984 lines
22 KiB
C
984 lines
22 KiB
C
/* $Id: sysv_sem.c,v 1.18 1997/02/22 09:39:22 peter Exp $ */
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/*
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* Implementation of SVID semaphores
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*
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* Author: Daniel Boulet
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*
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* This software is provided ``AS IS'' without any warranties of any kind.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/sem.h>
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#include <sys/sysent.h>
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static void seminit __P((void *));
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SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL)
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#ifndef _SYS_SYSPROTO_H_
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struct __semctl_args;
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int __semctl __P((struct proc *p, struct __semctl_args *uap, int *retval));
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struct semget_args;
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int semget __P((struct proc *p, struct semget_args *uap, int *retval));
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struct semop_args;
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int semop __P((struct proc *p, struct semop_args *uap, int *retval));
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struct semconfig_args;
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int semconfig __P((struct proc *p, struct semconfig_args *uap,
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int *retval));
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#endif
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static struct sem_undo *semu_alloc __P((struct proc *p));
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static int semundo_adjust __P((struct proc *p, struct sem_undo **supptr,
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int semid, int semnum, int adjval));
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static void semundo_clear __P((int semid, int semnum));
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/* XXX casting to (sy_call_t *) is bogus, as usual. */
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static sy_call_t *semcalls[] = {
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(sy_call_t *)__semctl, (sy_call_t *)semget,
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(sy_call_t *)semop, (sy_call_t *)semconfig
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};
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static int semtot = 0;
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struct semid_ds *sema; /* semaphore id pool */
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struct sem *sem; /* semaphore pool */
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static struct sem_undo *semu_list; /* list of active undo structures */
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int *semu; /* undo structure pool */
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static struct proc *semlock_holder = NULL;
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void
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seminit(dummy)
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void *dummy;
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{
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register int i;
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if (sema == NULL)
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panic("sema is NULL");
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if (semu == NULL)
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panic("semu is NULL");
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for (i = 0; i < seminfo.semmni; i++) {
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sema[i].sem_base = 0;
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sema[i].sem_perm.mode = 0;
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}
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for (i = 0; i < seminfo.semmnu; i++) {
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register struct sem_undo *suptr = SEMU(i);
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suptr->un_proc = NULL;
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}
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semu_list = NULL;
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}
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/*
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* Entry point for all SEM calls
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*/
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int
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semsys(p, uap, retval)
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struct proc *p;
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/* XXX actually varargs. */
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struct semsys_args /* {
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u_int which;
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int a2;
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int a3;
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int a4;
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int a5;
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} */ *uap;
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int *retval;
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{
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while (semlock_holder != NULL && semlock_holder != p)
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(void) tsleep((caddr_t)&semlock_holder, (PZERO - 4), "semsys", 0);
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if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
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return (EINVAL);
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return ((*semcalls[uap->which])(p, &uap->a2, retval));
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}
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/*
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* Lock or unlock the entire semaphore facility.
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*
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* This will probably eventually evolve into a general purpose semaphore
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* facility status enquiry mechanism (I don't like the "read /dev/kmem"
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* approach currently taken by ipcs and the amount of info that we want
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* to be able to extract for ipcs is probably beyond what the capability
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* of the getkerninfo facility.
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*
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* At the time that the current version of semconfig was written, ipcs is
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* the only user of the semconfig facility. It uses it to ensure that the
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* semaphore facility data structures remain static while it fishes around
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* in /dev/kmem.
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*/
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#ifndef _SYS_SYSPROTO_H_
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struct semconfig_args {
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semconfig_ctl_t flag;
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};
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#endif
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int
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semconfig(p, uap, retval)
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struct proc *p;
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struct semconfig_args *uap;
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int *retval;
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{
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int eval = 0;
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switch (uap->flag) {
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case SEM_CONFIG_FREEZE:
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semlock_holder = p;
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break;
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case SEM_CONFIG_THAW:
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semlock_holder = NULL;
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wakeup((caddr_t)&semlock_holder);
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break;
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default:
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printf("semconfig: unknown flag parameter value (%d) - ignored\n",
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uap->flag);
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eval = EINVAL;
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break;
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}
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*retval = 0;
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return(eval);
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}
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/*
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* Allocate a new sem_undo structure for a process
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* (returns ptr to structure or NULL if no more room)
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*/
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static struct sem_undo *
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semu_alloc(p)
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struct proc *p;
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{
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register int i;
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register struct sem_undo *suptr;
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register struct sem_undo **supptr;
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int attempt;
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/*
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* Try twice to allocate something.
