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


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

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

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    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: releng/6.3/sys/kern/sysv_sem.c 173886 2007-11-24 19:45:58Z cvs2svn $");
   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/sysent.h>
   57 #include <sys/sysctl.h>
   58 #include <sys/malloc.h>
   59 #include <sys/jail.h>
   60 #include <sys/mac.h>
   61 
   62 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
   63 
   64 #ifdef SEM_DEBUG
   65 #define DPRINTF(a)      printf a
   66 #else
   67 #define DPRINTF(a)
   68 #endif
   69 #ifdef MAC_DEBUG
   70 #define MPRINTF(a)      printf a
   71 #else
   72 #define MPRINTF(a)
   73 #endif
   74 
   75 static void seminit(void);
   76 static int sysvsem_modload(struct module *, int, void *);
   77 static int semunload(void);
   78 static void semexit_myhook(void *arg, struct proc *p);
   79 static int sysctl_sema(SYSCTL_HANDLER_ARGS);
   80 static int semvalid(int semid, struct semid_kernel *semakptr);
   81 
   82 #ifndef _SYS_SYSPROTO_H_
   83 struct __semctl_args;
   84 int __semctl(struct thread *td, struct __semctl_args *uap);
   85 struct semget_args;
   86 int semget(struct thread *td, struct semget_args *uap);
   87 struct semop_args;
   88 int semop(struct thread *td, struct semop_args *uap);
   89 #endif
   90 
   91 static struct sem_undo *semu_alloc(struct thread *td);
   92 static int semundo_adjust(struct thread *td, struct sem_undo **supptr,
   93                 int semid, int semnum, int adjval);
   94 static void semundo_clear(int semid, int semnum);
   95 
   96 /* XXX casting to (sy_call_t *) is bogus, as usual. */
   97 static sy_call_t *semcalls[] = {
   98         (sy_call_t *)__semctl, (sy_call_t *)semget,
   99         (sy_call_t *)semop
  100 };
  101 
  102 static struct mtx       sem_mtx;        /* semaphore global lock */
  103 static int      semtot = 0;
  104 static struct semid_kernel *sema;       /* semaphore id pool */
  105 static struct mtx *sema_mtx;    /* semaphore id pool mutexes*/
  106 static struct sem *sem;         /* semaphore pool */
  107 SLIST_HEAD(, sem_undo) semu_list;       /* list of active undo structures */
  108 static int      *semu;          /* undo structure pool */
  109 static eventhandler_tag semexit_tag;
  110 
  111 #define SEMUNDO_MTX             sem_mtx
  112 #define SEMUNDO_LOCK()          mtx_lock(&SEMUNDO_MTX);
  113 #define SEMUNDO_UNLOCK()        mtx_unlock(&SEMUNDO_MTX);
  114 #define SEMUNDO_LOCKASSERT(how) mtx_assert(&SEMUNDO_MTX, (how));
  115 
  116 struct sem {
  117         u_short semval;         /* semaphore value */
  118         pid_t   sempid;         /* pid of last operation */
  119         u_short semncnt;        /* # awaiting semval > cval */
  120         u_short semzcnt;        /* # awaiting semval = 0 */
  121 };
  122 
  123 /*
  124  * Undo structure (one per process)
  125  */
  126 struct sem_undo {
  127         SLIST_ENTRY(sem_undo) un_next;  /* ptr to next active undo structure */
  128         struct  proc *un_proc;          /* owner of this structure */
  129         short   un_cnt;                 /* # of active entries */
  130         struct undo {
  131                 short   un_adjval;      /* adjust on exit values */
  132                 short   un_num;         /* semaphore # */
  133                 int     un_id;          /* semid */
  134         } un_ent[1];                    /* undo entries */
  135 };
  136 
  137 /*
  138  * Configuration parameters
  139  */
  140 #ifndef SEMMNI
  141 #define SEMMNI  10              /* # of semaphore identifiers */
  142 #endif
  143 #ifndef SEMMNS
  144 #define SEMMNS  60              /* # of semaphores in system */
  145 #endif
  146 #ifndef SEMUME
  147 #define SEMUME  10              /* max # of undo entries per process */
  148 #endif
  149 #ifndef SEMMNU
  150 #define SEMMNU  30              /* # of undo structures in system */
  151 #endif
  152 
  153 /* shouldn't need tuning */
  154 #ifndef SEMMAP
  155 #define SEMMAP  30              /* # of entries in semaphore map */
  156 #endif
  157 #ifndef SEMMSL
  158 #define SEMMSL  SEMMNS          /* max # of semaphores per id */
  159 #endif
  160 #ifndef SEMOPM
  161 #define SEMOPM  100             /* max # of operations per semop call */
  162 #endif
  163 
  164 #define SEMVMX  32767           /* semaphore maximum value */
  165 #define SEMAEM  16384           /* adjust on exit max value */
  166 
  167 /*
  168  * Due to the way semaphore memory is allocated, we have to ensure that
  169  * SEMUSZ is properly aligned.
