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NetBSD/sys/kern/sysv_sem.c

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/* $NetBSD: sysv_sem.c,v 1.54 2004/08/05 22:06:48 enami Exp $ */
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Implementation of SVID semaphores
*
* Author: Daniel Boulet
*
* This software is provided ``AS IS'' without any warranties of any kind.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.54 2004/08/05 22:06:48 enami Exp $");
#define SYSVSEM
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/sem.h>
#include <sys/sysctl.h>
#include <sys/mount.h> /* XXX for <sys/syscallargs.h> */
#include <sys/sa.h>
#include <sys/syscallargs.h>
static int semtot = 0;
struct semid_ds *sema; /* semaphore id pool */
static struct __sem *sem; /* semaphore pool */
static struct sem_undo *semu_list; /* list of active undo structures */
static int *semu; /* undo structure pool */
#ifdef SEM_DEBUG
#define SEM_PRINTF(a) printf a
#else
#define SEM_PRINTF(a)
#endif
struct sem_undo *semu_alloc(struct proc *);
int semundo_adjust(struct proc *, struct sem_undo **, int, int, int);
void semundo_clear(int, int);
/*
* XXXSMP Once we go MP, there needs to be a lock for the semaphore system.
* Until then, we're saved by being a non-preemptive kernel.
*/
void
seminit()
{
int i, sz;
vaddr_t v;
/* Allocate pageable memory for our structures */
sz = seminfo.semmni * sizeof(struct semid_ds) +
seminfo.semmns * sizeof(struct __sem) +
seminfo.semmnu * seminfo.semusz;
if ((v = uvm_km_zalloc(kernel_map, round_page(sz))) == 0)
panic("sysv_sem: cannot allocate memory");
sema = (void *)v;
sem = (void *)(sema + seminfo.semmni);
semu = (void *)(sem + seminfo.semmns);
for (i = 0; i < seminfo.semmni; i++) {
sema[i]._sem_base = 0;
sema[i].sem_perm.mode = 0;
}
for (i = 0; i < seminfo.semmnu; i++) {
struct sem_undo *suptr = SEMU(i);
suptr->un_proc = NULL;
}
semu_list = NULL;
exithook_establish(semexit, NULL);
}
/*
* Placebo.
*/
int
sys_semconfig(l, v, retval)
struct lwp *l;
void *v;
register_t *retval;
{
*retval = 0;
return 0;
}
/*
* Allocate a new sem_undo structure for a process
* (returns ptr to structure or NULL if no more room)
*/
struct sem_undo *
semu_alloc(p)
struct proc *p;
{
int i;
struct sem_undo *suptr;
struct sem_undo **supptr;
int attempt;
/*
* Try twice to allocate something.
* (we'll purge any empty structures after the first pass so
* two passes are always enough)
*/
for (attempt = 0; attempt < 2; attempt++) {
/*
* Look for a free structure.
* Fill it in and return it if we find one.
*/
for (i = 0; i < seminfo.semmnu; i++) {
suptr = SEMU(i);
if (suptr->un_proc == NULL) {
suptr->un_next = semu_list;
semu_list = suptr;
suptr->un_cnt = 0;
suptr->un_proc = p;
return (suptr);
}
}
/*
* We didn't find a free one, if this is the first attempt
* then try to free some structures.
*/
if (attempt == 0) {
/* All the structures are in use - try to free some */
int did_something = 0;
supptr = &semu_list;
while ((suptr = *supptr) != NULL) {
if (suptr->un_cnt == 0) {
suptr->un_proc = NULL;
*supptr = suptr->un_next;
did_something = 1;
} else
supptr = &suptr->un_next;
}
/* If we didn't free anything then just give-up */
if (!did_something)
return (NULL);
} else {
/*
* The second pass failed even though we freed
* something after the first pass!
* This is IMPOSSIBLE!
*/
panic("semu_alloc - second attempt failed");
}
}
return NULL;
}
/*
* Adjust a particular entry for a particular proc
*/
int
semundo_adjust(p, supptr, semid, semnum, adjval)
struct proc *p;
struct sem_undo **supptr;
int semid, semnum;
int adjval;
{
struct sem_undo *suptr;
struct undo *sunptr;
int i;
/*
* Look for and remember the sem_undo if the caller doesn't
* provide it
*/
suptr = *supptr;
if (suptr == NULL) {
for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next)
if (suptr->un_proc == p)
break;
if (suptr == NULL) {
suptr = semu_alloc(p);
if (suptr == NULL)
return (ENOSPC);
}
*supptr = suptr;
}
/*
* Look for the requested entry and adjust it (delete if
* adjval becomes 0).