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* (we'll purge any empty structures after the first pass so
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* two passes are always enough)
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*/
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for (attempt = 0; attempt < 2; attempt++) {
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/*
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* Look for a free structure.
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* Fill it in and return it if we find one.
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*/
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for (i = 0; i < seminfo.semmnu; i++) {
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suptr = SEMU(i);
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if (suptr->un_proc == NULL) {
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suptr->un_next = semu_list;
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semu_list = suptr;
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suptr->un_cnt = 0;
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suptr->un_proc = p;
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return(suptr);
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}
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}
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/*
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* We didn't find a free one, if this is the first attempt
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* then try to free some structures.
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*/
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if (attempt == 0) {
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/* All the structures are in use - try to free some */
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int did_something = 0;
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supptr = &semu_list;
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while ((suptr = *supptr) != NULL) {
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if (suptr->un_cnt == 0) {
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suptr->un_proc = NULL;
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*supptr = suptr->un_next;
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did_something = 1;
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} else
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supptr = &(suptr->un_next);
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}
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/* If we didn't free anything then just give-up */
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if (!did_something)
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return(NULL);
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} else {
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/*
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* The second pass failed even though we freed
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* something after the first pass!
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* This is IMPOSSIBLE!
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*/
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panic("semu_alloc - second attempt failed");
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}
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}
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return (NULL);
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}
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/*
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* Adjust a particular entry for a particular proc
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*/
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static int
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semundo_adjust(p, supptr, semid, semnum, adjval)
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register struct proc *p;
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struct sem_undo **supptr;
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int semid, semnum;
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int adjval;
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{
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register struct sem_undo *suptr;
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register struct undo *sunptr;
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int i;
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/* Look for and remember the sem_undo if the caller doesn't provide
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it */
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suptr = *supptr;
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if (suptr == NULL) {
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for (suptr = semu_list; suptr != NULL;
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suptr = suptr->un_next) {
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if (suptr->un_proc == p) {
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*supptr = suptr;
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break;
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}
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}
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if (suptr == NULL) {
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if (adjval == 0)
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return(0);
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suptr = semu_alloc(p);
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if (suptr == NULL)
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return(ENOSPC);
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*supptr = suptr;
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}
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}
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/*
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* Look for the requested entry and adjust it (delete if adjval becomes
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* 0).
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*/
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sunptr = &suptr->un_ent[0];
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for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
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if (sunptr->un_id != semid || sunptr->un_num != semnum)
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continue;
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if (adjval == 0)
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sunptr->un_adjval = 0;
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else
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sunptr->un_adjval += adjval;
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if (sunptr->un_adjval == 0) {
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suptr->un_cnt--;
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if (i < suptr->un_cnt)
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suptr->un_ent[i] =
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suptr->un_ent[suptr->un_cnt];
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}