  170  */
  171 
  172 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
  173 
  174 /* actual size of an undo structure */
  175 #define SEMUSZ  SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
  176 
  177 /*
  178  * Macro to find a particular sem_undo vector
  179  */
  180 #define SEMU(ix) \
  181         ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
  182 
  183 /*
  184  * semaphore info struct
  185  */
  186 struct seminfo seminfo = {
  187                 SEMMAP,         /* # of entries in semaphore map */
  188                 SEMMNI,         /* # of semaphore identifiers */
  189                 SEMMNS,         /* # of semaphores in system */
  190                 SEMMNU,         /* # of undo structures in system */
  191                 SEMMSL,         /* max # of semaphores per id */
  192                 SEMOPM,         /* max # of operations per semop call */
  193                 SEMUME,         /* max # of undo entries per process */
  194                 SEMUSZ,         /* size in bytes of undo structure */
  195                 SEMVMX,         /* semaphore maximum value */
  196                 SEMAEM          /* adjust on exit max value */
  197 };
  198 
  199 SYSCTL_DECL(_kern_ipc);
  200 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0,
  201     "Number of entries in the semaphore map");
  202 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RDTUN, &seminfo.semmni, 0,
  203     "Number of semaphore identifiers");
  204 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RDTUN, &seminfo.semmns, 0,
  205     "Maximum number of semaphores in the system");
  206 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RDTUN, &seminfo.semmnu, 0,
  207     "Maximum number of undo structures in the system");
  208 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0,
  209     "Max semaphores per id");
  210 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RDTUN, &seminfo.semopm, 0,
  211     "Max operations per semop call");
  212 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RDTUN, &seminfo.semume, 0,
  213     "Max undo entries per process");
  214 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RDTUN, &seminfo.semusz, 0,
  215     "Size in bytes of undo structure");
  216 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0,
  217     "Semaphore maximum value");
  218 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0,
  219     "Adjust on exit max value");
  220 SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLFLAG_RD,
  221     NULL, 0, sysctl_sema, "", "");
  222 
  223 static void
  224 seminit(void)
  225 {
  226         int i;
  227 
  228         TUNABLE_INT_FETCH("kern.ipc.semmap", &seminfo.semmap);
  229         TUNABLE_INT_FETCH("kern.ipc.semmni", &seminfo.semmni);
  230         TUNABLE_INT_FETCH("kern.ipc.semmns", &seminfo.semmns);
  231         TUNABLE_INT_FETCH("kern.ipc.semmnu", &seminfo.semmnu);
  232         TUNABLE_INT_FETCH("kern.ipc.semmsl", &seminfo.semmsl);
  233         TUNABLE_INT_FETCH("kern.ipc.semopm", &seminfo.semopm);
  234         TUNABLE_INT_FETCH("kern.ipc.semume", &seminfo.semume);
  235         TUNABLE_INT_FETCH("kern.ipc.semusz", &seminfo.semusz);
  236         TUNABLE_INT_FETCH("kern.ipc.semvmx", &seminfo.semvmx);
  237         TUNABLE_INT_FETCH("kern.ipc.semaem", &seminfo.semaem);
  238 
  239         sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
  240         sema = malloc(sizeof(struct semid_kernel) * seminfo.semmni, M_SEM,
  241             M_WAITOK);
  242         sema_mtx = malloc(sizeof(struct mtx) * seminfo.semmni, M_SEM,
  243             M_WAITOK | M_ZERO);
  244         semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
  245 
  246         for (i = 0; i < seminfo.semmni; i++) {
  247                 sema[i].u.sem_base = 0;
  248                 sema[i].u.sem_perm.mode = 0;
  249                 sema[i].u.sem_perm.seq = 0;
  250 #ifdef MAC
  251                 mac_init_sysv_sem(&sema[i]);
  252 #endif
  253         }
  254         for (i = 0; i < seminfo.semmni; i++)
  255                 mtx_init(&sema_mtx[i], "semid", NULL, MTX_DEF);
  256         for (i = 0; i < seminfo.semmnu; i++) {
  257                 struct sem_undo *suptr = SEMU(i);
  258                 suptr->un_proc = NULL;
  259         }
  260         SLIST_INIT(&semu_list);
  261         mtx_init(&sem_mtx, "sem", NULL, MTX_DEF);
  262         semexit_tag = EVENTHANDLER_REGISTER(process_exit, semexit_myhook, NULL,
  263             EVENTHANDLER_PRI_ANY);
  264 }
  265 
  266 static int
  267 semunload(void)
  268 {
  269         int i;
  270 
  271         if (semtot != 0)
  272                 return (EBUSY);
  273 
  274         EVENTHANDLER_DEREGISTER(process_exit, semexit_tag);
  275 #ifdef MAC
  276         for (i = 0; i < seminfo.semmni; i++)
  277                 mac_destroy_sysv_sem(&sema[i]);
  278 #endif
  279         free(sem, M_SEM);
  280         free(sema, M_SEM);
  281         free(semu, M_SEM);
  282         for (i = 0; i < seminfo.semmni; i++)
  283                 mtx_destroy(&sema_mtx[i]);
  284         mtx_destroy(&sem_mtx);
  285         return (0);
  286 }
  287 
  288 static int
  289 sysvsem_modload(struct module *module, int cmd, void *arg)
  290 {
  291         int error = 0;
  292 
  293         switch (cmd) {
  294         case MOD_LOAD:
  295                 seminit();
  296                 break;
  297         case MOD_UNLOAD:
  298                 error = semunload();
  299                 break;
  300         case MOD_SHUTDOWN:
  301                 break;
  302         default:
  303                 error = EINVAL;
  304                 break;
  305         }
  306         return (error);
  307 }
  308 
  309 static moduledata_t sysvsem_mod = {
  310         "sysvsem",
  311         &sysvsem_modload,
  312         NULL
  313 };
  314 
  315 SYSCALL_MODULE_HELPER(semsys);
  316 SYSCALL_MODULE_HELPER(__semctl);
  317 SYSCALL_MODULE_HELPER(semget);
  318 SYSCALL_MODULE_HELPER(semop);
  319 
  320 DECLARE_MODULE(sysvsem, sysvsem_mod,
  321         SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
  322 MODULE_VERSION(sysvsem, 1);
  323 
  324 /*
  325  * Entry point for all SEM calls
  326  *
  327  * MPSAFE
  328  */
  329 int
  330 semsys(td, uap)
  331         struct thread *td;
  332         /* XXX actually varargs. */
  333         struct semsys_args /* {
  334                 int     which;
  335                 int     a2;
  336                 int     a3;
  337                 int     a4;
  338                 int     a5;
  339         } */ *uap;
  340 {
  341         int error;
  342 
  343         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
  344                 return (ENOSYS);
  345         if (uap->which < 0 ||
  346             uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
  347                 return (EINVAL);
  348         error = (*semcalls[uap->which])(td, &uap->a2);
  349         return (error);
  350 }
  351 
  352 /*
  353  * Allocate a new sem_undo structure for a process
  354  * (returns ptr to structure or NULL if no more room)
  355  */
  356 
  357 static struct sem_undo *
  358 semu_alloc(td)
  359         struct thread *td;
  360 {
  361         int i;
  362         struct sem_undo *suptr;
  363         struct sem_undo **supptr;
  364         int attempt;
  365 
  366         SEMUNDO_LOCKASSERT(MA_OWNED);
  367         /*
  368          * Try twice to allocate something.
