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

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    1 /*-
    2  * Implementation of SVID semaphores
    3  *
    4  * Author:  Daniel Boulet
    5  *
    6  * This software is provided ``AS IS'' without any warranties of any kind.
    7  */
    8 /*-
    9  * Copyright (c) 2003-2005 McAfee, Inc.
   10  * All rights reserved.
   11  *
   12  * This software was developed for the FreeBSD Project in part by McAfee
   13  * Research, the Security Research Division of McAfee, Inc under DARPA/SPAWAR
   14  * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS research
   15  * program.
   16  *
   17  * Redistribution and use in source and binary forms, with or without
   18  * modification, are permitted provided that the following conditions
   19  * are met:
   20  * 1. Redistributions of source code must retain the above copyright
   21  *    notice, this list of conditions and the following disclaimer.
   22  * 2. Redistributions in binary form must reproduce the above copyright
   23  *    notice, this list of conditions and the following disclaimer in the
   24  *    documentation and/or other materials provided with the distribution.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD$");
   41 
   42 #include "opt_sysvipc.h"
   43 #include "opt_mac.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/sysproto.h>
   48 #include <sys/eventhandler.h>
   49 #include <sys/kernel.h>
   50 #include <sys/proc.h>
   51 #include <sys/lock.h>
   52 #include <sys/module.h>
   53 #include <sys/mutex.h>
   54 #include <sys/sem.h>
   55 #include <sys/syscall.h>
   56 #include <sys/syscallsubr.h>
   57 #include <sys/sysent.h>
   58 #include <sys/sysctl.h>
   59 #include <sys/uio.h>
   60 #include <sys/malloc.h>
   61 #include <sys/jail.h>
   62 
   63 #include <security/mac/mac_framework.h>
   64 
   65 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
   66 
   67 #ifdef SEM_DEBUG
   68 #define DPRINTF(a)      printf a
   69 #else
   70 #define DPRINTF(a)
   71 #endif
   72 
   73 static void seminit(void);
   74 static int sysvsem_modload(struct module *, int, void *);
   75 static int semunload(void);
   76 static void semexit_myhook(void *arg, struct proc *p);
   77 static int sysctl_sema(SYSCTL_HANDLER_ARGS);
   78 static int semvalid(int semid, struct semid_kernel *semakptr);
   79 
   80 #ifndef _SYS_SYSPROTO_H_
   81 struct __semctl_args;
   82 int __semctl(struct thread *td, struct __semctl_args *uap);
   83 struct semget_args;
   84 int semget(struct thread *td, struct semget_args *uap);
   85 struct semop_args;
   86 int semop(struct thread *td, struct semop_args *uap);
   87 #endif
   88 
   89 static struct sem_undo *semu_alloc(struct thread *td);
   90 static int semundo_adjust(struct thread *td, struct sem_undo **supptr,
   91                 int semid, int semnum, int adjval);
   92 static void semundo_clear(int semid, int semnum);
   93 
   94 /* XXX casting to (sy_call_t *) is bogus, as usual. */
   95 static sy_call_t *semcalls[] = {
   96         (sy_call_t *)__semctl, (sy_call_t *)semget,
   97         (sy_call_t *)semop
   98 };
   99 
  100 static struct mtx       sem_mtx;        /* semaphore global lock */
  101 static int      semtot = 0;
  102 static struct semid_kernel *sema;       /* semaphore id pool */
  103 static struct mtx *sema_mtx;    /* semaphore id pool mutexes*/
  104 static struct sem *sem;         /* semaphore pool */
  105 SLIST_HEAD(, sem_undo) semu_list;       /* list of active undo structures */
  106 static int      *semu;          /* undo structure pool */
  107 static eventhandler_tag semexit_tag;
  108 
  109 #define SEMUNDO_MTX             sem_mtx
  110 #define SEMUNDO_LOCK()          mtx_lock(&SEMUNDO_MTX);
  111 #define SEMUNDO_UNLOCK()        mtx_unlock(&SEMUNDO_MTX);
  112 #define SEMUNDO_LOCKASSERT(how) mtx_assert(&SEMUNDO_MTX, (how));
  113 
  114 struct sem {
  115         u_short semval;         /* semaphore value */
  116         pid_t   sempid;         /* pid of last operation */
  117         u_short semncnt;        /* # awaiting semval > cval */
  118         u_short semzcnt;        /* # awaiting semval = 0 */
  119 };
  120 
  121 /*
  122  * Undo structure (one per process)
  123  */
  124 struct sem_undo {
  125         SLIST_ENTRY(sem_undo) un_next;  /* ptr to next active undo structure */
  126         struct  proc *un_proc;          /* owner of this structure */
  127         short   un_cnt;                 /* # of active entries */
  128         struct undo {
  129                 short   un_adjval;      /* adjust on exit values */
  130                 short   un_num;         /* semaphore # */
  131                 int     un_id;          /* semid */
  132         } un_ent[1];                    /* undo entries */
  133 };
  134 
  135 /*
  136  * Configuration parameters
  137  */
  138 #ifndef SEMMNI
  139 #define SEMMNI  10              /* # of semaphore identifiers */
  140 #endif
  141 #ifndef SEMMNS
  142 #define SEMMNS  60              /* # of semaphores in system */
  143 #endif
  144 #ifndef SEMUME
  145 #define SEMUME  10              /* max # of undo entries per process */
  146 #endif
  147 #ifndef SEMMNU
  148 #define SEMMNU  30              /* # of undo structures in system */
  149 #endif
  150 
  151 /* shouldn't need tuning */
  152 #ifndef SEMMAP
  153 #define SEMMAP  30              /* # of entries in semaphore map */
  154 #endif
  155 #ifndef SEMMSL
  156 #define SEMMSL  SEMMNS          /* max # of semaphores per id */
  157 #endif
  158 #ifndef SEMOPM
  159 #define SEMOPM  100             /* max # of operations per semop call */
  160 #endif
  161 
  162 #define SEMVMX  32767           /* semaphore maximum value */
  163 #define SEMAEM  16384           /* adjust on exit max value */
  164 
  165 /*
  166  * Due to the way semaphore memory is allocated, we have to ensure that
  167  * SEMUSZ is properly aligned.