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return(0);
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}
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/* Didn't find the right entry - create it */
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if (adjval == 0)
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return(0);
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if (suptr->un_cnt != SEMUME) {
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sunptr = &suptr->un_ent[suptr->un_cnt];
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suptr->un_cnt++;
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sunptr->un_adjval = adjval;
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sunptr->un_id = semid; sunptr->un_num = semnum;
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} else
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return(EINVAL);
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return(0);
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}
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static void
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semundo_clear(semid, semnum)
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int semid, semnum;
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{
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register struct sem_undo *suptr;
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for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
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register struct undo *sunptr = &suptr->un_ent[0];
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register int i = 0;
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while (i < suptr->un_cnt) {
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if (sunptr->un_id == semid) {
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if (semnum == -1 || sunptr->un_num == semnum) {
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suptr->un_cnt--;
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if (i < suptr->un_cnt) {
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suptr->un_ent[i] =
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suptr->un_ent[suptr->un_cnt];
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continue;
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}
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}
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if (semnum != -1)
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break;
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}
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i++, sunptr++;
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}
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}
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}
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/*
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* Note that the user-mode half of this passes a union, not a pointer
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*/
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#ifndef _SYS_SYSPROTO_H_
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struct __semctl_args {
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int semid;
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int semnum;
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int cmd;
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union semun *arg;
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};
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#endif
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int
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__semctl(p, uap, retval)
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struct proc *p;
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register struct __semctl_args *uap;
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int *retval;
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{
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int semid = uap->semid;
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int semnum = uap->semnum;
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int cmd = uap->cmd;
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union semun *arg = uap->arg;
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union semun real_arg;
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struct ucred *cred = p->p_ucred;
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int i, rval, eval;
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struct semid_ds sbuf;
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register struct semid_ds *semaptr;
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#ifdef SEM_DEBUG
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printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
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#endif
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semid = IPCID_TO_IX(semid);
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if (semid < 0 || semid >= seminfo.semmsl)
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return(EINVAL);
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semaptr = &sema[semid];
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if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
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semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
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return(EINVAL);
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eval = 0;
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rval = 0;
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switch (cmd) {
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case IPC_RMID:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
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return(eval);
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semaptr->sem_perm.cuid = cred->cr_uid;
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semaptr->sem_perm.uid = cred->cr_uid;
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semtot -= semaptr->sem_nsems;
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for (i = semaptr->sem_base - sem; i < semtot; i++)
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sem[i] = sem[i + semaptr->sem_nsems];
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for (i = 0; i < seminfo.semmni; i++) {
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if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
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sema[i].sem_base > semaptr->sem_base)
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sema[i].sem_base -= semaptr->sem_nsems;
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}
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semaptr->sem_perm.mode = 0;
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semundo_clear(semid, -1);
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wakeup((caddr_t)semaptr);
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break;
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case IPC_SET:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
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return(eval);
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if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