  369          * (we'll purge an empty structure after the first pass so
  370          * two passes are always enough)
  371          */
  372 
  373         for (attempt = 0; attempt < 2; attempt++) {
  374                 /*
  375                  * Look for a free structure.
  376                  * Fill it in and return it if we find one.
  377                  */
  378 
  379                 for (i = 0; i < seminfo.semmnu; i++) {
  380                         suptr = SEMU(i);
  381                         if (suptr->un_proc == NULL) {
  382                                 SLIST_INSERT_HEAD(&semu_list, suptr, un_next);
  383                                 suptr->un_cnt = 0;
  384                                 suptr->un_proc = td->td_proc;
  385                                 return(suptr);
  386                         }
  387                 }
  388 
  389                 /*
  390                  * We didn't find a free one, if this is the first attempt
  391                  * then try to free a structure.
  392                  */
  393 
  394                 if (attempt == 0) {
  395                         /* All the structures are in use - try to free one */
  396                         int did_something = 0;
  397 
  398                         SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list,
  399                             un_next) {
  400                                 if (suptr->un_cnt == 0) {
  401                                         suptr->un_proc = NULL;
  402                                         did_something = 1;
  403                                         *supptr = SLIST_NEXT(suptr, un_next);
  404                                         break;
  405                                 }
  406                         }
  407 
  408                         /* If we didn't free anything then just give-up */
  409                         if (!did_something)
  410                                 return(NULL);
  411                 } else {
  412                         /*
  413                          * The second pass failed even though we freed
  414                          * something after the first pass!
  415                          * This is IMPOSSIBLE!
  416                          */
  417                         panic("semu_alloc - second attempt failed");
  418                 }
  419         }
  420         return (NULL);
  421 }
  422 
  423 /*
  424  * Adjust a particular entry for a particular proc
  425  */
  426 
  427 static int
  428 semundo_adjust(td, supptr, semid, semnum, adjval)
  429         struct thread *td;
  430         struct sem_undo **supptr;
  431         int semid, semnum;
  432         int adjval;
  433 {
  434         struct proc *p = td->td_proc;
  435         struct sem_undo *suptr;
  436         struct undo *sunptr;
  437         int i;
  438 
  439         SEMUNDO_LOCKASSERT(MA_OWNED);
  440         /* Look for and remember the sem_undo if the caller doesn't provide
  441            it */
  442 
  443         suptr = *supptr;
  444         if (suptr == NULL) {
  445                 SLIST_FOREACH(suptr, &semu_list, un_next) {
  446                         if (suptr->un_proc == p) {
  447                                 *supptr = suptr;
  448                                 break;
  449                         }
  450                 }
  451                 if (suptr == NULL) {
  452                         if (adjval == 0)
  453                                 return(0);
  454                         suptr = semu_alloc(td);
  455                         if (suptr == NULL)
  456                                 return(ENOSPC);
  457                         *supptr = suptr;
  458                 }
  459         }
  460 
  461         /*
  462          * Look for the requested entry and adjust it (delete if adjval becomes
  463          * 0).
  464          */
  465         sunptr = &suptr->un_ent[0];
  466         for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
  467                 if (sunptr->un_id != semid || sunptr->un_num != semnum)
  468                         continue;
  469                 if (adjval != 0) {
  470                         adjval += sunptr->un_adjval;
  471                         if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
  472                                 return (ERANGE);
  473                 }
  474                 sunptr->un_adjval = adjval;
  475                 if (sunptr->un_adjval == 0) {
  476                         suptr->un_cnt--;
  477                         if (i < suptr->un_cnt)
  478                                 suptr->un_ent[i] =
  479                                     suptr->un_ent[suptr->un_cnt];
  480                 }
  481                 return(0);
  482         }
  483 
  484         /* Didn't find the right entry - create it */
  485         if (adjval == 0)
  486                 return(0);
  487         if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
  488                 return (ERANGE);
  489         if (suptr->un_cnt != seminfo.semume) {
  490                 sunptr = &suptr->un_ent[suptr->un_cnt];
  491                 suptr->un_cnt++;
  492                 sunptr->un_adjval = adjval;
  493                 sunptr->un_id = semid; sunptr->un_num = semnum;
  494         } else
  495                 return(EINVAL);
  496         return(0);
  497 }
  498 
  499 static void
  500 semundo_clear(semid, semnum)
  501         int semid, semnum;
  502 {
  503         struct sem_undo *suptr;
  504 
  505         SEMUNDO_LOCKASSERT(MA_OWNED);
  506         SLIST_FOREACH(suptr, &semu_list, un_next) {
  507                 struct undo *sunptr = &suptr->un_ent[0];
  508                 int i = 0;
  509 
  510                 while (i < suptr->un_cnt) {
  511                         if (sunptr->un_id == semid) {
  512                                 if (semnum == -1 || sunptr->un_num == semnum) {
  513                                         suptr->un_cnt--;
  514                                         if (i < suptr->un_cnt) {
  515                                                 suptr->un_ent[i] =
  516                                                   suptr->un_ent[suptr->un_cnt];
  517                                                 continue;
  518                                         }
  519                                 }
  520                                 if (semnum != -1)
  521                                         break;
  522                         }
  523                         i++, sunptr++;
  524                 }
  525         }
  526 }
  527 
  528 static int
  529 semvalid(semid, semakptr)
  530         int semid;
  531         struct semid_kernel *semakptr;
  532 {
  533 
  534         return ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
  535             semakptr->u.sem_perm.seq != IPCID_TO_SEQ(semid) ? EINVAL : 0);
  536 }
  537 
  538 /*
  539  * Note that the user-mode half of this passes a union, not a pointer
  540  */
  541 #ifndef _SYS_SYSPROTO_H_
  542 struct __semctl_args {
  543         int     semid;