  168  */
  169 
  170 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
  171 
  172 /* actual size of an undo structure */
  173 #define SEMUSZ  SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
  174 
  175 /*
  176  * Macro to find a particular sem_undo vector
  177  */
  178 #define SEMU(ix) \
  179         ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
  180 
  181 /*
  182  * semaphore info struct
  183  */
  184 struct seminfo seminfo = {
  185                 SEMMAP,         /* # of entries in semaphore map */
  186                 SEMMNI,         /* # of semaphore identifiers */
  187                 SEMMNS,         /* # of semaphores in system */
  188                 SEMMNU,         /* # of undo structures in system */
  189                 SEMMSL,         /* max # of semaphores per id */
  190                 SEMOPM,         /* max # of operations per semop call */
  191                 SEMUME,         /* max # of undo entries per process */
  192                 SEMUSZ,         /* size in bytes of undo structure */
  193                 SEMVMX,         /* semaphore maximum value */
  194                 SEMAEM          /* adjust on exit max value */
  195 };
  196 
  197 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0,
  198     "Number of entries in the semaphore map");
  199 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RDTUN, &seminfo.semmni, 0,
  200     "Number of semaphore identifiers");
  201 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RDTUN, &seminfo.semmns, 0,
  202     "Maximum number of semaphores in the system");
  203 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RDTUN, &seminfo.semmnu, 0,
  204     "Maximum number of undo structures in the system");
  205 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0,
  206     "Max semaphores per id");
  207 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RDTUN, &seminfo.semopm, 0,
  208     "Max operations per semop call");
  209 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RDTUN, &seminfo.semume, 0,
  210     "Max undo entries per process");
  211 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RDTUN, &seminfo.semusz, 0,
  212     "Size in bytes of undo structure");
  213 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0,
  214     "Semaphore maximum value");
  215 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0,
  216     "Adjust on exit max value");
  217 SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLFLAG_RD,
  218     NULL, 0, sysctl_sema, "", "");
  219 
  220 static void
  221 seminit(void)
  222 {
  223         int i;
  224 
  225         TUNABLE_INT_FETCH("kern.ipc.semmap", &seminfo.semmap);
  226         TUNABLE_INT_FETCH("kern.ipc.semmni", &seminfo.semmni);
  227         TUNABLE_INT_FETCH("kern.ipc.semmns", &seminfo.semmns);
  228         TUNABLE_INT_FETCH("kern.ipc.semmnu", &seminfo.semmnu);
  229         TUNABLE_INT_FETCH("kern.ipc.semmsl", &seminfo.semmsl);
  230         TUNABLE_INT_FETCH("kern.ipc.semopm", &seminfo.semopm);
  231         TUNABLE_INT_FETCH("kern.ipc.semume", &seminfo.semume);
  232         TUNABLE_INT_FETCH("kern.ipc.semusz", &seminfo.semusz);
  233         TUNABLE_INT_FETCH("kern.ipc.semvmx", &seminfo.semvmx);
  234         TUNABLE_INT_FETCH("kern.ipc.semaem", &seminfo.semaem);
  235 
  236         sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
  237         sema = malloc(sizeof(struct semid_kernel) * seminfo.semmni, M_SEM,
  238             M_WAITOK);
  239         sema_mtx = malloc(sizeof(struct mtx) * seminfo.semmni, M_SEM,
  240             M_WAITOK | M_ZERO);
  241         semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
  242 
  243         for (i = 0; i < seminfo.semmni; i++) {
  244                 sema[i].u.sem_base = 0;
  245                 sema[i].u.sem_perm.mode = 0;
  246                 sema[i].u.sem_perm.seq = 0;
  247 #ifdef MAC
  248                 mac_init_sysv_sem(&sema[i]);
  249 #endif
  250         }
  251         for (i = 0; i < seminfo.semmni; i++)
  252                 mtx_init(&sema_mtx[i], "semid", NULL, MTX_DEF);
  253         for (i = 0; i < seminfo.semmnu; i++) {
  254                 struct sem_undo *suptr = SEMU(i);
  255                 suptr->un_proc = NULL;
  256         }
  257         SLIST_INIT(&semu_list);
  258         mtx_init(&sem_mtx, "sem", NULL, MTX_DEF);
  259         semexit_tag = EVENTHANDLER_REGISTER(process_exit, semexit_myhook, NULL,
  260             EVENTHANDLER_PRI_ANY);
  261 }
  262 
  263 static int
  264 semunload(void)
  265 {
  266         int i;
  267 
  268         if (semtot != 0)
  269                 return (EBUSY);
  270 
  271         EVENTHANDLER_DEREGISTER(process_exit, semexit_tag);
  272 #ifdef MAC
  273         for (i = 0; i < seminfo.semmni; i++)
  274                 mac_destroy_sysv_sem(&sema[i]);
  275 #endif
  276         free(sem, M_SEM);
  277         free(sema, M_SEM);
  278         free(semu, M_SEM);
  279         for (i = 0; i < seminfo.semmni; i++)
  280                 mtx_destroy(&sema_mtx[i]);
  281         mtx_destroy(&sem_mtx);
  282         return (0);
  283 }
  284 
  285 static int
  286 sysvsem_modload(struct module *module, int cmd, void *arg)
  287 {
  288         int error = 0;
  289 
  290         switch (cmd) {
  291         case MOD_LOAD:
  292                 seminit();
  293                 break;
  294         case MOD_UNLOAD:
  295                 error = semunload();
  296                 break;
  297         case MOD_SHUTDOWN:
  298                 break;
  299         default:
  300                 error = EINVAL;
  301                 break;
  302         }
  303         return (error);
  304 }
  305 
  306 static moduledata_t sysvsem_mod = {
  307         "sysvsem",
  308         &sysvsem_modload,
  309         NULL
  310 };
  311 
  312 SYSCALL_MODULE_HELPER(semsys);
  313 SYSCALL_MODULE_HELPER(__semctl);
  314 SYSCALL_MODULE_HELPER(semget);
  315 SYSCALL_MODULE_HELPER(semop);
  316 
  317 DECLARE_MODULE(sysvsem, sysvsem_mod,
  318         SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
  319 MODULE_VERSION(sysvsem, 1);
  320 
  321 /*
  322  * Entry point for all SEM calls.
