimit(rlp, which);
 1215 }
 1216 
 1217 void
 1218 uihashinit()
 1219 {
 1220 
 1221         uihashtbl = hashinit(maxproc / 16, M_UIDINFO, &uihash);
 1222         rw_init(&uihashtbl_lock, "uidinfo hash");
 1223 }
 1224 
 1225 /*
 1226  * Look up a uidinfo struct for the parameter uid.
 1227  * uihashtbl_lock must be locked.
 1228  * Increase refcount on uidinfo struct returned.
 1229  */
 1230 static struct uidinfo *
 1231 uilookup(uid_t uid)
 1232 {
 1233         struct uihashhead *uipp;
 1234         struct uidinfo *uip;
 1235 
 1236         rw_assert(&uihashtbl_lock, RA_LOCKED);
 1237         uipp = UIHASH(uid);
 1238         LIST_FOREACH(uip, uipp, ui_hash)
 1239                 if (uip->ui_uid == uid) {
 1240                         uihold(uip);
 1241                         break;
 1242                 }
 1243 
 1244         return (uip);
 1245 }
 1246 
 1247 /*
 1248  * Find or allocate a struct uidinfo for a particular uid.
 1249  * Returns with uidinfo struct referenced.
 1250  * uifree() should be called on a struct uidinfo when released.
 1251  */
 1252 struct uidinfo *
 1253 uifind(uid_t uid)
 1254 {
 1255         struct uidinfo *new_uip, *uip;
 1256         struct ucred *cred;
 1257 
 1258         cred = curthread->td_ucred;
 1259         if (cred->cr_uidinfo->ui_uid == uid) {
 1260                 uip = cred->cr_uidinfo;
 1261                 uihold(uip);
 1262                 return (uip);
 1263         } else if (cred->cr_ruidinfo->ui_uid == uid) {
 1264                 uip = cred->cr_ruidinfo;
 1265                 uihold(uip);
 1266                 return (uip);
 1267         }
 1268 
 1269         rw_rlock(&uihashtbl_lock);
 1270         uip = uilookup(uid);
 1271         rw_runlock(&uihashtbl_lock);
 1272         if (uip != NULL)
 1273                 return (uip);
 1274 
 1275         new_uip = malloc(sizeof(*new_uip), M_UIDINFO, M_WAITOK | M_ZERO);
 1276         racct_create(&new_uip->ui_racct);
 1277         refcount_init(&new_uip->ui_ref, 1);
 1278         new_uip->ui_uid = uid;
 1279 
 1280         rw_wlock(&uihashtbl_lock);
 1281         /*
 1282          * There's a chance someone created our uidinfo while we
 1283          * were in malloc and not holding the lock, so we have to
 1284          * make sure we don't insert a duplicate uidinfo.
 1285          */
 1286         if ((uip = uilookup(uid)) == NULL) {
 1287                 LIST_INSERT_HEAD(UIHASH(uid), new_uip, ui_hash);
 1288                 rw_wunlock(&uihashtbl_lock);
 1289                 uip = new_uip;
 1290         } else {
 1291                 rw_wunlock(&uihashtbl_lock);
 1292                 racct_destroy(&new_uip->ui_racct);
 1293                 free(new_uip, M_UIDINFO);
 1294         }
 1295         return (uip);
 1296 }
 1297 
 1298 /*
 1299  * Place another refcount on a uidinfo struct.
 1300  */
 1301 void
 1302 uihold(struct uidinfo *uip)
 1303 {
 1304 
 1305         refcount_acquire(&uip->ui_ref);
 1306 }
 1307 
 1308 /*-
 1309  * Since uidinfo structs have a long lifetime, we use an
 1310  * opportunistic refcounting scheme to avoid locking the lookup hash
 1311  * for each release.
 1312  *
 1313  * If the refcount hits 0, we need to free the structure,
 1314  * which means we need to lock the hash.
 1315  * Optimal case:
 1316  *   After locking the struct and lowering the refcount, if we find
 1317  *   that we don't need to free, simply unlock and return.
 1318  * Suboptimal case:
 1319  *   If refcount lowering results in need to free, bump the count
 1320  *   back up, lose the lock and acquire the locks in the proper
 1321  *   order to try again.