  544         int     semnum;
  545         int     cmd;
  546         union   semun *arg;
  547 };
  548 #endif
  549 
  550 /*
  551  * MPSAFE
  552  */
  553 int
  554 __semctl(td, uap)
  555         struct thread *td;
  556         struct __semctl_args *uap;
  557 {
  558         int semid = uap->semid;
  559         int semnum = uap->semnum;
  560         int cmd = uap->cmd;
  561         u_short *array;
  562         union semun *arg = uap->arg;
  563         union semun real_arg;
  564         struct ucred *cred = td->td_ucred;
  565         int i, rval, error;
  566         struct semid_ds sbuf;
  567         struct semid_kernel *semakptr;
  568         struct mtx *sema_mtxp;
  569         u_short usval, count;
  570 
  571         DPRINTF(("call to semctl(%d, %d, %d, 0x%x)\n",
  572             semid, semnum, cmd, arg));
  573         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
  574                 return (ENOSYS);
  575 
  576         array = NULL;
  577 
  578         switch(cmd) {
  579         case SEM_STAT:
  580                 if (semid < 0 || semid >= seminfo.semmni)
  581                         return (EINVAL);
  582                 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
  583                         return (error);
  584                 semakptr = &sema[semid];
  585                 sema_mtxp = &sema_mtx[semid];
  586                 mtx_lock(sema_mtxp);
  587                 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
  588                         error = EINVAL;
  589                         goto done2;
  590                 }
  591                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  592                         goto done2;
  593 #ifdef MAC
  594                 error = mac_check_sysv_semctl(cred, semakptr, cmd);
  595                 if (error != 0) {
  596                         MPRINTF(("mac_check_sysv_semctl returned %d\n",
  597                             error));
  598                         goto done2;
  599                 }
  600 #endif
  601                 mtx_unlock(sema_mtxp);
  602                 error = copyout(&semakptr->u, real_arg.buf,
  603                     sizeof(struct semid_ds));
  604                 rval = IXSEQ_TO_IPCID(semid, semakptr->u.sem_perm);
  605                 if (error == 0)
  606                         td->td_retval[0] = rval;
  607                 return (error);
  608         }
  609 
  610         semid = IPCID_TO_IX(semid);
  611         if (semid < 0 || semid >= seminfo.semmni)
  612                 return (EINVAL);
  613 
  614         semakptr = &sema[semid];
  615         sema_mtxp = &sema_mtx[semid];
  616 #ifdef MAC
  617         mtx_lock(sema_mtxp);
  618         error = mac_check_sysv_semctl(cred, semakptr, cmd);
  619         if (error != 0) {
  620                 MPRINTF(("mac_check_sysv_semctl returned %d\n", error));
  621                 mtx_unlock(sema_mtxp);
  622                 return (error);
  623         }
  624         mtx_unlock(sema_mtxp);
  625 #endif
  626 
  627         error = 0;
  628         rval = 0;
  629 
  630         switch (cmd) {
  631         case IPC_RMID:
  632                 mtx_lock(sema_mtxp);
  633                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  634                         goto done2;
  635                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
  636                         goto done2;
  637                 semakptr->u.sem_perm.cuid = cred->cr_uid;
  638                 semakptr->u.sem_perm.uid = cred->cr_uid;
  639                 semtot -= semakptr->u.sem_nsems;
  640                 for (i = semakptr->u.sem_base - sem; i < semtot; i++)
  641                         sem[i] = sem[i + semakptr->u.sem_nsems];
  642                 for (i = 0; i < seminfo.semmni; i++) {
  643                         if ((sema[i].u.sem_perm.mode & SEM_ALLOC) &&
  644                             sema[i].u.sem_base > semakptr->u.sem_base)
  645                                 sema[i].u.sem_base -= semakptr->u.sem_nsems;
  646                 }
  647                 semakptr->u.sem_perm.mode = 0;
  648 #ifdef MAC
  649                 mac_cleanup_sysv_sem(semakptr);
  650 #endif
  651                 SEMUNDO_LOCK();
  652                 semundo_clear(semid, -1);
  653                 SEMUNDO_UNLOCK();
  654                 wakeup(semakptr);
  655                 break;
  656 
  657         case IPC_SET:
  658                 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
  659                         goto done2;
  660                 if ((error = copyin(real_arg.buf, &sbuf, sizeof(sbuf))) != 0)
  661                         goto done2;
  662                 mtx_lock(sema_mtxp);
  663                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  664                         goto done2;
  665                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
  666                         goto done2;
  667                 semakptr->u.sem_perm.uid = sbuf.sem_perm.uid;
  668                 semakptr->u.sem_perm.gid = sbuf.sem_perm.gid;
  669                 semakptr->u.sem_perm.mode = (semakptr->u.sem_perm.mode &
  670                     ~0777) | (sbuf.sem_perm.mode & 0777);
  671                 semakptr->u.sem_ctime = time_second;
  672                 break;
  673 
  674         case IPC_STAT:
  675                 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
  676                         goto done2;
  677                 mtx_lock(sema_mtxp);
  678                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  679                         goto done2;
  680                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  681                         goto done2;
  682                 sbuf = semakptr->u;
  683                 mtx_unlock(sema_mtxp);
  684                 error = copyout(&semakptr->u, real_arg.buf,
  685                                 sizeof(struct semid_ds));
  686                 break;
  687 
  688         case GETNCNT:
  689                 mtx_lock(sema_mtxp);
  690                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  691                         goto done2;
  692                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  693                         goto done2;
  694                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  695                         error = EINVAL;
  696                         goto done2;
  697                 }
  698                 rval = semakptr->u.sem_base[semnum].semncnt;
  699                 break;
  700 
  701         case GETPID:
  702                 mtx_lock(sema_mtxp);
  703                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  704                         goto done2;
  705                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  706                         goto done2;
  707                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  708                         error = EINVAL;
  709                         goto done2;
  710                 }