  323  */
  324 int
  325 semsys(td, uap)
  326         struct thread *td;
  327         /* XXX actually varargs. */
  328         struct semsys_args /* {
  329                 int     which;
  330                 int     a2;
  331                 int     a3;
  332                 int     a4;
  333                 int     a5;
  334         } */ *uap;
  335 {
  336         int error;
  337 
  338         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
  339                 return (ENOSYS);
  340         if (uap->which < 0 ||
  341             uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
  342                 return (EINVAL);
  343         error = (*semcalls[uap->which])(td, &uap->a2);
  344         return (error);
  345 }
  346 
  347 /*
  348  * Allocate a new sem_undo structure for a process
  349  * (returns ptr to structure or NULL if no more room)
  350  */
  351 
  352 static struct sem_undo *
  353 semu_alloc(td)
  354         struct thread *td;
  355 {
  356         int i;
  357         struct sem_undo *suptr;
  358         struct sem_undo **supptr;
  359         int attempt;
  360 
  361         SEMUNDO_LOCKASSERT(MA_OWNED);
  362         /*
  363          * Try twice to allocate something.
  364          * (we'll purge an empty structure after the first pass so
  365          * two passes are always enough)
  366          */
  367 
  368         for (attempt = 0; attempt < 2; attempt++) {
  369                 /*
  370                  * Look for a free structure.
  371                  * Fill it in and return it if we find one.
  372                  */
  373 
  374                 for (i = 0; i < seminfo.semmnu; i++) {
  375                         suptr = SEMU(i);
  376                         if (suptr->un_proc == NULL) {
  377                                 SLIST_INSERT_HEAD(&semu_list, suptr, un_next);
  378                                 suptr->un_cnt = 0;
  379                                 suptr->un_proc = td->td_proc;
  380                                 return(suptr);
  381                         }
  382                 }
  383 
  384                 /*
  385                  * We didn't find a free one, if this is the first attempt
  386                  * then try to free a structure.
  387                  */
  388 
  389                 if (attempt == 0) {
  390                         /* All the structures are in use - try to free one */
  391                         int did_something = 0;
  392 
  393                         SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list,
  394                             un_next) {
  395                                 if (suptr->un_cnt == 0) {
  396                                         suptr->un_proc = NULL;
  397                                         did_something = 1;
  398                                         *supptr = SLIST_NEXT(suptr, un_next);
  399                                         break;
  400                                 }
  401                         }
  402 
  403                         /* If we didn't free anything then just give-up */
  404                         if (!did_something)
  405                                 return(NULL);
  406                 } else {
  407                         /*
  408                          * The second pass failed even though we freed
  409                          * something after the first pass!
  410                          * This is IMPOSSIBLE!
  411                          */
  412                         panic("semu_alloc - second attempt failed");
  413                 }
  414         }
  415         return (NULL);
  416 }
  417 
  418 /*
  419  * Adjust a particular entry for a particular proc
  420  */
  421 
  422 static int
  423 semundo_adjust(td, supptr, semid, semnum, adjval)
  424         struct thread *td;
  425         struct sem_undo **supptr;
  426         int semid, semnum;
  427         int adjval;
  428 {
  429         struct proc *p = td->td_proc;
  430         struct sem_undo *suptr;
  431         struct undo *sunptr;
  432         int i;
  433 
  434         SEMUNDO_LOCKASSERT(MA_OWNED);
  435         /* Look for and remember the sem_undo if the caller doesn't provide
  436            it */
  437 
  438         suptr = *supptr;
  439         if (suptr == NULL) {
  440                 SLIST_FOREACH(suptr, &semu_list, un_next) {
  441                         if (suptr->un_proc == p) {
  442                                 *supptr = suptr;
  443                                 break;
  444                         }
  445                 }
  446                 if (suptr == NULL) {
  447                         if (adjval == 0)
  448                                 return(0);
  449                         suptr = semu_alloc(td);
  450                         if (suptr == NULL)
  451                                 return(ENOSPC);
  452                         *supptr = suptr;
  453                 }
  454         }
  455 
  456         /*
  457          * Look for the requested entry and adjust it (delete if adjval becomes
  458          * 0).
  459          */
  460         sunptr = &suptr->un_ent[0];
  461         for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
  462                 if (sunptr->un_id != semid || sunptr->un_num != semnum)
  463                         continue;
  464                 if (adjval != 0) {
  465                         adjval += sunptr->un_adjval;
  466                         if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
  467                                 return (ERANGE);
  468                 }
  469                 sunptr->un_adjval = adjval;
  470                 if (sunptr->un_adjval == 0) {
  471                         suptr->un_cnt--;
  472                         if (i < suptr->un_cnt)
  473                                 suptr->un_ent[i] =
  474                                     suptr->un_ent[suptr->un_cnt];
  475                 }
  476                 return(0);
  477         }
  478 
  479         /* Didn't find the right entry - create it */
  480         if (adjval == 0)
  481                 return(0);
  482         if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
  483                 return (ERANGE);
  484         if (suptr->un_cnt != seminfo.semume) {
  485                 sunptr = &suptr->un_ent[suptr->un_cnt];
  486                 suptr->un_cnt++;
  487                 sunptr->un_adjval = adjval;
  488                 sunptr->un_id = semid; sunptr->un_num = semnum;
  489         } else
  490                 return(EINVAL);
  491         return(0);
  492 }
  493 
  494 static void
  495 semundo_clear(semid, semnum)
  496         int semid, semnum;
  497 {
  498         struct sem_undo *suptr;
  499 
  500         SEMUNDO_LOCKASSERT(MA_OWNED);
  501         SLIST_FOREACH(suptr, &semu_list, un_next) {
  502                 struct undo *sunptr = &suptr->un_ent[0];
  503                 int i = 0;
  504 
  505                 while (i < suptr->un_cnt) {
  506                         if (sunptr->un_id == semid) {
  507                                 if (semnum == -1 || sunptr->un_num == semnum) {
  508                                         suptr->un_cnt--;
  509                                         if (i < suptr->un_cnt) {
  510                                                 suptr->un_ent[i] =
  511                                                   suptr->un_ent[suptr->un_cnt];
  512                                                 continue;
  513                                         }
  514                                 }
  515                                 if (semnum != -1)
  516                                         break;
  517                         }
  518                         i++, sunptr++;
  519                 }
  520         }
  521 }
  522 
  523 static int
  524 semvalid(semid, semakptr)
  525         int semid;
  526         struct semid_kernel *semakptr;
  527 {
  528 
  529         return ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
  530             semakptr->u.sem_perm.seq != IPCID_TO_SEQ(semid) ? EINVAL : 0);
  531 }
  532 
  533 /*
  534  * Note that the user-mode half of this passes a union, not a pointer.
