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NetBSD/sys/kern/sysv_sem.c

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/*
* Implementation of SVID semaphores
*
* Author: Daniel Boulet
*
* This software is provided ``AS IS'' without any warranties of any kind.
*/
#ifdef SYSVSEM
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/sem.h>
#include <sys/malloc.h>
static int semctl(), semget(), semop(), semconfig();
int (*semcalls[])() = { semctl, semget, semop, semconfig };
int semtot = 0;
static struct proc *semlock_holder = NULL;
int
seminit()
{
register int i;
vm_offset_t whocares1, whocares2;
if ( sema == NULL ) {
panic("sema is NULL");
}
for ( i = 0; i < seminfo.semmni; i += 1 ) {
sema[i].sem_base = 0;
sema[i].sem_perm.mode = 0;
}
if ( semu == NULL ) {
panic("semu is NULL");
}
for ( i = 0; i < seminfo.semmnu; i += 1 ) {
register struct sem_undo *suptr = SEMU(i);
suptr->un_proc = NULL;
}
semu_list = NULL;
}
/*
* Entry point for all SEM calls
*/
struct semsys_args {
u_int which;
};
int
semsys(p, uap, retval)
struct proc *p;
struct semsys_args *uap;
int *retval;
{
while ( semlock_holder != NULL && semlock_holder != p ) {
/* printf("semaphore facility locked - sleeping ...\n"); */
sleep( (caddr_t)&semlock_holder, (PZERO - 4) );
}
if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
return (EINVAL);
return ((*semcalls[uap->which])(p, &uap[1], retval));
}
/*
* 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.
*/
struct semconfig_args {
semconfig_ctl_t flag;
};
int
semconfig(p, uap, retval)
struct proc *p;
struct semconfig_args *uap;
int *retval;
{
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;
}
*retval = 0;
return(eval);
}
/*
* Allocate a new sem_undo structure for a process
* (returns ptr to structure or NULL if no more room)
*/
struct sem_undo *
semu_alloc(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 += 1 ) {
/*
* Look for a free structure.
* Fill it in and return it if we find one.
*/
for ( i = 0; i < seminfo.semmnu; i += 1 ) {
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");
}
}
}
/*
* Adjust a particular entry for a particular proc
*/
int
semundo_adjust(register struct proc *p,struct sem_undo **supptr,int semid,int 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 ) {
/* printf("adjust: need to find suptr\n"); */
for ( suptr = semu_list; suptr != NULL; suptr = suptr->un_next ) {
if ( suptr->un_proc == p ) {
/* printf("adjust: found suptr @%08x\n",suptr); */
*supptr = suptr;
break;
}
}
if ( suptr == NULL ) {
if ( adjval == 0 ) {
return(0); /* Don't create it if it doesn't exist */
}
suptr = semu_alloc(p);
if ( suptr == NULL ) {
return(ENOSPC);
}
/* printf("adjust: allocated suptr @%08x\n",suptr); */
*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 += 1, sunptr += 1 ) {
if ( sunptr->un_id == semid && sunptr->un_num == semnum ) {
/* Found the right entry - adjust it */
if ( adjval == 0 ) {
sunptr->un_adjval = 0;
} else {
/* printf("adjust: %08x %d:%d(%d) += %d\n",suptr->un_proc,semid,semnum,sunptr->un_adjval,adjval); */
sunptr->un_adjval += adjval;
}
if ( sunptr->un_adjval == 0 ) {
/* printf("adjust: %08x deleting entry %d:%d\n",suptr->un_proc,semid,semnum); */
suptr->un_cnt -= 1;
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);
} else {
/* printf("adjust: %08x allocating entry %d as %d:%d(%d)\n",suptr->un_proc,suptr->un_cnt,semid,semnum,adjval); */
sunptr = &(suptr->un_ent[suptr->un_cnt]);
suptr->un_cnt += 1;
sunptr->un_adjval = adjval;
sunptr->un_id = semid; sunptr->un_num = semnum;
}
return(0);
}
void
semundo_clear(int semid,int 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 ) {
int advance = 1;
