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freebsd-nq/sys/kern/sysv_sem.c
Poul-Henning Kamp 227ee8a188 Eradicate the variable "time" from the kernel, using various measures. 
"time" wasn't a atomic variable, so splfoo() protection were needed
around any access to it, unless you just wanted the seconds part.

Most uses of time.tv_sec now uses the new variable time_second instead.

gettime() changed to getmicrotime(0.

Remove a couple of unneeded splfoo() protections, the new getmicrotime()
is atomic, (until Bruce sets a breakpoint in it).

A couple of places needed random data, so use read_random() instead
of mucking about with time which isn't random.

Add a new nfs_curusec() function.

Mark a couple of bogosities involving the now disappeard time variable.

Update ffs_update() to avoid the weird "== &time" checks, by fixing the
one remaining call that passwd &time as args.

Change profiling in ncr.c to use ticks instead of time.  Resolution is
the same.

Add new function "tvtohz()" to avoid the bogus "splfoo(), add time, call
hzto() which subtracts time" sequences.

Reviewed by:	bde
1998-03-30 09:56:58 +00:00

978 lines
22 KiB
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/* $Id: sysv_sem.c,v 1.20 1997/11/06 19:29:24 phk Exp $ */
/*
* Implementation of SVID semaphores
*
* Author: Daniel Boulet
*
* This software is provided ``AS IS'' without any warranties of any kind.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/sem.h>
#include <sys/sysent.h>
static void seminit __P((void *));
SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL)
#ifndef _SYS_SYSPROTO_H_
struct __semctl_args;
int __semctl __P((struct proc *p, struct __semctl_args *uap));
struct semget_args;
int semget __P((struct proc *p, struct semget_args *uap));
struct semop_args;
int semop __P((struct proc *p, struct semop_args *uap));
struct semconfig_args;
int semconfig __P((struct proc *p, struct semconfig_args *uap));
#endif
static struct sem_undo *semu_alloc __P((struct proc *p));
static int semundo_adjust __P((struct proc *p, struct sem_undo **supptr,
int semid, int semnum, int adjval));
static void semundo_clear __P((int semid, int semnum));
/* XXX casting to (sy_call_t *) is bogus, as usual. */
static sy_call_t *semcalls[] = {
(sy_call_t *)__semctl, (sy_call_t *)semget,
(sy_call_t *)semop, (sy_call_t *)semconfig
};
static int semtot = 0;
struct semid_ds *sema; /* semaphore id pool */
struct sem *sem; /* semaphore pool */
static struct sem_undo *semu_list; /* list of active undo structures */
int *semu; /* undo structure pool */
static struct proc *semlock_holder = NULL;
void
seminit(dummy)
void *dummy;
{
register int i;
if (sema == NULL)
panic("sema is NULL");
if (semu == NULL)
panic("semu is NULL");
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++) {
register struct sem_undo *suptr = SEMU(i);
suptr->un_proc = NULL;
}
semu_list = NULL;
}
/*
* Entry point for all SEM calls
*/
int
semsys(p, uap)
struct proc *p;
/* XXX actually varargs. */
struct semsys_args /* {
u_int which;
int a2;
int a3;
int a4;
int a5;
} */ *uap;
{
while (semlock_holder != NULL && semlock_holder != p)
(void) tsleep((caddr_t)&semlock_holder, (PZERO - 4), "semsys", 0);
if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
return (EINVAL);
return ((*semcalls[uap->which])(p, &uap->a2));
}
/*
* Lock or unlock the entire semaphore facility.
*
* This will probably eventually evolve into a general purpose semaphore
* facility status enquiry mechanism (I don't like the "read /dev/kmem"
* approach currently taken by ipcs and the amount of info that we want
* to be able to extract for ipcs is probably beyond what the capability
* of the getkerninfo facility.
*
* At the time that the current version of semconfig was written, ipcs is
* the only user of the semconfig facility. It uses it to ensure that the
* semaphore facility data structures remain static while it fishes around
* in /dev/kmem.
*/
#ifndef _SYS_SYSPROTO_H_
struct semconfig_args {
semconfig_ctl_t flag;
};
#endif
int
semconfig(p, uap)
struct proc *p;
struct semconfig_args *uap;
{
int eval = 0;
switch (uap->flag) {
case SEM_CONFIG_FREEZE:
semlock_holder = p;
break;
case SEM_CONFIG_THAW:
semlock_holder = NULL;
wakeup((caddr_t)&semlock_holder);
break;
default:
printf("semconfig: unknown flag parameter value (%d) - ignored\n",
uap->flag);
eval = EINVAL;
break;
}
p->p_retval[0] = 0;
return(eval);
}
/*
* Allocate a new sem_undo structure for a process
* (returns ptr to structure or NULL if no more room)
*/
static struct sem_undo *
semu_alloc(p)
struct proc *p;
{
register int i;
register struct sem_undo *suptr;
register 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
*/
static int
semundo_adjust(p, supptr, semid, semnum, adjval)
register struct proc *p;
struct sem_undo **supptr;
int semid, semnum;
int adjval;
{
register struct sem_undo *suptr;
register 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) {
sunptr = &suptr->un_ent[suptr->un_cnt];