  535  */
  536 #ifndef _SYS_SYSPROTO_H_
  537 struct __semctl_args {
  538         int     semid;
  539         int     semnum;
  540         int     cmd;
  541         union   semun *arg;
  542 };
  543 #endif
  544 int
  545 __semctl(td, uap)
  546         struct thread *td;
  547         struct __semctl_args *uap;
  548 {
  549         struct semid_ds dsbuf;
  550         union semun arg, semun;
  551         register_t rval;
  552         int error;
  553 
  554         switch (uap->cmd) {
  555         case SEM_STAT:
  556         case IPC_SET:
  557         case IPC_STAT:
  558         case GETALL:
  559         case SETVAL:
  560         case SETALL:
  561                 error = copyin(uap->arg, &arg, sizeof(arg));
  562                 if (error)
  563                         return (error);
  564                 break;
  565         }
  566 
  567         switch (uap->cmd) {
  568         case SEM_STAT:
  569         case IPC_STAT:
  570                 semun.buf = &dsbuf;
  571                 break;
  572         case IPC_SET:
  573                 error = copyin(arg.buf, &dsbuf, sizeof(dsbuf));
  574                 if (error)
  575                         return (error);
  576                 semun.buf = &dsbuf;
  577                 break;
  578         case GETALL:
  579         case SETALL:
  580                 semun.array = arg.array;
  581                 break;
  582         case SETVAL:
  583                 semun.val = arg.val;
  584                 break;          
  585         }
  586 
  587         error = kern_semctl(td, uap->semid, uap->semnum, uap->cmd, &semun,
  588             &rval);
  589         if (error)
  590                 return (error);
  591 
  592         switch (uap->cmd) {
  593         case SEM_STAT:
  594         case IPC_STAT:
  595                 error = copyout(&dsbuf, arg.buf, sizeof(dsbuf));
  596                 break;
  597         }
  598 
  599         if (error == 0)
  600                 td->td_retval[0] = rval;
  601         return (error);
  602 }
  603 
  604 int
  605 kern_semctl(struct thread *td, int semid, int semnum, int cmd,
  606     union semun *arg, register_t *rval)
  607 {
  608         u_short *array;
  609         struct ucred *cred = td->td_ucred;
  610         int i, error;
  611         struct semid_ds *sbuf;
  612         struct semid_kernel *semakptr;
  613         struct mtx *sema_mtxp;
  614         u_short usval, count;
  615         int semidx;
  616 
  617         DPRINTF(("call to semctl(%d, %d, %d, 0x%p)\n",
  618             semid, semnum, cmd, arg));
  619         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
  620                 return (ENOSYS);
  621 
  622         array = NULL;
  623 
  624         switch(cmd) {
  625         case SEM_STAT:
  626                 /*
  627                  * For this command we assume semid is an array index
  628                  * rather than an IPC id.
  629                  */
  630                 if (semid < 0 || semid >= seminfo.semmni)
  631                         return (EINVAL);
  632                 semakptr = &sema[semid];
  633                 sema_mtxp = &sema_mtx[semid];
  634                 mtx_lock(sema_mtxp);
  635                 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
  636                         error = EINVAL;
  637                         goto done2;
  638                 }
  639                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  640                         goto done2;
  641 #ifdef MAC
  642                 error = mac_check_sysv_semctl(cred, semakptr, cmd);
  643                 if (error != 0)
  644                         goto done2;
  645 #endif
  646                 bcopy(&semakptr->u, arg->buf, sizeof(struct semid_ds));
  647                 *rval = IXSEQ_TO_IPCID(semid, semakptr->u.sem_perm);
  648                 mtx_unlock(sema_mtxp);
  649                 return (0);
  650         }
  651 
  652         semidx = IPCID_TO_IX(semid);
  653         if (semidx < 0 || semidx >= seminfo.semmni)
  654                 return (EINVAL);
  655 
  656         semakptr = &sema[semidx];
  657         sema_mtxp = &sema_mtx[semidx];
  658         mtx_lock(sema_mtxp);
  659 #ifdef MAC
  660         error = mac_check_sysv_semctl(cred, semakptr, cmd);
  661         if (error != 0)
  662                 goto done2;
  663 #endif
  664 
  665         error = 0;
  666         *rval = 0;
  667 
  668         switch (cmd) {
  669         case IPC_RMID:
  670                 if ((error = semvalid(semid, semakptr)) != 0)
  671                         goto done2;
  672                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
  673                         goto done2;
  674                 semakptr->u.sem_perm.cuid = cred->cr_uid;
  675                 semakptr->u.sem_perm.uid = cred->cr_uid;
  676                 semtot -= semakptr->u.sem_nsems;
  677                 for (i = semakptr->u.sem_base - sem; i < semtot; i++)
  678                         sem[i] = sem[i + semakptr->u.sem_nsems];
  679                 for (i = 0; i < seminfo.semmni; i++) {
  680                         if ((sema[i].u.sem_perm.mode & SEM_ALLOC) &&
  681                             sema[i].u.sem_base > semakptr->u.sem_base)
  682                                 sema[i].u.sem_base -= semakptr->u.sem_nsems;
  683                 }
  684                 semakptr->u.sem_perm.mode = 0;
  685 #ifdef MAC
  686                 mac_cleanup_sysv_sem(semakptr);
  687 #endif
  688                 SEMUNDO_LOCK();
  689                 semundo_clear(semidx, -1);
  690                 SEMUNDO_UNLOCK();
  691                 wakeup(semakptr);
  692                 break;
  693 
  694         case IPC_SET:
  695                 if ((error = semvalid(semid, semakptr)) != 0)
  696                         goto done2;
  697                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
  698                         goto done2;
  699                 sbuf = arg->buf;
  700                 semakptr->u.sem_perm.uid = sbuf->sem_perm.uid;
  701                 semakptr->u.sem_perm.gid = sbuf->sem_perm.gid;
  702                 semakptr->u.sem_perm.mode = (semakptr->u.sem_perm.mode &
  703                     ~0777) | (sbuf->sem_perm.mode & 0777);
  704                 semakptr->u.sem_ctime = time_second;
  705                 break;
  706 
  707         case IPC_STAT:
  708                 if ((error = semvalid(semid, semakptr)) != 0)
  709                         goto done2;
  710                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  711                         goto done2;
  712                 bcopy(&semakptr->u, arg->buf, sizeof(struct semid_ds));
  713                 break;
  714 
  715         case GETNCNT:
  716                 if ((error = semvalid(semid, semakptr)) != 0)
  717                         goto done2;
  718                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  719                         goto done2;
  720                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  721                         error = EINVAL;
  722                         goto done2;
  723                 }
  724                 *rval = semakptr->u.sem_base[semnum].semncnt;
  725                 break;
  726 
  727         case GETPID:
  728                 if ((error = semvalid(semid, semakptr)) != 0)
  729                         goto done2;
  730                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  731                         goto done2;
  732                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  733                         error = EINVAL;
  734                         goto done2;
  735                 }
  736                 *rval = semakptr->u.sem_base[semnum].sempid;
  737                 break;
  738 
  739         case GETVAL:
  740                 if ((error = semvalid(semid, semakptr)) != 0)
  741                         goto done2;
  742                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  743                         goto done2;
  744                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  745                         error = EINVAL;
  746                         goto done2;
  747                 }
  748                 *rval = semakptr->u.sem_base[semnum].semval;
  749                 break;
  750 
  751         case GETALL:
  752                 /*
  753                  * Unfortunately, callers of this function don't know
  754                  * in advance how many semaphores are in this set.