if ( sunptr->un_id == semid ) {
if ( semnum == -1 || sunptr->un_num == semnum ) {
/* printf("clear: %08x %d:%d(%d)\n",suptr->un_proc,semid,sunptr->un_num,sunptr->un_adjval); */
suptr->un_cnt -= 1;
if ( i < suptr->un_cnt ) {
suptr->un_ent[i] = suptr->un_ent[suptr->un_cnt];
advance = 0;
}
}
if ( semnum != -1 ) {
break;
}
}
if ( advance ) {
i += 1;
sunptr += 1;
}
}
}
}
struct semctl_args {
int semid;
int semnum;
int cmd;
union semun *arg;
};
int
semctl(p, uap, retval)
struct proc *p;
register struct semctl_args *uap;
int *retval;
{
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 ) {
/* printf("semid out of range (0<=%d<%d)\n",semid,seminfo.semmsl); */
return(EINVAL);
}
semaptr = &sema[semid];
if ( semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid) ) {
/* printf("invalid sequence number\n"); */
return(EINVAL);
}
if ( (semaptr->sem_perm.mode & SEM_ALLOC) == 0 ) {
/* printf("no such semaphore id\n"); */
return(EINVAL);
}
eval = 0;
rval = 0;
switch (cmd) {
case IPC_RMID:
if ( cred->cr_uid != 0
&& semaptr->sem_perm.cuid != cred->cr_uid
&& semaptr->sem_perm.uid != cred->cr_uid ) {
return(EPERM);
}
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 += 1 ) {
/* printf("0x%x = 0x%x; ",&sem[i],&sem[i + semaptr->sem_nsems]); */
sem[i] = sem[i + semaptr->sem_nsems];
}
/* printf("\n"); */
for ( i = 0; i < seminfo.semmni; i += 1 ) {
if ( (sema[i].sem_perm.mode & SEM_ALLOC)
&& sema[i].sem_base > semaptr->sem_base ) {
/* printf("sema[%d].sem_base was 0x%x",i,sema[i].sem_base); */
sema[i].sem_base -= semaptr->sem_nsems;
/* printf(", now 0x%x\n",sema[i].sem_base); */
}
}
semaptr->sem_perm.mode = 0;
/* Delete any undo entries for this semid */
semundo_clear(semid,-1);
/* Make sure that anybody who is waiting notices the deletion */
wakeup( (caddr_t)semaptr );
break;
case IPC_SET:
/* printf("IPC_SET\n"); */
if ( cred->cr_uid != 0
&& semaptr->sem_perm.cuid != cred->cr_uid
&& semaptr->sem_perm.uid != cred->cr_uid ) {
return(EPERM);
}
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.tv_sec;
break;
case IPC_STAT:
/* printf("IPC_STAT\n"); */
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_R, cred)) ) {
return(eval);
}
rval = 0;
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:
/* printf("GETNCNT(%d)\n",semnum); */
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_R, cred)) ) {
return(eval);
}
if ( semnum < 0 || semnum >= semaptr->sem_nsems ) return(EINVAL);
rval = semaptr->sem_base[semnum].semncnt;
break;
case GETPID:
/* printf("GETPID(%d)\n",semnum); */
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_R, cred)) ) {
return(eval);
}
if ( semnum < 0 || semnum >= semaptr->sem_nsems ) return(EINVAL);
rval = semaptr->sem_base[semnum].sempid;
break;
case GETVAL:
/* printf("GETVAL(%d)\n",semnum); */
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_R, cred)) ) {
return(eval);
}
if ( semnum < 0 || semnum >= semaptr->sem_nsems ) return(EINVAL);
rval = semaptr->sem_base[semnum].semval;
break;
case GETALL:
/* printf("GETALL\n"); */
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_R, cred)) ) {
return(eval);
}
rval = 0;
if ( (eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0 ) {
/* printf("initial copyin failed (addr=0x%x)\n",arg); */
return(eval);
}
/* printf("%d semaphores\n",semaptr->sem_nsems); */
for ( i = 0; i < semaptr->sem_nsems; i += 1 ) {
/* printf("copyout to 0x%x\n",&real_arg.array[i]); */
eval =
copyout((caddr_t)&semaptr->sem_base[i].semval,
&real_arg.array[i],
sizeof(real_arg.array[0]));
if ( eval != 0 ) {
/* printf("copyout to 0x%x failed\n",&real_arg.array[i]); */
break;
}
}
break;
case GETZCNT:
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_R, cred)) ) {