suptr->un_cnt++;
sunptr->un_adjval = adjval;
sunptr->un_id = semid; sunptr->un_num = semnum;
} else
return(EINVAL);
return(0);
}
static void
semundo_clear(semid, semnum)
int semid, semnum;
{
register struct sem_undo *suptr;
for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) {
register struct undo *sunptr = &suptr->un_ent[0];
register int i = 0;
while (i < suptr->un_cnt) {
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];
continue;
}
}
if (semnum != -1)
break;
}
i++, sunptr++;
}
}
}
/*
* Note that the user-mode half of this passes a union, not a pointer
*/
#ifndef _SYS_SYSPROTO_H_
struct __semctl_args {
int semid;
int semnum;
int cmd;
union semun *arg;
};
#endif
int
__semctl(p, uap)
struct proc *p;
register struct __semctl_args *uap;
{
int semid = uap->semid;
int semnum = uap->semnum;
int cmd = uap->cmd;
union semun *arg = uap->arg;
union semun real_arg;
struct ucred *cred = p->p_ucred;
int i, rval, eval;
struct semid_ds sbuf;
register struct semid_ds *semaptr;
#ifdef SEM_DEBUG
printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg);
#endif
semid = IPCID_TO_IX(semid);
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(uap->semid))
return(EINVAL);
eval = 0;
rval = 0;
switch (cmd) {
case IPC_RMID:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
return(eval);
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(semid, -1);
wakeup((caddr_t)semaptr);
break;
case IPC_SET:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_M)))
return(eval);
if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
return(eval);
if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf,
sizeof(sbuf))) != 0)
return(eval);
semaptr->sem_perm.uid = sbuf.sem_perm.uid;
semaptr->sem_perm.gid = sbuf.sem_perm.gid;
semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) |
(sbuf.sem_perm.mode & 0777);
semaptr->sem_ctime = time_second;
break;
case IPC_STAT:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return(eval);
if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
return(eval);
eval = copyout((caddr_t)semaptr, real_arg.buf,
sizeof(struct semid_ds));
break;
case GETNCNT:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return(eval);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return(EINVAL);
rval = semaptr->sem_base[semnum].semncnt;
break;
case GETPID:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return(eval);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return(EINVAL);
rval = semaptr->sem_base[semnum].sempid;
break;
case GETVAL:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return(eval);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return(EINVAL);
rval = semaptr->sem_base[semnum].semval;
break;
case GETALL:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return(eval);
if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
return(eval);
for (i = 0; i < semaptr->sem_nsems; i++) {
eval = copyout((caddr_t)&semaptr->sem_base[i].semval,
&real_arg.array[i], sizeof(real_arg.array[0]));
if (eval != 0)
break;
}
break;
case GETZCNT:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_R)))
return(eval);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return(EINVAL);
rval = semaptr->sem_base[semnum].semzcnt;
break;
case SETVAL:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
return(eval);
if (semnum < 0 || semnum >= semaptr->sem_nsems)
return(EINVAL);
if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
return(eval);
semaptr->sem_base[semnum].semval = real_arg.val;
semundo_clear(semid, semnum);
wakeup((caddr_t)semaptr);
break;
case SETALL:
if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W)))
return(eval);
if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
return(eval);
for (i = 0; i < semaptr->sem_nsems; i++) {
eval = copyin(&real_arg.array[i],
(caddr_t)&semaptr->sem_base[i].semval,
sizeof(real_arg.array[0]));
if (eval != 0)
break;
}
semundo_clear(semid, -1);
wakeup((caddr_t)semaptr);
break;
default:
return(EINVAL);
}
if (eval == 0)
p->p_retval[0] = rval;
return(eval);
}
#ifndef _SYS_SYSPROTO_H_
struct semget_args {
key_t key;
int nsems;
int semflg;
};
#endif
int
semget(p, uap)
struct proc *p;
register struct semget_args *uap;
{
int semid, eval;
int key = uap->key;
int nsems = uap->nsems;
int semflg = uap->semflg;
struct ucred *cred = p->p_ucred;
#ifdef SEM_DEBUG
printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
#endif
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) {
#ifdef SEM_DEBUG
printf("found public key\n");
#endif
if ((eval = ipcperm(cred, &sema[semid].sem_perm,
semflg & 0700)))
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_second;
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:
p->p_retval[0] = 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)
struct proc *p;
register struct semop_args *uap;
{
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
p->p_retval[0] = 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);
}
}
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