  755                  * While we could just allocate the maximum size array
  756                  * and pass the actual size back to the caller, that
  757                  * won't work for SETALL since we can't copyin() more
  758                  * data than the user specified as we may return a
  759                  * spurious EFAULT.
  760                  * 
  761                  * Note that the number of semaphores in a set is
  762                  * fixed for the life of that set.  The only way that
  763                  * the 'count' could change while are blocked in
  764                  * malloc() is if this semaphore set were destroyed
  765                  * and a new one created with the same index.
  766                  * However, semvalid() will catch that due to the
  767                  * sequence number unless exactly 0x8000 (or a
  768                  * multiple thereof) semaphore sets for the same index
  769                  * are created and destroyed while we are in malloc!
  770                  *
  771                  */
  772                 count = semakptr->u.sem_nsems;
  773                 mtx_unlock(sema_mtxp);              
  774                 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK);
  775                 mtx_lock(sema_mtxp);
  776                 if ((error = semvalid(semid, semakptr)) != 0)
  777                         goto done2;
  778                 KASSERT(count == semakptr->u.sem_nsems, ("nsems changed"));
  779                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  780                         goto done2;
  781                 for (i = 0; i < semakptr->u.sem_nsems; i++)
  782                         array[i] = semakptr->u.sem_base[i].semval;
  783                 mtx_unlock(sema_mtxp);
  784                 error = copyout(array, arg->array, count * sizeof(*array));
  785                 mtx_lock(sema_mtxp);
  786                 break;
  787 
  788         case GETZCNT:
  789                 if ((error = semvalid(semid, semakptr)) != 0)
  790                         goto done2;
  791                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  792                         goto done2;
  793                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  794                         error = EINVAL;
  795                         goto done2;
  796                 }
  797                 *rval = semakptr->u.sem_base[semnum].semzcnt;
  798                 break;
  799 
  800         case SETVAL:
  801                 if ((error = semvalid(semid, semakptr)) != 0)
  802                         goto done2;
  803                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
  804                         goto done2;
  805                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  806                         error = EINVAL;
  807                         goto done2;
  808                 }
  809                 if (arg->val < 0 || arg->val > seminfo.semvmx) {
  810                         error = ERANGE;
  811                         goto done2;
  812                 }
  813                 semakptr->u.sem_base[semnum].semval = arg->val;
  814                 SEMUNDO_LOCK();
  815                 semundo_clear(semidx, semnum);
  816                 SEMUNDO_UNLOCK();
  817                 wakeup(semakptr);
  818                 break;
  819 
  820         case SETALL:
  821                 /*
  822                  * See comment on GETALL for why 'count' shouldn't change
  823                  * and why we require a userland buffer.
  824                  */
  825                 count = semakptr->u.sem_nsems;
  826                 mtx_unlock(sema_mtxp);              
  827                 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK);
  828                 error = copyin(arg->array, array, count * sizeof(*array));
  829                 mtx_lock(sema_mtxp);
  830                 if (error)
  831                         break;
  832                 if ((error = semvalid(semid, semakptr)) != 0)
  833                         goto done2;
  834                 KASSERT(count == semakptr->u.sem_nsems, ("nsems changed"));
  835                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
  836                         goto done2;
  837                 for (i = 0; i < semakptr->u.sem_nsems; i++) {
  838                         usval = array[i];
  839                         if (usval > seminfo.semvmx) {
  840                                 error = ERANGE;
  841                                 break;
  842                         }
  843                         semakptr->u.sem_base[i].semval = usval;
  844                 }
  845                 SEMUNDO_LOCK();
  846                 semundo_clear(semidx, -1);
  847                 SEMUNDO_UNLOCK();
  848                 wakeup(semakptr);
  849                 break;
  850 
  851         default:
  852                 error = EINVAL;
  853                 break;
  854         }
  855 
  856 done2:
  857         mtx_unlock(sema_mtxp);
  858         if (array != NULL)
  859                 free(array, M_TEMP);
  860         return(error);
  861 }
  862 
  863 #ifndef _SYS_SYSPROTO_H_
  864 struct semget_args {
  865         key_t   key;
  866         int     nsems;
  867         int     semflg;
  868 };
  869 #endif
  870 int
  871 semget(td, uap)
  872         struct thread *td;
  873         struct semget_args *uap;
  874 {
  875         int semid, error = 0;
  876         int key = uap->key;
  877         int nsems = uap->nsems;
  878         int semflg = uap->semflg;
  879         struct ucred *cred = td->td_ucred;
  880 
  881         DPRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));
  882         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
  883                 return (ENOSYS);
  884 
  885         mtx_lock(&Giant);
  886         if (key != IPC_PRIVATE) {
  887                 for (semid = 0; semid < seminfo.semmni; semid++) {
  888                         if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) &&
  889                             sema[semid].u.sem_perm.key == key)
  890                                 break;
  891                 }
  892                 if (semid < seminfo.semmni) {
  893                         DPRINTF(("found public key\n"));
  894                         if ((error = ipcperm(td, &sema[semid].u.sem_perm,
  895                             semflg & 0700))) {