*/
sunptr = &suptr->un_ent[0];
for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
if (sunptr->un_id != semid || sunptr->un_num != semnum)
continue;
sunptr->un_adjval += adjval;
if (sunptr->un_adjval == 0) {
suptr->un_cnt--;
if (i < suptr->un_cnt)
suptr->un_ent[i] =
suptr->un_ent[suptr->un_cnt];
}
return (0);
}
/* Didn't find the right entry - create it */
if (suptr->un_cnt == SEMUME)
return (EINVAL);
sunptr = &suptr->un_ent[suptr->un_cnt];
suptr->un_cnt++;
sunptr->un_adjval = adjval;
sunptr->un_id = semid;
sunptr->un_num = semnum;
return (0);
}
void
semundo_clear(semid, semnum)
int semid, semnum;
{
struct sem_undo *suptr;
struct undo *sunptr, *sunend;
for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next)
for (sunptr = &suptr->un_ent[0],
sunend = sunptr + suptr->un_cnt; sunptr < sunend;) {
if (sunptr->un_id == semid) {
if (semnum == -1 || sunptr->un_num == semnum) {
suptr->un_cnt--;
sunend--;
if (sunptr != sunend)
*sunptr = *sunend;
if (semnum != -1)
break;
else
continue;
}
}
sunptr++;
}
}
int
sys_____semctl13(l, v, retval)
struct lwp *l;
void *v;
register_t *retval;
{
struct sys_____semctl13_args /* {
syscallarg(int) semid;
syscallarg(int) semnum;
syscallarg(int) cmd;
syscallarg(union __semun *) arg;
} */ *uap = v;
struct proc *p = l->l_proc;
struct semid_ds sembuf;
int cmd, error;
void *pass_arg;
union __semun karg;
cmd = SCARG(uap, cmd);
switch (cmd) {
case IPC_SET:
case IPC_STAT:
pass_arg = &sembuf;
break;
case GETALL:
case SETVAL:
case SETALL:
pass_arg = &karg;
break;
default:
pass_arg = NULL;
break;
}
if (pass_arg) {
error = copyin(SCARG(uap, arg), &karg, sizeof(karg));
if (error)
return error;
if (cmd == IPC_SET) {
error = copyin(karg.buf, &sembuf, sizeof(sembuf));
if (error)
return (error);
}
}
error = semctl1(p, SCARG(uap, semid), SCARG(uap, semnum), cmd,
pass_arg, retval);
if (error == 0 && cmd == IPC_STAT)
error = copyout(&sembuf, karg.buf, sizeof(sembuf));
return (error);
}
int
semctl1(p, semid, semnum, cmd, v, retval)
struct proc *p;
int semid, semnum, cmd;
void *v;
register_t *retval;
{
struct ucred *cred = p->p_ucred;
union __semun *arg = v;
struct semid_ds *sembuf = v, *semaptr;
int i, error, ix;
SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n",
semid, semnum, cmd, v));
ix = IPCID_TO_IX(semid);
if (ix < 0 || ix >= seminfo.semmni)
return (EINVAL);
semaptr = &sema[ix];
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != IPCID_TO_SEQ(semid))
return (EINVAL);
switch (cmd) {
case IPC_RMID:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0)
return (error);
semaptr->sem_perm.cuid = cred->cr_uid;
semaptr->sem_perm.uid = cred->cr_uid;
semtot -= semaptr->sem_nsems;
for (i = semaptr->_sem_base - sem; i < semtot; i++)
sem[i] = sem[i + semaptr->sem_nsems];
for (i = 0; i < seminfo.semmni; i++) {
if ((sema[i].sem_perm.mode & SEM_ALLOC) &&
sema[i]._sem_base > semaptr->_sem_base)
sema[i]._sem_base -= semaptr->sem_nsems;
}
semaptr->sem_perm.mode = 0;
semundo_clear(ix, -1);
wakeup(semaptr);
break;
case IPC_SET:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
return (error);
semaptr->sem_perm.uid = sembuf->sem_perm.uid;
semaptr->sem_perm.gid = sembuf->sem_perm.gid;
semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
(sembuf->sem_perm.mode & 0777);
semaptr->sem_ctime = time.tv_sec;
break;
case IPC_STAT:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return (error);
memcpy(sembuf, semaptr, sizeof(struct semid_ds));
break;
case GETNCNT:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return (error);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return (EINVAL);
*retval = semaptr->_sem_base[semnum].semncnt;
break;
case GETPID:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return (error);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return (EINVAL);
*retval = semaptr->_sem_base[semnum].sempid;
break;