  711                 rval = semakptr->u.sem_base[semnum].sempid;
  712                 break;
  713 
  714         case GETVAL:
  715                 mtx_lock(sema_mtxp);
  716                 if ((error = semvalid(uap->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].semval;
  725                 break;
  726 
  727         case GETALL:
  728                 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
  729                         goto done2;
  730                 array = malloc(sizeof(*array) * semakptr->u.sem_nsems, M_TEMP,
  731                     M_WAITOK);
  732                 mtx_lock(sema_mtxp);
  733                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  734                         goto done2;
  735                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  736                         goto done2;
  737                 for (i = 0; i < semakptr->u.sem_nsems; i++)
  738                         array[i] = semakptr->u.sem_base[i].semval;
  739                 mtx_unlock(sema_mtxp);
  740                 error = copyout(array, real_arg.array,
  741                     i * sizeof(real_arg.array[0]));
  742                 break;
  743 
  744         case GETZCNT:
  745                 mtx_lock(sema_mtxp);
  746                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  747                         goto done2;
  748                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  749                         goto done2;
  750                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  751                         error = EINVAL;
  752                         goto done2;
  753                 }
  754                 rval = semakptr->u.sem_base[semnum].semzcnt;
  755                 break;
  756 
  757         case SETVAL:
  758                 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
  759                         goto done2;
  760                 mtx_lock(sema_mtxp);
  761                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  762                         goto done2;
  763                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
  764                         goto done2;
  765                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  766                         error = EINVAL;
  767                         goto done2;
  768                 }
  769                 if (real_arg.val < 0 || real_arg.val > seminfo.semvmx) {
  770                         error = ERANGE;
  771                         goto done2;
  772                 }
  773                 semakptr->u.sem_base[semnum].semval = real_arg.val;
  774                 SEMUNDO_LOCK();
  775                 semundo_clear(semid, semnum);
  776                 SEMUNDO_UNLOCK();
  777                 wakeup(semakptr);
  778                 break;
  779 
  780         case SETALL:
  781                 mtx_lock(sema_mtxp);
  782 raced:
  783                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  784                         goto done2;
  785                 count = semakptr->u.sem_nsems;
  786                 mtx_unlock(sema_mtxp);
  787                 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
  788                         goto done2;
  789                 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK);
  790                 error = copyin(real_arg.array, array, count * sizeof(*array));
  791                 if (error)
  792                         break;
  793                 mtx_lock(sema_mtxp);
  794                 if ((error = semvalid(uap->semid, semakptr)) != 0)
  795                         goto done2;
  796                 /* we could have raced? */
  797                 if (count != semakptr->u.sem_nsems) {
  798                         free(array, M_TEMP);
  799                         array = NULL;
  800                         goto raced;
  801                 }
  802                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
  803                         goto done2;
  804                 for (i = 0; i < semakptr->u.sem_nsems; i++) {
  805                         usval = array[i];
  806                         if (usval > seminfo.semvmx) {
  807                                 error = ERANGE;
  808                                 break;
  809                         }
  810                         semakptr->u.sem_base[i].semval = usval;
  811                 }
  812                 SEMUNDO_LOCK();
  813                 semundo_clear(semid, -1);
  814                 SEMUNDO_UNLOCK();
  815                 wakeup(semakptr);
  816                 break;
  817 
  818         default:
  819                 error = EINVAL;
  820                 break;
  821         }
  822 
  823         if (error == 0)
  824                 td->td_retval[0] = rval;
  825 done2:
  826         if (mtx_owned(sema_mtxp))
  827                 mtx_unlock(sema_mtxp);
  828         if (array != NULL)
  829                 free(array, M_TEMP);
  830         return(error);
  831 }
  832 
  833 #ifndef _SYS_SYSPROTO_H_
  834 struct semget_args {
  835         key_t   key;
  836         int     nsems;
  837         int     semflg;
  838 };
  839 #endif
  840 
  841 /*
  842  * MPSAFE
  843  */
  844 int
  845 semget(td, uap)
  846         struct thread *td;
  847         struct semget_args *uap;
  848 {
  849         int semid, error = 0;
  850         int key = uap->key;
  851         int nsems = uap->nsems;
  852         int semflg = uap->semflg;
  853         struct ucred *cred = td->td_ucred;
  854 
  855         DPRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));
  856         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
  857                 return (ENOSYS);
  858 
  859         mtx_lock(&Giant);
  860         if (key != IPC_PRIVATE) {
  861                 for (semid = 0; semid < seminfo.semmni; semid++) {
  862                         if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) &&
  863                             sema[semid].u.sem_perm.key == key)
  864                                 break;
  865                 }
  866                 if (semid < seminfo.semmni) {
  867                         DPRINTF(("found public key\n"));
  868                         if ((error = ipcperm(td, &sema[semid].u.sem_perm,
  869                             semflg & 0700))) {
  870                                 goto done2;
  871                         }
  872                         if (nsems > 0 && sema[semid].u.sem_nsems < nsems) {
  873                                 DPRINTF(("too small\n"));
  874                                 error = EINVAL;
  875                                 goto done2;
  876                         }
  877                         if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
  878                                 DPRINTF(("not exclusive\n"));
  879                                 error = EEXIST;
  880                                 goto done2;
  881                         }
  882 #ifdef MAC
  883                         error = mac_check_sysv_semget(cred, &sema[semid]);