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return(eval);
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if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf,
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sizeof(sbuf))) != 0)
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return(eval);
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semaptr->sem_perm.uid = sbuf.sem_perm.uid;
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semaptr->sem_perm.gid = sbuf.sem_perm.gid;
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semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
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(sbuf.sem_perm.mode & 0777);
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semaptr->sem_ctime = time.tv_sec;
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break;
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case IPC_STAT:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
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return(eval);
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if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
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return(eval);
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eval = copyout((caddr_t)semaptr, real_arg.buf,
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sizeof(struct semid_ds));
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break;
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case GETNCNT:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
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return(eval);
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if (semnum < 0 || semnum >= semaptr->sem_nsems)
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return(EINVAL);
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rval = semaptr->sem_base[semnum].semncnt;
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break;
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case GETPID:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
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return(eval);
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if (semnum < 0 || semnum >= semaptr->sem_nsems)
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return(EINVAL);
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rval = semaptr->sem_base[semnum].sempid;
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break;
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case GETVAL:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
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return(eval);
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if (semnum < 0 || semnum >= semaptr->sem_nsems)
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return(EINVAL);
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rval = semaptr->sem_base[semnum].semval;
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break;
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case GETALL:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
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return(eval);
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if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
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return(eval);
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for (i = 0; i < semaptr->sem_nsems; i++) {
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eval = copyout((caddr_t)&semaptr->sem_base[i].semval,
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&real_arg.array[i], sizeof(real_arg.array[0]));
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if (eval != 0)
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break;
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}
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break;
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case GETZCNT:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
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return(eval);
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if (semnum < 0 || semnum >= semaptr->sem_nsems)
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return(EINVAL);
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rval = semaptr->sem_base[semnum].semzcnt;
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break;
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case SETVAL:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
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return(eval);
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if (semnum < 0 || semnum >= semaptr->sem_nsems)
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return(EINVAL);
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if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
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return(eval);
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semaptr->sem_base[semnum].semval = real_arg.val;
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semundo_clear(semid, semnum);
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wakeup((caddr_t)semaptr);
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break;
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case SETALL:
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if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
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return(eval);
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if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
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return(eval);
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for (i = 0; i < semaptr->sem_nsems; i++) {
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eval = copyin(&real_arg.array[i],
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(caddr_t)&semaptr->sem_base[i].semval,
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sizeof(real_arg.array[0]));
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if (eval != 0)
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break;
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}
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semundo_clear(semid, -1);
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wakeup((caddr_t)semaptr);
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break;
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default:
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return(EINVAL);
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}
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if (eval == 0)
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*retval = rval;
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return(eval);
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}
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#ifndef _SYS_SYSPROTO_H_
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struct semget_args {
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key_t key;
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int nsems;
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int semflg;
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};
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#endif