case GETVAL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return (error);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return (EINVAL);
*retval = semaptr->_sem_base[semnum].semval;
break;
case GETALL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return (error);
for (i = 0; i < semaptr->sem_nsems; i++) {
error = copyout(&semaptr->_sem_base[i].semval,
&arg->array[i], sizeof(arg->array[i]));
if (error != 0)
break;
}
break;
case GETZCNT:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return (error);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return (EINVAL);
*retval = semaptr->_sem_base[semnum].semzcnt;
break;
case SETVAL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
return (error);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return (EINVAL);
semaptr->_sem_base[semnum].semval = arg->val;
semundo_clear(ix, semnum);
wakeup(semaptr);
break;
case SETALL:
if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
return (error);
for (i = 0; i < semaptr->sem_nsems; i++) {
error = copyin(&arg->array[i],
&semaptr->_sem_base[i].semval,
sizeof(arg->array[i]));
if (error != 0)
break;
}
semundo_clear(ix, -1);
wakeup(semaptr);
break;
default:
return (EINVAL);
}
return (error);
}
int
sys_semget(l, v, retval)
struct lwp *l;
void *v;
register_t *retval;
{
struct sys_semget_args /* {
syscallarg(key_t) key;
syscallarg(int) nsems;
syscallarg(int) semflg;
} */ *uap = v;
int semid, eval;
int key = SCARG(uap, key);
int nsems = SCARG(uap, nsems);
int semflg = SCARG(uap, semflg);
struct ucred *cred = l->l_proc->p_ucred;
SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));
if (key != IPC_PRIVATE) {
for (semid = 0; semid < seminfo.semmni; semid++) {
if ((sema[semid].sem_perm.mode & SEM_ALLOC) &&
sema[semid].sem_perm._key == key)
break;
}
if (semid < seminfo.semmni) {
SEM_PRINTF(("found public key\n"));
if ((eval = ipcperm(cred, &sema[semid].sem_perm,
semflg & 0700)))
return (eval);
if (nsems > 0 && sema[semid].sem_nsems < nsems) {
SEM_PRINTF(("too small\n"));
return (EINVAL);
}
if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
SEM_PRINTF(("not exclusive\n"));
return (EEXIST);
}
goto found;
}
}
SEM_PRINTF(("need to allocate the semid_ds\n"));
if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
if (nsems <= 0 || nsems > seminfo.semmsl) {
SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems,
seminfo.semmsl));
return (EINVAL);
}
if (nsems > seminfo.semmns - semtot) {
SEM_PRINTF(("not enough semaphores left "
"(need %d, got %d)\n",
nsems, seminfo.semmns - semtot));
return (ENOSPC);
}
for (semid = 0; semid < seminfo.semmni; semid++) {
if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0)
break;
}
if (semid == seminfo.semmni) {
SEM_PRINTF(("no more semid_ds's available\n"));
return (ENOSPC);
}
SEM_PRINTF(("semid %d is available\n", semid));
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;
memset(sema[semid]._sem_base, 0,
sizeof(sema[semid]._sem_base[0]) * nsems);
SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base,
&sem[semtot]));
} else {
SEM_PRINTF(("didn't find it and wasn't asked to create it\n"));
return (ENOENT);
}
found:
*retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm);
return (0);
}
int
sys_semop(l, v, retval)
struct lwp *l;
void *v;
register_t *retval;
{
struct sys_semop_args /* {
syscallarg(int) semid;
syscallarg(struct sembuf *) sops;
syscallarg(size_t) nsops;
} */ *uap = v;
struct proc *p = l->l_proc;
int semid = SCARG(uap, semid), seq;
size_t nsops = SCARG(uap, nsops);
struct sembuf sops[MAX_SOPS];
struct semid_ds *semaptr;
struct sembuf *sopptr = NULL;
struct __sem *semptr = NULL;
struct sem_undo *suptr = NULL;
struct ucred *cred = p->p_ucred;
int i, eval;
int do_wakeup, do_undos;
SEM_PRINTF(("call to semop(%d, %p, %lld)\n", semid, sops,
(long long)nsops));
semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
if (semid < 0 || semid >= seminfo.semmni)
return (EINVAL);