  884                         if (error != 0) {
  885                                 MPRINTF(("mac_check_sysv_semget returned %d\n",
  886                                     error));
  887                                 goto done2;
  888                         }
  889 #endif
  890                         goto found;
  891                 }
  892         }
  893 
  894         DPRINTF(("need to allocate the semid_kernel\n"));
  895         if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
  896                 if (nsems <= 0 || nsems > seminfo.semmsl) {
  897                         DPRINTF(("nsems out of range (0<%d<=%d)\n", nsems,
  898                             seminfo.semmsl));
  899                         error = EINVAL;
  900                         goto done2;
  901                 }
  902                 if (nsems > seminfo.semmns - semtot) {
  903                         DPRINTF((
  904                             "not enough semaphores left (need %d, got %d)\n",
  905                             nsems, seminfo.semmns - semtot));
  906                         error = ENOSPC;
  907                         goto done2;
  908                 }
  909                 for (semid = 0; semid < seminfo.semmni; semid++) {
  910                         if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0)
  911                                 break;
  912                 }
  913                 if (semid == seminfo.semmni) {
  914                         DPRINTF(("no more semid_kernel's available\n"));
  915                         error = ENOSPC;
  916                         goto done2;
  917                 }
  918                 DPRINTF(("semid %d is available\n", semid));
  919                 sema[semid].u.sem_perm.key = key;
  920                 sema[semid].u.sem_perm.cuid = cred->cr_uid;
  921                 sema[semid].u.sem_perm.uid = cred->cr_uid;
  922                 sema[semid].u.sem_perm.cgid = cred->cr_gid;
  923                 sema[semid].u.sem_perm.gid = cred->cr_gid;
  924                 sema[semid].u.sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
  925                 sema[semid].u.sem_perm.seq =
  926                     (sema[semid].u.sem_perm.seq + 1) & 0x7fff;
  927                 sema[semid].u.sem_nsems = nsems;
  928                 sema[semid].u.sem_otime = 0;
  929                 sema[semid].u.sem_ctime = time_second;
  930                 sema[semid].u.sem_base = &sem[semtot];
  931                 semtot += nsems;
  932                 bzero(sema[semid].u.sem_base,
  933                     sizeof(sema[semid].u.sem_base[0])*nsems);
  934 #ifdef MAC
  935                 mac_create_sysv_sem(cred, &sema[semid]);
  936 #endif
  937                 DPRINTF(("sembase = 0x%x, next = 0x%x\n",
  938                     sema[semid].u.sem_base, &sem[semtot]));
  939         } else {
  940                 DPRINTF(("didn't find it and wasn't asked to create it\n"));
  941                 error = ENOENT;
  942                 goto done2;
  943         }
  944 
  945 found:
  946         td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].u.sem_perm);
  947 done2:
  948         mtx_unlock(&Giant);
  949         return (error);
  950 }
  951 
  952 #ifndef _SYS_SYSPROTO_H_
  953 struct semop_args {
  954         int     semid;
  955         struct  sembuf *sops;
  956         size_t  nsops;
  957 };
  958 #endif
  959 
  960 /*
  961  * MPSAFE
  962  */
  963 int
  964 semop(td, uap)
  965         struct thread *td;
  966         struct semop_args *uap;
  967 {
  968 #define SMALL_SOPS      8
  969         struct sembuf small_sops[SMALL_SOPS];
  970         int semid = uap->semid;
  971         size_t nsops = uap->nsops;
  972         struct sembuf *sops;
  973         struct semid_kernel *semakptr;
  974         struct sembuf *sopptr = 0;
  975         struct sem *semptr = 0;
  976         struct sem_undo *suptr;
  977         struct mtx *sema_mtxp;
  978         size_t i, j, k;
  979         int error;
  980         int do_wakeup, do_undos;
  981 
  982         DPRINTF(("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops));
  983 
  984         if (!jail_sysvipc_allowed && jailed(td->td_ucred))
  985                 return (ENOSYS);
  986 
  987         semid = IPCID_TO_IX(semid);     /* Convert back to zero origin */
  988 
  989         if (semid < 0 || semid >= seminfo.semmni)
  990                 return (EINVAL);
  991 
  992         /* Allocate memory for sem_ops */
  993         if (nsops <= SMALL_SOPS)
  994                 sops = small_sops;
  995         else if (nsops <= seminfo.semopm)
  996                 sops = malloc(nsops * sizeof(*sops), M_TEMP, M_WAITOK);
  997         else {
  998                 DPRINTF(("too many sops (max=%d, nsops=%d)\n", seminfo.semopm,
  999                     nsops));
 1000                 return (E2BIG);
 1001         }
 1002         if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) {
 1003                 DPRINTF(("error = %d from copyin(%08x, %08x, %d)\n", error,
 1004                     uap->sops, sops, nsops * sizeof(sops[0])));
 1005                 if (sops != small_sops)
 1006                         free(sops, M_SEM);
 1007                 return (error);
 1008         }
 1009 
 1010         semakptr = &sema[semid];
 1011         sema_mtxp = &sema_mtx[semid];
 1012         mtx_lock(sema_mtxp);
 1013         if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
 1014                 error = EINVAL;
 1015                 goto done2;
 1016         }
 1017         if (semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
 1018                 error = EINVAL;
 1019                 goto done2;
 1020         }
 1021         /*
 1022          * Initial pass thru sops to see what permissions are needed.
 1023          * Also perform any checks that don't need repeating on each
 1024          * attempt to satisfy the request vector.
 1025          */
 1026         j = 0;          /* permission needed */
 1027         do_undos = 0;
 1028         for (i = 0; i < nsops; i++) {
 1029                 sopptr = &sops[i];
 1030                 if (sopptr->sem_num >= semakptr->u.sem_nsems) {
 1031                         error = EFBIG;
 1032                         goto done2;
 1033                 }
 1034                 if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0)
 1035                         do_undos = 1;
 1036                 j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A;
 1037         }
 1038 
 1039         if ((error = ipcperm(td, &semakptr->u.sem_perm, j))) {
 1040                 DPRINTF(("error = %d from ipaccess\n", error));
 1041                 goto done2;
 1042         }
 1043 #ifdef MAC
 1044         error = mac_check_sysv_semop(td->td_ucred, semakptr, j);
 1045         if (error != 0) {
 1046                 MPRINTF(("mac_check_sysv_semop returned %d\n", error));
 1047                 goto done2;
 1048         }
 1049 #endif
 1050 
 1051         /*
 1052          * Loop trying to satisfy the vector of requests.