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int
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semget(p, uap, retval)
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struct proc *p;
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register struct semget_args *uap;
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int *retval;
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{
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int semid, eval;
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int key = uap->key;
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int nsems = uap->nsems;
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int semflg = uap->semflg;
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struct ucred *cred = p->p_ucred;
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#ifdef SEM_DEBUG
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printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
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#endif
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if (key != IPC_PRIVATE) {
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for (semid = 0; semid < seminfo.semmni; semid++) {
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if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
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sema[semid].sem_perm.key == key)
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break;
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}
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if (semid < seminfo.semmni) {
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#ifdef SEM_DEBUG
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printf("found public key\n");
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#endif
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if ((eval = ipcperm(cred, &sema[semid].sem_perm,
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semflg & 0700)))
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return(eval);
|
|
if (nsems > 0 && sema[semid].sem_nsems < nsems) {
|
|
#ifdef SEM_DEBUG
|
|
printf("too small\n");
|
|
#endif
|
|
return(EINVAL);
|
|
}
|
|
if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
|
|
#ifdef SEM_DEBUG
|
|
printf("not exclusive\n");
|
|
#endif
|
|
return(EEXIST);
|
|
}
|
|
goto found;
|
|
}
|
|
}
|
|
|
|
#ifdef SEM_DEBUG
|
|
printf("need to allocate the semid_ds\n");
|
|
#endif
|
|
if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
|
|
if (nsems <= 0 || nsems > seminfo.semmsl) {
|
|
#ifdef SEM_DEBUG
|
|
printf("nsems out of range (0<%d<=%d)\n", nsems,
|
|
seminfo.semmsl);
|
|
#endif
|
|
return(EINVAL);
|
|
}
|
|
if (nsems > seminfo.semmns - semtot) {
|
|
#ifdef SEM_DEBUG
|
|
printf("not enough semaphores left (need %d, got %d)\n",
|
|
nsems, seminfo.semmns - semtot);
|
|
#endif
|
|
return(ENOSPC);
|
|
}
|
|
for (semid = 0; semid < seminfo.semmni; semid++) {
|
|
if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
|
|
break;
|
|
}
|
|
if (semid == seminfo.semmni) {
|
|
#ifdef SEM_DEBUG
|
|
printf("no more semid_ds's available\n");
|
|
#endif
|
|
return(ENOSPC);
|
|
}
|
|
#ifdef SEM_DEBUG
|
|
printf("semid %d is available\n", semid);
|
|
#endif
|
|
sema[semid].sem_perm.key = key;
|
|
sema[semid].sem_perm.cuid = cred->cr_uid;
|
|
sema[semid].sem_perm.uid = cred->cr_uid;
|
|
sema[semid].sem_perm.cgid = cred->cr_gid;
|
|
sema[semid].sem_perm.gid = cred->cr_gid;
|
|
sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
|
|
sema[semid].sem_perm.seq =
|
|
(sema[semid].sem_perm.seq + 1) & 0x7fff;
|
|
sema[semid].sem_nsems = nsems;
|
|
sema[semid].sem_otime = 0;
|
|
sema[semid].sem_ctime = time.tv_sec;
|
|
sema[semid].sem_base = &sem[semtot];
|
|
semtot += nsems;
|
|
bzero(sema[semid].sem_base,
|
|
sizeof(sema[semid].sem_base[0])*nsems);
|
|
#ifdef SEM_DEBUG
|
|
printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base,
|
|
&sem[semtot]);
|
|
#endif
|
|
} else {
|
|
#ifdef SEM_DEBUG
|
|
printf("didn't find it and wasn't asked to create it\n");
|
|
#endif
|
|
return(ENOENT);
|
|
}
|
|
|
|
found:
|
|
*retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
|
|
return(0);
|
|
}
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct semop_args {
|
|
int semid;
|
|
struct sembuf *sops;
|
|
int nsops;
|
|
};
|
|
#endif
|
|
|
|
int
|
|
semop(p, uap, retval)
|
|
struct proc *p;
|
|
register struct semop_args *uap;
|
|
int *retval;
|
|
{
|
|
int semid = uap->semid;
|
|
int nsops = uap->nsops;
|
|
struct sembuf sops[MAX_SOPS];
|
|
register struct semid_ds *semaptr;
|
|
register struct sembuf *sopptr;
|
|
register struct sem *semptr;
|
|
struct sem_undo *suptr = NULL;
|
|
struct ucred *cred = p->p_ucred;
|
|
int i, j, eval;
|
|
int do_wakeup, do_undos;
|
|
|
|
#ifdef SEM_DEBUG
|
|
printf("call to semop(%d, 0x%x, %d)\n", semid, sops, nsops);
|
|
#endif
|
|
|
|
semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
|
|
|
|
if (semid < 0 || semid >= seminfo.semmsl)
|
|
return(EINVAL);
|
|
|
|
semaptr = &sema[semid];
|
|
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
|
|
return(EINVAL);
|
|
if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid))
|
|
return(EINVAL);
|
|
|
|
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W))) {
|
|
#ifdef SEM_DEBUG
|
|
printf("eval = %d from ipaccess\n", eval);
|
|
#endif
|
|
return(eval);
|
|
}
|
|
|
|
if (nsops > MAX_SOPS) {
|
|
#ifdef SEM_DEBUG
|
|
printf("too many sops (max=%d, nsops=%d)\n", MAX_SOPS, nsops);
|
|
#endif
|
|
return(E2BIG);
|
|
}
|
|
|
|
if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) {
|
|
#ifdef SEM_DEBUG
|
|
printf("eval = %d from copyin(%08x, %08x, %d)\n", eval,
|
|
uap->sops, &sops, nsops * sizeof(sops[0]));
|
|
#endif
|
|
return(eval);
|
|
}
|
|
|
|
/*
|
|
* Loop trying to satisfy the vector of requests.
|
|
* If we reach a point where we must wait, any requests already
|
|
* performed are rolled back and we go to sleep until some other
|
|
* process wakes us up. At this point, we start all over again.
|
|
*
|
|
* This ensures that from the perspective of other tasks, a set
|
|
* of requests is atomic (never partially satisfied).
|
|
*/
|
|
do_undos = 0;
|
|
|
|
for (;;) {
|
|
do_wakeup = 0;
|
|
|
|
for (i = 0; i < nsops; i++) {
|
|
sopptr = &sops[i];
|
|
|
|
if (sopptr->sem_num >= semaptr->sem_nsems)
|
|
return(EFBIG);
|
|
|
|
semptr = &semaptr->sem_base[sopptr->sem_num];
|
|
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
|
|
semaptr, semaptr->sem_base, semptr,
|
|
sopptr->sem_num, semptr->semval, sopptr->sem_op,
|
|
(sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait");
|
|
#endif
|
|
|
|
if (sopptr->sem_op < 0) {
|
|
if (semptr->semval + sopptr->sem_op < 0) {
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: can't do it now\n");
|
|
#endif
|
|
break;
|
|
} else {
|
|
semptr->semval += sopptr->sem_op;
|
|
if (semptr->semval == 0 &&
|
|
semptr->semzcnt > 0)
|
|
do_wakeup = 1;
|
|
}
|
|
if (sopptr->sem_flg & SEM_UNDO)
|
|
do_undos = 1;
|
|
} else if (sopptr->sem_op == 0) {
|
|
if (semptr->semval > 0) {
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: not zero now\n");
|
|
#endif
|
|
break;
|
|
}
|
|
} else {
|
|
if (semptr->semncnt > 0)
|
|
do_wakeup = 1;
|
|
semptr->semval += sopptr->sem_op;
|
|
if (sopptr->sem_flg & SEM_UNDO)
|
|
do_undos = 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Did we get through the entire vector?