  896                                 goto done2;
  897                         }
  898                         if (nsems > 0 && sema[semid].u.sem_nsems < nsems) {
  899                                 DPRINTF(("too small\n"));
  900                                 error = EINVAL;
  901                                 goto done2;
  902                         }
  903                         if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
  904                                 DPRINTF(("not exclusive\n"));
  905                                 error = EEXIST;
  906                                 goto done2;
  907                         }
  908 #ifdef MAC
  909                         error = mac_check_sysv_semget(cred, &sema[semid]);
  910                         if (error != 0)
  911                                 goto done2;
  912 #endif
  913                         goto found;
  914                 }
  915         }
  916 
  917         DPRINTF(("need to allocate the semid_kernel\n"));
  918         if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
  919                 if (nsems <= 0 || nsems > seminfo.semmsl) {
  920                         DPRINTF(("nsems out of range (0<%d<=%d)\n", nsems,
  921                             seminfo.semmsl));
  922                         error = EINVAL;
  923                         goto done2;
  924                 }
  925                 if (nsems > seminfo.semmns - semtot) {
  926                         DPRINTF((
  927                             "not enough semaphores left (need %d, got %d)\n",
  928                             nsems, seminfo.semmns - semtot));
  929                         error = ENOSPC;
  930                         goto done2;
  931                 }
  932                 for (semid = 0; semid < seminfo.semmni; semid++) {
  933                         if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0)
  934                                 break;
  935                 }
  936                 if (semid == seminfo.semmni) {
  937                         DPRINTF(("no more semid_kernel's available\n"));
  938                         error = ENOSPC;
  939                         goto done2;
  940                 }
  941                 DPRINTF(("semid %d is available\n", semid));
  942                 sema[semid].u.sem_perm.key = key;
  943                 sema[semid].u.sem_perm.cuid = cred->cr_uid;
  944                 sema[semid].u.sem_perm.uid = cred->cr_uid;
  945                 sema[semid].u.sem_perm.cgid = cred->cr_gid;
  946                 sema[semid].u.sem_perm.gid = cred->cr_gid;
  947                 sema[semid].u.sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
  948                 sema[semid].u.sem_perm.seq =
  949                     (sema[semid].u.sem_perm.seq + 1) & 0x7fff;
  950                 sema[semid].u.sem_nsems = nsems;
  951                 sema[semid].u.sem_otime = 0;
  952                 sema[semid].u.sem_ctime = time_second;
  953                 sema[semid].u.sem_base = &sem[semtot];
  954                 semtot += nsems;
  955                 bzero(sema[semid].u.sem_base,
  956                     sizeof(sema[semid].u.sem_base[0])*nsems);
  957 #ifdef MAC
  958                 mac_create_sysv_sem(cred, &sema[semid]);
  959 #endif
  960                 DPRINTF(("sembase = %p, next = %p\n",
  961                     sema[semid].u.sem_base, &sem[semtot]));
  962         } else {
  963                 DPRINTF(("didn't find it and wasn't asked to create it\n"));
  964                 error = ENOENT;
  965                 goto done2;
  966         }
  967 
  968 found:
  969         td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].u.sem_perm);
  970 done2:
  971         mtx_unlock(&Giant);
  972         return (error);
  973 }
  974 
  975 #ifndef _SYS_SYSPROTO_H_
  976 struct semop_args {
  977         int     semid;
  978         struct  sembuf *sops;
  979         size_t  nsops;
  980 };
  981 #endif
  982 int
  983 semop(td, uap)
  984         struct thread *td;
  985         struct semop_args *uap;
  986 {
  987 #define SMALL_SOPS      8
  988         struct sembuf small_sops[SMALL_SOPS];
  989         int semid = uap->semid;
  990         size_t nsops = uap->nsops;
  991         struct sembuf *sops;
  992         struct semid_kernel *semakptr;
  993         struct sembuf *sopptr = 0;
  994         struct sem *semptr = 0;
  995         struct sem_undo *suptr;
  996         struct mtx *sema_mtxp;
  997         size_t i, j, k;
  998         int error;
  999         int do_wakeup, do_undos;
 1000 
 1001 #ifdef SEM_DEBUG
 1002         sops = NULL;
 1003 #endif
 1004         DPRINTF(("call to semop(%d, %p, %u)\n", semid, sops, nsops));
 1005 
 1006         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
 1007                 return (ENOSYS);
 1008 
 1009         semid = IPCID_TO_IX(semid);     /* Convert back to zero origin */
 1010 
 1011         if (semid < 0 || semid >= seminfo.semmni)
 1012                 return (EINVAL);
 1013 
 1014         /* Allocate memory for sem_ops */
 1015         if (nsops <= SMALL_SOPS)
 1016                 sops = small_sops;
 1017         else if (nsops <= seminfo.semopm)
 1018                 sops = malloc(nsops * sizeof(*sops), M_TEMP, M_WAITOK);
 1019         else {
 1020                 DPRINTF(("too many sops (max=%d, nsops=%d)\n", seminfo.semopm,
 1021                     nsops));
 1022                 return (E2BIG);
 1023         }
 1024         if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) {
 1025                 DPRINTF(("error = %d from copyin(%p, %p, %d)\n", error,
 1026                     uap->sops, sops, nsops * sizeof(sops[0])));
 1027                 if (sops != small_sops)
 1028                         free(sops, M_SEM);
 1029                 return (error);
 1030         }
 1031 
 1032         semakptr = &sema[semid];
 1033         sema_mtxp = &sema_mtx[semid];
 1034         mtx_lock(sema_mtxp);
 1035         if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
 1036                 error = EINVAL;
 1037                 goto done2;
 1038         }
 1039         if (semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
 1040                 error = EINVAL;
 1041                 goto done2;
 1042         }
 1043         /*
 1044          * Initial pass thru sops to see what permissions are needed.
 1045          * Also perform any checks that don't need repeating on each
 1046          * attempt to satisfy the request vector.
