Aren/NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
060a72601c
NetBSD/sys/kern/sysv_sem.c
jdolecek 2e59e9ae06 allocate virtual memory for SYSV shm, msg and semaphore structures 
separately from the bufpages, so that it would be possible to eventually
make their limits changeable in runtime

make static all local variables which do not need to be exported to other
kernel parts
2003-10-26 10:32:24 +00:00

900 lines
22 KiB
C
Raw Blame History

/* $NetBSD: sysv_sem.c,v 1.48 2003/10/26 10:32:24 jdolecek 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 1.48 2003/10/26 10:32:24 jdolecek 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 __P((struct proc *));
int semundo_adjust __P((struct proc *, struct sem_undo **, int, int, int));
void semundo_clear __P((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) {
*supptr = suptr;
break;
}
}
if (suptr == NULL) {
if (adjval == 0)
return(0);
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;
if (adjval == 0)
sunptr->un_adjval = 0;
else
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 (adjval == 0)
return(0);
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;
for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
struct undo *sunptr;
int i;
sunptr = &suptr->un_ent[0];
for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
if (sunptr->un_id == semid) {
if (semnum == -1 || sunptr->un_num == semnum) {
suptr->un_cnt--;
if (i < suptr->un_cnt) {
suptr->un_ent[i] =
suptr->un_ent[suptr->un_cnt];
i--, sunptr--;
}
}
if (semnum != -1)
break;
}
}
}
}
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.semmsl)
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);
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, j, 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.semmsl)
return(EINVAL);
semaptr = &sema[semid];
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != IPCID_TO_SEQ(SCARG(uap, semid)))
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);
}
/*
* 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];
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));
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++;
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));
suptr = NULL; /* sem_undo may have been reallocated */
if (eval != 0)
return(EINTR);
SEM_PRINTF(("semop: good morning!\n"));
/*
* Make sure that the semaphore still exists
*/
if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ||
semaptr->sem_perm._seq != IPCID_TO_SEQ(SCARG(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;
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;
}
Reference in New Issue View Git Blame Copy Permalink