semaptr = &sema[semid];
seq = IPCID_TO_SEQ(SCARG(uap, semid));
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != seq)
return (EINVAL);
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W))) {
SEM_PRINTF(("eval = %d from ipaccess\n", eval));
return (eval);
}
if (nsops > MAX_SOPS) {
SEM_PRINTF(("too many sops (max=%d, nsops=%lld)\n", MAX_SOPS,
(long long)nsops));
return (E2BIG);
}
if ((eval = copyin(SCARG(uap, sops),
sops, nsops * sizeof(sops[0]))) != 0) {
SEM_PRINTF(("eval = %d from copyin(%p, %p, %lld)\n", eval,
SCARG(uap, sops), &sops,
(long long)(nsops * sizeof(sops[0]))));
return (eval);
}
for (i = 0; i < nsops; i++)
if (sops[i].sem_num >= semaptr->sem_nsems)
return (EFBIG);
/*
* 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];
semptr = &semaptr->_sem_base[sopptr->sem_num];
SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, "
"semptr=%p, 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"));
if (sopptr->sem_op < 0) {
if ((int)(semptr->semval +
sopptr->sem_op) < 0) {
SEM_PRINTF(("semop: "
"can't do it now\n"));
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) {
SEM_PRINTF(("semop: not zero now\n"));
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
*/
SEM_PRINTF(("semop: rollback 0 through %d\n", i - 1));
while (i-- > 0)
semaptr->_sem_base[sops[i].sem_num].semval -=
sops[i].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++;
SEM_PRINTF(("semop: good night!\n"));
eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH,
"semwait", 0);
SEM_PRINTF(("semop: good morning (eval=%d)!\n", eval));
/*
* Make sure that the semaphore still exists
*/
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != seq) {
/* 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.
*/
semptr = &semaptr->_sem_base[sopptr->sem_num];
if (sopptr->sem_op == 0)
semptr->semzcnt--;
else
semptr->semncnt--;
/*
* Is it really morning, or was our sleep interrupted?
* (Delayed check of tsleep() return code because we
* need to decrement sem[nz]cnt either way.)
*/
if (eval != 0)
return (EINTR);
SEM_PRINTF(("semop: good morning!\n"));
}
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.
*/
while (i-- > 0) {
if ((sops[i].sem_flg & SEM_UNDO) == 0)
continue;
adjval = sops[i].sem_op;
if (adjval == 0)
continue;
if (semundo_adjust(p, &suptr, semid,
sops[i].sem_num, adjval) != 0)
panic("semop - can't undo undos");
}
for (i = 0; i < nsops; i++)
semaptr->_sem_base[sops[i].sem_num].semval -=
sops[i].sem_op;
SEM_PRINTF(("eval = %d from semundo_adjust\n", eval));
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) {
SEM_PRINTF(("semop: doing wakeup\n"));
#ifdef SEM_WAKEUP
sem_wakeup((caddr_t)semaptr);
#else
wakeup((caddr_t)semaptr);
#endif
SEM_PRINTF(("semop: back from wakeup\n"));
}
SEM_PRINTF(("semop: done\n"));
*retval = 0;
return (0);
}
/*
* Go through the undo structures for this process and apply the
* adjustments to semaphores.
*/
/*ARGSUSED*/
void
semexit(p, v)
struct proc *p;
void *v;
{
struct sem_undo *suptr;
struct sem_undo **supptr;
/*
* 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 there is no undo vector, skip to the end.
*/
if (suptr == NULL)
return;
/*
* We now have an undo vector for this process.
*/
SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p,
suptr->un_cnt));
/*
* 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");
SEM_PRINTF(("semexit: %p 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));
if (adjval < 0 &&
semaptr->_sem_base[semnum].semval < -adjval)
semaptr->_sem_base[semnum].semval = 0;
else
semaptr->_sem_base[semnum].semval += adjval;
#ifdef SEM_WAKEUP
sem_wakeup((caddr_t)semaptr);
#else
wakeup((caddr_t)semaptr);
#endif
SEM_PRINTF(("semexit: back from wakeup\n"));
}
}
/*
* Deallocate the undo vector.
*/
SEM_PRINTF(("removing vector\n"));
suptr->un_proc = NULL;
*supptr = suptr->un_next;
}
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