 1047          */
 1048         j = 0;          /* permission needed */
 1049         do_undos = 0;
 1050         for (i = 0; i < nsops; i++) {
 1051                 sopptr = &sops[i];
 1052                 if (sopptr->sem_num >= semakptr->u.sem_nsems) {
 1053                         error = EFBIG;
 1054                         goto done2;
 1055                 }
 1056                 if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0)
 1057                         do_undos = 1;
 1058                 j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A;
 1059         }
 1060 
 1061         if ((error = ipcperm(td, &semakptr->u.sem_perm, j))) {
 1062                 DPRINTF(("error = %d from ipaccess\n", error));
 1063                 goto done2;
 1064         }
 1065 #ifdef MAC
 1066         error = mac_check_sysv_semop(td->td_ucred, semakptr, j);
 1067         if (error != 0)
 1068                 goto done2;
 1069 #endif
 1070 
 1071         /*
 1072          * Loop trying to satisfy the vector of requests.
 1073          * If we reach a point where we must wait, any requests already
 1074          * performed are rolled back and we go to sleep until some other
 1075          * process wakes us up.  At this point, we start all over again.
 1076          *
 1077          * This ensures that from the perspective of other tasks, a set
 1078          * of requests is atomic (never partially satisfied).
 1079          */
 1080         for (;;) {
 1081                 do_wakeup = 0;
 1082                 error = 0;      /* error return if necessary */
 1083 
 1084                 for (i = 0; i < nsops; i++) {
 1085                         sopptr = &sops[i];
 1086                         semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1087 
 1088                         DPRINTF((
 1089                             "semop:  semakptr=%p, sem_base=%p, "
 1090                             "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n",
 1091                             semakptr, semakptr->u.sem_base, semptr,
 1092                             sopptr->sem_num, semptr->semval, sopptr->sem_op,
 1093                             (sopptr->sem_flg & IPC_NOWAIT) ?
 1094                             "nowait" : "wait"));
 1095 
 1096                         if (sopptr->sem_op < 0) {
 1097                                 if (semptr->semval + sopptr->sem_op < 0) {
 1098                                         DPRINTF(("semop:  can't do it now\n"));
 1099                                         break;
 1100                                 } else {
 1101                                         semptr->semval += sopptr->sem_op;
 1102                                         if (semptr->semval == 0 &&
 1103                                             semptr->semzcnt > 0)
 1104                                                 do_wakeup = 1;
 1105                                 }
 1106                         } else if (sopptr->sem_op == 0) {
 1107                                 if (semptr->semval != 0) {
 1108                                         DPRINTF(("semop:  not zero now\n"));
 1109                                         break;
 1110                                 }
 1111                         } else if (semptr->semval + sopptr->sem_op >
 1112                             seminfo.semvmx) {
 1113                                 error = ERANGE;
 1114                                 break;
 1115                         } else {
 1116                                 if (semptr->semncnt > 0)
 1117                                         do_wakeup = 1;
 1118                                 semptr->semval += sopptr->sem_op;
 1119                         }
 1120                 }
 1121 
 1122                 /*
 1123                  * Did we get through the entire vector?
 1124                  */
 1125                 if (i >= nsops)
 1126                         goto done;
 1127 
 1128                 /*
 1129                  * No ... rollback anything that we've already done
 1130                  */
 1131                 DPRINTF(("semop:  rollback 0 through %d\n", i-1));
 1132                 for (j = 0; j < i; j++)
 1133                         semakptr->u.sem_base[sops[j].sem_num].semval -=
 1134                             sops[j].sem_op;
 1135 
 1136                 /* If we detected an error, return it */
 1137                 if (error != 0)
 1138                         goto done2;
 1139 
 1140                 /*
 1141                  * If the request that we couldn't satisfy has the
 1142                  * NOWAIT flag set then return with EAGAIN.
 1143                  */
 1144                 if (sopptr->sem_flg & IPC_NOWAIT) {
 1145                         error = EAGAIN;
 1146                         goto done2;
 1147                 }
 1148 
 1149                 if (sopptr->sem_op == 0)
 1150                         semptr->semzcnt++;
 1151                 else
 1152                         semptr->semncnt++;
 1153 
 1154                 DPRINTF(("semop:  good night!\n"));
 1155                 error = msleep(semakptr, sema_mtxp, (PZERO - 4) | PCATCH,
 1156                     "semwait", 0);
 1157                 DPRINTF(("semop:  good morning (error=%d)!\n", error));
 1158                 /* return code is checked below, after sem[nz]cnt-- */
 1159 
 1160                 /*
 1161                  * Make sure that the semaphore still exists
 1162                  */
 1163                 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
 1164                     semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
 1165                         error = EIDRM;
 1166                         goto done2;
 1167                 }
 1168 
 1169                 /*
 1170                  * Renew the semaphore's pointer after wakeup since
 1171                  * during msleep sem_base may have been modified and semptr
 1172                  * is not valid any more
 1173                  */
 1174                 semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1175 
 1176                 /*
 1177                  * The semaphore is still alive.  Readjust the count of
 1178                  * waiting processes.
 1179                  */
 1180                 if (sopptr->sem_op == 0)
 1181                         semptr->semzcnt--;
 1182                 else
 1183                         semptr->semncnt--;
 1184 
 1185                 /*
 1186                  * Is it really morning, or was our sleep interrupted?
 1187                  * (Delayed check of msleep() return code because we
 1188                  * need to decrement sem[nz]cnt either way.)
 1189                  */
 1190                 if (error != 0) {
 1191                         error = EINTR;
 1192                         goto done2;
 1193                 }
 1194                 DPRINTF(("semop:  good morning!\n"));
 1195         }
 1196 
 1197 done:
 1198         /*
 1199          * Process any SEM_UNDO requests.
 1200          */
 1201         if (do_undos) {
 1202                 SEMUNDO_LOCK();
 1203                 suptr = NULL;
 1204                 for (i = 0; i < nsops; i++) {
 1205                         /*
 1206                          * We only need to deal with SEM_UNDO's for non-zero
 1207                          * op's.
 1208                          */
 1209                         int adjval;
 1210 
 1211                         if ((sops[i].sem_flg & SEM_UNDO) == 0)
 1212                                 continue;
 1213                         adjval = sops[i].sem_op;
 1214                         if (adjval == 0)
 1215                                 continue;
 1216                         error = semundo_adjust(td, &suptr, semid,
 1217                             sops[i].sem_num, -adjval);
 1218                         if (error == 0)
 1219                                 continue;
 1220 
 1221                         /*
 1222                          * Oh-Oh!  We ran out of either sem_undo's or undo's.