 1053          * If we reach a point where we must wait, any requests already
 1054          * performed are rolled back and we go to sleep until some other
 1055          * process wakes us up.  At this point, we start all over again.
 1056          *
 1057          * This ensures that from the perspective of other tasks, a set
 1058          * of requests is atomic (never partially satisfied).
 1059          */
 1060         for (;;) {
 1061                 do_wakeup = 0;
 1062                 error = 0;      /* error return if necessary */
 1063 
 1064                 for (i = 0; i < nsops; i++) {
 1065                         sopptr = &sops[i];
 1066                         semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1067 
 1068                         DPRINTF((
 1069                             "semop:  semakptr=%x, sem_base=%x, "
 1070                             "semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
 1071                             semakptr, semakptr->u.sem_base, semptr,
 1072                             sopptr->sem_num, semptr->semval, sopptr->sem_op,
 1073                             (sopptr->sem_flg & IPC_NOWAIT) ?
 1074                             "nowait" : "wait"));
 1075 
 1076                         if (sopptr->sem_op < 0) {
 1077                                 if (semptr->semval + sopptr->sem_op < 0) {
 1078                                         DPRINTF(("semop:  can't do it now\n"));
 1079                                         break;
 1080                                 } else {
 1081                                         semptr->semval += sopptr->sem_op;
 1082                                         if (semptr->semval == 0 &&
 1083                                             semptr->semzcnt > 0)
 1084                                                 do_wakeup = 1;
 1085                                 }
 1086                         } else if (sopptr->sem_op == 0) {
 1087                                 if (semptr->semval != 0) {
 1088                                         DPRINTF(("semop:  not zero now\n"));
 1089                                         break;
 1090                                 }
 1091                         } else if (semptr->semval + sopptr->sem_op >
 1092                             seminfo.semvmx) {
 1093                                 error = ERANGE;
 1094                                 break;
 1095                         } else {
 1096                                 if (semptr->semncnt > 0)
 1097                                         do_wakeup = 1;
 1098                                 semptr->semval += sopptr->sem_op;
 1099                         }
 1100                 }
 1101 
 1102                 /*
 1103                  * Did we get through the entire vector?
 1104                  */
 1105                 if (i >= nsops)
 1106                         goto done;
 1107 
 1108                 /*
 1109                  * No ... rollback anything that we've already done
 1110                  */
 1111                 DPRINTF(("semop:  rollback 0 through %d\n", i-1));
 1112                 for (j = 0; j < i; j++)
 1113                         semakptr->u.sem_base[sops[j].sem_num].semval -=
 1114                             sops[j].sem_op;
 1115 
 1116                 /* If we detected an error, return it */
 1117                 if (error != 0)
 1118                         goto done2;
 1119 
 1120                 /*
 1121                  * If the request that we couldn't satisfy has the
 1122                  * NOWAIT flag set then return with EAGAIN.
 1123                  */
 1124                 if (sopptr->sem_flg & IPC_NOWAIT) {
 1125                         error = EAGAIN;
 1126                         goto done2;
 1127                 }
 1128 
 1129                 if (sopptr->sem_op == 0)
 1130                         semptr->semzcnt++;
 1131                 else
 1132                         semptr->semncnt++;
 1133 
 1134                 DPRINTF(("semop:  good night!\n"));
 1135                 error = msleep(semakptr, sema_mtxp, (PZERO - 4) | PCATCH,
 1136                     "semwait", 0);
 1137                 DPRINTF(("semop:  good morning (error=%d)!\n", error));
 1138                 /* return code is checked below, after sem[nz]cnt-- */
 1139 
 1140                 /*
 1141                  * Make sure that the semaphore still exists
 1142                  */
 1143                 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
 1144                     semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
 1145                         error = EIDRM;
 1146                         goto done2;
 1147                 }
 1148 
 1149                 /*
 1150                  * The semaphore is still alive.  Readjust the count of
 1151                  * waiting processes.
 1152                  */
 1153                 if (sopptr->sem_op == 0)
 1154                         semptr->semzcnt--;
 1155                 else
 1156                         semptr->semncnt--;
 1157 
 1158                 /*
 1159                  * Is it really morning, or was our sleep interrupted?
 1160                  * (Delayed check of msleep() return code because we
 1161                  * need to decrement sem[nz]cnt either way.)
 1162                  */
 1163                 if (error != 0) {
 1164                         error = EINTR;
 1165                         goto done2;
 1166                 }
 1167                 DPRINTF(("semop:  good morning!\n"));
 1168         }
 1169 
 1170 done:
 1171         /*
 1172          * Process any SEM_UNDO requests.
 1173          */
 1174         if (do_undos) {
 1175                 SEMUNDO_LOCK();
 1176                 suptr = NULL;
 1177                 for (i = 0; i < nsops; i++) {
 1178                         /*
 1179                          * We only need to deal with SEM_UNDO's for non-zero
 1180                          * op's.
 1181                          */
 1182                         int adjval;
 1183 
 1184                         if ((sops[i].sem_flg & SEM_UNDO) == 0)
 1185                                 continue;
 1186                         adjval = sops[i].sem_op;
 1187                         if (adjval == 0)
 1188                                 continue;
 1189                         error = semundo_adjust(td, &suptr, semid,
 1190                             sops[i].sem_num, -adjval);
 1191                         if (error == 0)
 1192                                 continue;
 1193 
 1194                         /*
 1195                          * Oh-Oh!  We ran out of either sem_undo's or undo's.