|
|
*/
|
|
if (i >= nsops)
|
|
goto done;
|
|
|
|
/*
|
|
* No ... rollback anything that we've already done
|
|
*/
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: rollback 0 through %d\n", i-1);
|
|
#endif
|
|
for (j = 0; j < i; j++)
|
|
semaptr->sem_base[sops[j].sem_num].semval -=
|
|
sops[j].sem_op;
|
|
|
|
/*
|
|
* If the request that we couldn't satisfy has the
|
|
* NOWAIT flag set then return with EAGAIN.
|
|
*/
|
|
if (sopptr->sem_flg & IPC_NOWAIT)
|
|
return(EAGAIN);
|
|
|
|
if (sopptr->sem_op == 0)
|
|
semptr->semzcnt++;
|
|
else
|
|
semptr->semncnt++;
|
|
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: good night!\n");
|
|
#endif
|
|
eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH,
|
|
"semwait", 0);
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: good morning (eval=%d)!\n", eval);
|
|
#endif
|
|
|
|
suptr = NULL; /* sem_undo may have been reallocated */
|
|
|
|
if (eval != 0)
|
|
return(EINTR);
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: good morning!\n");
|
|
#endif
|
|
|
|
/*
|
|
* Make sure that the semaphore still exists
|
|
*/
|
|
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
|
|
semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
|
|
/* The man page says to return EIDRM. */
|
|
/* Unfortunately, BSD doesn't define that code! */
|
|
#ifdef EIDRM
|
|
return(EIDRM);
|
|
#else
|
|
return(EINVAL);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* The semaphore is still alive. Readjust the count of
|
|
* waiting processes.
|
|
*/
|
|
if (sopptr->sem_op == 0)
|
|
semptr->semzcnt--;
|
|
else
|
|
semptr->semncnt--;
|
|
}
|
|
|
|
done:
|
|
/*
|
|
* Process any SEM_UNDO requests.
|
|
*/
|
|
if (do_undos) {
|
|
for (i = 0; i < nsops; i++) {
|
|
/*
|
|
* We only need to deal with SEM_UNDO's for non-zero
|
|
* op's.
|
|
*/
|
|
int adjval;
|
|
|
|
if ((sops[i].sem_flg & SEM_UNDO) == 0)
|
|
continue;
|
|
adjval = sops[i].sem_op;
|
|
if (adjval == 0)
|
|
continue;
|
|
eval = semundo_adjust(p, &suptr, semid,
|
|
sops[i].sem_num, -adjval);
|
|
if (eval == 0)
|
|
continue;
|
|
|
|
/*
|
|
* Oh-Oh! We ran out of either sem_undo's or undo's.
|
|
* Rollback the adjustments to this point and then
|
|
* rollback the semaphore ups and down so we can return
|
|
* with an error with all structures restored. We
|
|
* rollback the undo's in the exact reverse order that
|
|
* we applied them. This guarantees that we won't run
|
|
* out of space as we roll things back out.
|
|
*/
|
|
for (j = i - 1; j >= 0; j--) {
|
|
if ((sops[j].sem_flg & SEM_UNDO) == 0)
|
|
continue;
|
|
adjval = sops[j].sem_op;
|
|
if (adjval == 0)
|
|
continue;
|
|
if (semundo_adjust(p, &suptr, semid,
|
|
sops[j].sem_num, adjval) != 0)
|
|
panic("semop - can't undo undos");
|
|
}
|
|
|
|
for (j = 0; j < nsops; j++)
|
|
semaptr->sem_base[sops[j].sem_num].semval -=
|
|
sops[j].sem_op;
|
|
|
|
#ifdef SEM_DEBUG
|
|
printf("eval = %d from semundo_adjust\n", eval);
|
|
#endif
|
|
return(eval);
|
|
} /* loop through the sops */
|
|
} /* if (do_undos) */
|
|
|
|
/* We're definitely done - set the sempid's */
|
|
for (i = 0; i < nsops; i++) {
|
|
sopptr = &sops[i];
|
|
semptr = &semaptr->sem_base[sopptr->sem_num];
|
|
semptr->sempid = p->p_pid;
|
|
}
|
|
|
|
/* Do a wakeup if any semaphore was up'd. */
|
|
if (do_wakeup) {
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: doing wakeup\n");
|
|
#ifdef SEM_WAKEUP
|
|
sem_wakeup((caddr_t)semaptr);
|
|
#else
|
|
wakeup((caddr_t)semaptr);
|
|
#endif
|
|
printf("semop: back from wakeup\n");
|
|
#else
|
|
wakeup((caddr_t)semaptr);
|
|
#endif
|
|
}
|
|
#ifdef SEM_DEBUG
|
|
printf("semop: done\n");
|
|
#endif
|
|
*retval = 0;
|
|
return(0);
|
|
}
|
|
|
|
/*
|
|
* Go through the undo structures for this process and apply the adjustments to
|
|
* semaphores.