 1322  */
 1323 void
 1324 uifree(struct uidinfo *uip)
 1325 {
 1326         int old;
 1327 
 1328         /* Prepare for optimal case. */
 1329         old = uip->ui_ref;
 1330         if (old > 1 && atomic_cmpset_int(&uip->ui_ref, old, old - 1))
 1331                 return;
 1332 
 1333         /* Prepare for suboptimal case. */
 1334         rw_wlock(&uihashtbl_lock);
 1335         if (refcount_release(&uip->ui_ref) == 0) {
 1336                 rw_wunlock(&uihashtbl_lock);
 1337                 return;
 1338         }
 1339 
 1340         racct_destroy(&uip->ui_racct);
 1341         LIST_REMOVE(uip, ui_hash);
 1342         rw_wunlock(&uihashtbl_lock);
 1343 
 1344         if (uip->ui_sbsize != 0)
 1345                 printf("freeing uidinfo: uid = %d, sbsize = %ld\n",
 1346                     uip->ui_uid, uip->ui_sbsize);
 1347         if (uip->ui_proccnt != 0)
 1348                 printf("freeing uidinfo: uid = %d, proccnt = %ld\n",
 1349                     uip->ui_uid, uip->ui_proccnt);
 1350         if (uip->ui_vmsize != 0)
 1351                 printf("freeing uidinfo: uid = %d, swapuse = %lld\n",
 1352                     uip->ui_uid, (unsigned long long)uip->ui_vmsize);
 1353         free(uip, M_UIDINFO);
 1354 }
 1355 
 1356 #ifdef RACCT
 1357 void
 1358 ui_racct_foreach(void (*callback)(struct racct *racct,
 1359     void *arg2, void *arg3), void (*pre)(void), void (*post)(void),
 1360     void *arg2, void *arg3)
 1361 {
 1362         struct uidinfo *uip;
 1363         struct uihashhead *uih;
 1364 
 1365         rw_rlock(&uihashtbl_lock);
 1366         if (pre != NULL)
 1367                 (pre)();
 1368         for (uih = &uihashtbl[uihash]; uih >= uihashtbl; uih--) {
 1369                 LIST_FOREACH(uip, uih, ui_hash) {
 1370                         (callback)(uip->ui_racct, arg2, arg3);
 1371                 }
 1372         }
 1373         if (post != NULL)
 1374                 (post)();
 1375         rw_runlock(&uihashtbl_lock);
 1376 }
 1377 #endif
 1378 
 1379 static inline int
 1380 chglimit(struct uidinfo *uip, long *limit, int diff, rlim_t max, const char *name)
 1381 {
 1382         long new;
 1383 
 1384         /* Don't allow them to exceed max, but allow subtraction. */
 1385         new = atomic_fetchadd_long(limit, (long)diff) + diff;
 1386         if (diff > 0 && max != 0) {
 1387                 if (new < 0 || new > max) {
 1388                         atomic_subtract_long(limit, (long)diff);
 1389                         return (0);
 1390                 }
 1391         } else if (new < 0)
 1392                 printf("negative %s for uid = %d\n", name, uip->ui_uid);
 1393         return (1);
 1394 }
 1395 
 1396 /*
 1397  * Change the count associated with number of processes
 1398  * a given user is using.  When 'max' is 0, don't enforce a limit
 1399  */
 1400 int
 1401 chgproccnt(struct uidinfo *uip, int diff, rlim_t max)
 1402 {
 1403 
 1404         return (chglimit(uip, &uip->ui_proccnt, diff, max, "proccnt"));
 1405 }
 1406 
 1407 /*
 1408  * Change the total socket buffer size a user has used.
 1409  */
 1410 int
 1411 chgsbsize(struct uidinfo *uip, u_int *hiwat, u_int to, rlim_t max)
 1412 {
 1413         int diff, rv;
 1414 
 1415         diff = to - *hiwat;
 1416         if (diff > 0 && max == 0) {
 1417                 rv = 0;
 1418         } else {
 1419                 rv = chglimit(uip, &uip->ui_sbsize, diff, max, "sbsize");
 1420                 if (rv != 0)
 1421                         *hiwat = to;
 1422         }
 1423         return (rv);
 1424 }
 1425 
 1426 /*
 1427  * Change the count associated with number of pseudo-terminals
 1428  * a given user is using.  When 'max' is 0, don't enforce a limit
 1429  */
 1430 int
 1431 chgptscnt(struct uidinfo *uip, int diff, rlim_t max)
 1432 {
 1433 
 1434         return (chglimit(uip, &uip->ui_ptscnt, diff, max, "ptscnt"));
 1435 }
 1436 
 1437 int
 1438 chgkqcnt(struct uidinfo *uip, int diff, rlim_t max)
 1439 {
 1440 
 1441         return (chglimit(uip, &uip->ui_kqcnt, diff, max, "kqcnt"));
 1442 }
 1443 
 1444 int
 1445 chgumtxcnt(struct uidinfo *uip, int diff, rlim_t max)
 1446 {
 1447 
 1448         return (chglimit(uip, &uip->ui_umtxcnt, diff, max, "umtxcnt"));
 1449 }

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