 1196                          * Rollback the adjustments to this point and then
 1197                          * rollback the semaphore ups and down so we can return
 1198                          * with an error with all structures restored.  We
 1199                          * rollback the undo's in the exact reverse order that
 1200                          * we applied them.  This guarantees that we won't run
 1201                          * out of space as we roll things back out.
 1202                          */
 1203                         for (j = 0; j < i; j++) {
 1204                                 k = i - j - 1;
 1205                                 if ((sops[k].sem_flg & SEM_UNDO) == 0)
 1206                                         continue;
 1207                                 adjval = sops[k].sem_op;
 1208                                 if (adjval == 0)
 1209                                         continue;
 1210                                 if (semundo_adjust(td, &suptr, semid,
 1211                                     sops[k].sem_num, adjval) != 0)
 1212                                         panic("semop - can't undo undos");
 1213                         }
 1214 
 1215                         for (j = 0; j < nsops; j++)
 1216                                 semakptr->u.sem_base[sops[j].sem_num].semval -=
 1217                                     sops[j].sem_op;
 1218 
 1219                         DPRINTF(("error = %d from semundo_adjust\n", error));
 1220                         SEMUNDO_UNLOCK();
 1221                         goto done2;
 1222                 } /* loop through the sops */
 1223                 SEMUNDO_UNLOCK();
 1224         } /* if (do_undos) */
 1225 
 1226         /* We're definitely done - set the sempid's and time */
 1227         for (i = 0; i < nsops; i++) {
 1228                 sopptr = &sops[i];
 1229                 semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1230                 semptr->sempid = td->td_proc->p_pid;
 1231         }
 1232         semakptr->u.sem_otime = time_second;
 1233 
 1234         /*
 1235          * Do a wakeup if any semaphore was up'd whilst something was
 1236          * sleeping on it.
 1237          */
 1238         if (do_wakeup) {
 1239                 DPRINTF(("semop:  doing wakeup\n"));
 1240                 wakeup(semakptr);
 1241                 DPRINTF(("semop:  back from wakeup\n"));
 1242         }
 1243         DPRINTF(("semop:  done\n"));
 1244         td->td_retval[0] = 0;
 1245 done2:
 1246         mtx_unlock(sema_mtxp);
 1247         if (sops != small_sops)
 1248                 free(sops, M_SEM);
 1249         return (error);
 1250 }
 1251 
 1252 /*
 1253  * Go through the undo structures for this process and apply the adjustments to
 1254  * semaphores.
 1255  */
 1256 static void
 1257 semexit_myhook(arg, p)
 1258         void *arg;
 1259         struct proc *p;
 1260 {
 1261         struct sem_undo *suptr;
 1262         struct sem_undo **supptr;
 1263 
 1264         /*
 1265          * Go through the chain of undo vectors looking for one
 1266          * associated with this process.
 1267          */
 1268         SEMUNDO_LOCK();
 1269         SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, un_next) {
 1270                 if (suptr->un_proc == p) {
 1271                         *supptr = SLIST_NEXT(suptr, un_next);
 1272                         break;
 1273                 }
 1274         }
 1275         SEMUNDO_UNLOCK();
 1276 
 1277         if (suptr == NULL)
 1278                 return;
 1279 
 1280         DPRINTF(("proc @%08x has undo structure with %d entries\n", p,
 1281             suptr->un_cnt));
 1282 
 1283         /*
 1284          * If there are any active undo elements then process them.
 1285          */
 1286         if (suptr->un_cnt > 0) {
 1287                 int ix;
 1288 
 1289                 for (ix = 0; ix < suptr->un_cnt; ix++) {
 1290                         int semid = suptr->un_ent[ix].un_id;
 1291                         int semnum = suptr->un_ent[ix].un_num;
 1292                         int adjval = suptr->un_ent[ix].un_adjval;
 1293                         struct semid_kernel *semakptr;
 1294                         struct mtx *sema_mtxp;
 1295 
 1296                         semakptr = &sema[semid];
 1297                         sema_mtxp = &sema_mtx[semid];
 1298                         mtx_lock(sema_mtxp);
 1299                         SEMUNDO_LOCK();
 1300                         if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0)
 1301                                 panic("semexit - semid not allocated");
 1302                         if (semnum >= semakptr->u.sem_nsems)
 1303                                 panic("semexit - semnum out of range");
 1304 
 1305                         DPRINTF((
 1306                             "semexit:  %08x id=%d num=%d(adj=%d) ; sem=%d\n",
 1307                             suptr->un_proc, suptr->un_ent[ix].un_id,
 1308                             suptr->un_ent[ix].un_num,
 1309                             suptr->un_ent[ix].un_adjval,
 1310                             semakptr->u.sem_base[semnum].semval));
 1311 
 1312                         if (adjval < 0) {
 1313                                 if (semakptr->u.sem_base[semnum].semval <
 1314                                     -adjval)
 1315                                         semakptr->u.sem_base[semnum].semval = 0;
 1316                                 else
 1317                                         semakptr->u.sem_base[semnum].semval +=
 1318                                             adjval;
 1319                         } else
 1320                                 semakptr->u.sem_base[semnum].semval += adjval;
 1321 
 1322                         wakeup(semakptr);
 1323                         DPRINTF(("semexit:  back from wakeup\n"));
 1324                         mtx_unlock(sema_mtxp);
 1325                         SEMUNDO_UNLOCK();
 1326                 }
 1327         }
 1328 
 1329         /*
 1330          * Deallocate the undo vector.
 1331          */
 1332         DPRINTF(("removing vector\n"));
 1333         SEMUNDO_LOCK();
 1334         suptr->un_proc = NULL;
 1335         SEMUNDO_UNLOCK();
 1336 }
 1337 
 1338 static int
 1339 sysctl_sema(SYSCTL_HANDLER_ARGS)
 1340 {
 1341 
 1342         return (SYSCTL_OUT(req, sema,
 1343             sizeof(struct semid_kernel) * seminfo.semmni));
 1344 }

Cache object: b477c496b947afbccec3f4575174bac1


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


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