|
|
*/
|
|
void
|
|
semexit(p)
|
|
struct proc *p;
|
|
{
|
|
register struct sem_undo *suptr;
|
|
register struct sem_undo **supptr;
|
|
int did_something;
|
|
|
|
/*
|
|
* If somebody else is holding the global semaphore facility lock
|
|
* then sleep until it is released.
|
|
*/
|
|
while (semlock_holder != NULL && semlock_holder != p) {
|
|
#ifdef SEM_DEBUG
|
|
printf("semaphore facility locked - sleeping ...\n");
|
|
#endif
|
|
(void) tsleep((caddr_t)&semlock_holder, (PZERO - 4), "semext", 0);
|
|
}
|
|
|
|
did_something = 0;
|
|
|
|
/*
|
|
* Go through the chain of undo vectors looking for one
|
|
* associated with this process.
|
|
*/
|
|
|
|
for (supptr = &semu_list; (suptr = *supptr) != NULL;
|
|
supptr = &suptr->un_next) {
|
|
if (suptr->un_proc == p)
|
|
break;
|
|
}
|
|
|
|
if (suptr == NULL)
|
|
goto unlock;
|
|
|
|
#ifdef SEM_DEBUG
|
|
printf("proc @%08x has undo structure with %d entries\n", p,
|
|
suptr->un_cnt);
|
|
#endif
|
|
|
|
/*
|
|
* If there are any active undo elements then process them.
|
|
*/
|
|
if (suptr->un_cnt > 0) {
|
|
int ix;
|
|
|
|
for (ix = 0; ix < suptr->un_cnt; ix++) {
|
|
int semid = suptr->un_ent[ix].un_id;
|
|
int semnum = suptr->un_ent[ix].un_num;
|
|
int adjval = suptr->un_ent[ix].un_adjval;
|
|
struct semid_ds *semaptr;
|
|
|
|
semaptr = &sema[semid];
|
|
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0)
|
|
panic("semexit - semid not allocated");
|
|
if (semnum >= semaptr->sem_nsems)
|
|
panic("semexit - semnum out of range");
|
|
|
|
#ifdef SEM_DEBUG
|
|
printf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n",
|
|
suptr->un_proc, suptr->un_ent[ix].un_id,
|
|
suptr->un_ent[ix].un_num,
|
|
suptr->un_ent[ix].un_adjval,
|
|
semaptr->sem_base[semnum].semval);
|
|
#endif
|
|
|
|
if (adjval < 0) {
|
|
if (semaptr->sem_base[semnum].semval < -adjval)
|
|
semaptr->sem_base[semnum].semval = 0;
|
|
else
|
|
semaptr->sem_base[semnum].semval +=
|
|
adjval;
|
|
} else
|
|
semaptr->sem_base[semnum].semval += adjval;
|
|
|
|
#ifdef SEM_WAKEUP
|
|
sem_wakeup((caddr_t)semaptr);
|
|
#else
|
|
wakeup((caddr_t)semaptr);
|
|
#endif
|
|
#ifdef SEM_DEBUG
|
|
printf("semexit: back from wakeup\n");
|
|
#endif
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Deallocate the undo vector.
|
|
*/
|
|
#ifdef SEM_DEBUG
|
|
printf("removing vector\n");
|
|
#endif
|
|
suptr->un_proc = NULL;
|
|
*supptr = suptr->un_next;
|
|
|
|
unlock:
|
|
/*
|
|
* If the exiting process is holding the global semaphore facility
|
|
* lock then release it.
|
|
*/
|
|
if (semlock_holder == p) {
|
|
semlock_holder = NULL;
|
|
wakeup((caddr_t)&semlock_holder);
|
|
}
|
|
}
|