 1223                          * Rollback the adjustments to this point and then
 1224                          * rollback the semaphore ups and down so we can return
 1225                          * with an error with all structures restored.  We
 1226                          * rollback the undo's in the exact reverse order that
 1227                          * we applied them.  This guarantees that we won't run
 1228                          * out of space as we roll things back out.
 1229                          */
 1230                         for (j = 0; j < i; j++) {
 1231                                 k = i - j - 1;
 1232                                 if ((sops[k].sem_flg & SEM_UNDO) == 0)
 1233                                         continue;
 1234                                 adjval = sops[k].sem_op;
 1235                                 if (adjval == 0)
 1236                                         continue;
 1237                                 if (semundo_adjust(td, &suptr, semid,
 1238                                     sops[k].sem_num, adjval) != 0)
 1239                                         panic("semop - can't undo undos");
 1240                         }
 1241 
 1242                         for (j = 0; j < nsops; j++)
 1243                                 semakptr->u.sem_base[sops[j].sem_num].semval -=
 1244                                     sops[j].sem_op;
 1245 
 1246                         DPRINTF(("error = %d from semundo_adjust\n", error));
 1247                         SEMUNDO_UNLOCK();
 1248                         goto done2;
 1249                 } /* loop through the sops */
 1250                 SEMUNDO_UNLOCK();
 1251         } /* if (do_undos) */
 1252 
 1253         /* We're definitely done - set the sempid's and time */
 1254         for (i = 0; i < nsops; i++) {
 1255                 sopptr = &sops[i];
 1256                 semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1257                 semptr->sempid = td->td_proc->p_pid;
 1258         }
 1259         semakptr->u.sem_otime = time_second;
 1260 
 1261         /*
 1262          * Do a wakeup if any semaphore was up'd whilst something was
 1263          * sleeping on it.
 1264          */
 1265         if (do_wakeup) {
 1266                 DPRINTF(("semop:  doing wakeup\n"));
 1267                 wakeup(semakptr);
 1268                 DPRINTF(("semop:  back from wakeup\n"));
 1269         }
 1270         DPRINTF(("semop:  done\n"));
 1271         td->td_retval[0] = 0;
 1272 done2:
 1273         mtx_unlock(sema_mtxp);
 1274         if (sops != small_sops)
 1275                 free(sops, M_SEM);
 1276         return (error);
 1277 }
 1278 
 1279 /*
 1280  * Go through the undo structures for this process and apply the adjustments to
 1281  * semaphores.
 1282  */
 1283 static void
 1284 semexit_myhook(arg, p)
 1285         void *arg;
 1286         struct proc *p;
 1287 {
 1288         struct sem_undo *suptr;
 1289         struct sem_undo **supptr;
 1290 
 1291         /*
 1292          * Go through the chain of undo vectors looking for one
 1293          * associated with this process.
 1294          */
 1295         SEMUNDO_LOCK();
 1296         SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, un_next) {
 1297                 if (suptr->un_proc == p) {
 1298                         *supptr = SLIST_NEXT(suptr, un_next);
 1299                         break;
 1300                 }
 1301         }
 1302         SEMUNDO_UNLOCK();
 1303 
 1304         if (suptr == NULL)
 1305                 return;
 1306 
 1307         DPRINTF(("proc @%p has undo structure with %d entries\n", p,
 1308             suptr->un_cnt));
 1309 
 1310         /*
 1311          * If there are any active undo elements then process them.
 1312          */
 1313         if (suptr->un_cnt > 0) {
 1314                 int ix;
 1315 
 1316                 for (ix = 0; ix < suptr->un_cnt; ix++) {
 1317                         int semid = suptr->un_ent[ix].un_id;
 1318                         int semnum = suptr->un_ent[ix].un_num;
 1319                         int adjval = suptr->un_ent[ix].un_adjval;
 1320                         struct semid_kernel *semakptr;
 1321                         struct mtx *sema_mtxp;
 1322 
 1323                         semakptr = &sema[semid];
 1324                         sema_mtxp = &sema_mtx[semid];
 1325                         mtx_lock(sema_mtxp);
 1326                         SEMUNDO_LOCK();
 1327                         if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0)
 1328                                 panic("semexit - semid not allocated");
 1329                         if (semnum >= semakptr->u.sem_nsems)
 1330                                 panic("semexit - semnum out of range");
 1331 
 1332                         DPRINTF((
 1333                             "semexit:  %p id=%d num=%d(adj=%d) ; sem=%d\n",
 1334                             suptr->un_proc, suptr->un_ent[ix].un_id,
 1335                             suptr->un_ent[ix].un_num,
 1336                             suptr->un_ent[ix].un_adjval,
 1337                             semakptr->u.sem_base[semnum].semval));
 1338 
 1339                         if (adjval < 0) {
 1340                                 if (semakptr->u.sem_base[semnum].semval <
 1341                                     -adjval)
 1342                                         semakptr->u.sem_base[semnum].semval = 0;
 1343                                 else
 1344                                         semakptr->u.sem_base[semnum].semval +=
 1345                                             adjval;
 1346                         } else
 1347                                 semakptr->u.sem_base[semnum].semval += adjval;
 1348 
 1349                         wakeup(semakptr);
 1350                         DPRINTF(("semexit:  back from wakeup\n"));
 1351                         mtx_unlock(sema_mtxp);
 1352                         SEMUNDO_UNLOCK();
 1353                 }
 1354         }
 1355 
 1356         /*
 1357          * Deallocate the undo vector.
 1358          */
 1359         DPRINTF(("removing vector\n"));
 1360         SEMUNDO_LOCK();
 1361         suptr->un_proc = NULL;
 1362         SEMUNDO_UNLOCK();
 1363 }
 1364 
 1365 static int
 1366 sysctl_sema(SYSCTL_HANDLER_ARGS)
 1367 {
 1368 
 1369         return (SYSCTL_OUT(req, sema,
 1370             sizeof(struct semid_kernel) * seminfo.semmni));
 1371 }

Cache object: 6eb0cb3b37cfe1e05f0fdc920fa2ba7f


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