return(eval);
}
/* printf("GETZCNT(%d)\n",semnum); */
if ( semnum < 0 || semnum >= semaptr->sem_nsems ) return(EINVAL);
rval = semaptr->sem_base[semnum].semzcnt;
break;
case SETVAL:
#ifdef SEM_DEBUG
printf("SETVAL(%d)\n",semnum);
#endif
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_W, cred)) ) {
return(eval);
}
if ( semnum < 0 || semnum >= semaptr->sem_nsems ) return(EINVAL);
rval = 0;
if ( (eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0 ) {
return(eval);
}
#ifdef SEM_DEBUG
printf("semaptr=%x, sem_base=%x, semptr=%x, oldval=%d, ",
semaptr,semaptr->sem_base,&semaptr->sem_base[semnum],semaptr->sem_base[semnum].semval);
#endif
semaptr->sem_base[semnum].semval = real_arg.val;
#ifdef SEM_DEBUG
printf(" newval=%d\n", semaptr->sem_base[semnum].semval);
#endif
semundo_clear(semid,semnum);
wakeup( (caddr_t)semaptr ); /* somebody else might care */
break;
case SETALL:
/* printf("SETALL\n"); */
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_W, cred)) ) {
return(eval);
}
rval = 0;
if ( (eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0 ) {
return(eval);
}
for ( i = 0; i < semaptr->sem_nsems; i += 1 ) {
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 ); /* somebody else might care */
break;
default:
/* printf("invalid command %d\n",cmd); */
return(EINVAL);
}
if ( eval == 0 ) {
*retval = rval;
}
return(eval);
}
struct semget_args {
key_t key;
int nsems;
int semflg;
};
int
semget(p, uap, retval)
struct proc *p;
register struct semget_args *uap;
int *retval;
{
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 ) {
#ifdef SEM_DEBUG
printf("private key\n");
#endif
semid = seminfo.semmni;
} else {
for ( semid = 0; semid < seminfo.semmni; semid += 1 ) {
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 = ipcaccess(&sema[semid].sem_perm, semflg & 0700, cred)) ) {
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);
}
} else {
#ifdef SEM_DEBUG
printf("didn't find public key\n");
#endif
}
}
if ( semid == seminfo.semmni ) {
#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 += 1 ) {
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; /* avoid semid overflows */
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);
}
}
*retval = IXSEQ_TO_IPCID(semid,sema[semid].sem_perm); /* Convert to one origin */
return(0);
}
struct semop_args {
int semid;
struct sembuf *sops;
int nsops;
};
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 all_ok, 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 ) {
/* printf("semid out of range (0<=%d<%d)\n",semid,seminfo.semmsl); */
return(EINVAL);
}
semaptr = &sema[semid];
if ( (semaptr->sem_perm.mode & SEM_ALLOC) == 0 ) {
/* printf("no such semaphore id\n"); */
return(EINVAL);
}
if ( semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid) ) {
/* printf("invalid sequence number\n"); */
return(EINVAL);
}
if ( (eval = ipcaccess(&semaptr->sem_perm, IPC_W, cred)) ) {
#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;
while (1) {
do_wakeup = 0;
for ( i = 0; i < nsops; i += 1 ) {
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 ) {
/*
* 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 += 1 ) {
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 += 1;
} else {
semptr->semncnt += 1;
}
#ifdef SEM_DEBUG
printf("semop: good night!\n");
#endif
eval = tsleep( (caddr_t)semaptr, (PZERO - 4) | PCATCH, "sem wait", 0 );
#ifdef SEM_DEBUG
printf("semop: good morning (eval=%d)!\n",eval);
#endif
suptr = NULL; /* The sem_undo may have been reallocated */
if ( eval != 0 ) {
/* printf("semop: interrupted system call\n"); */
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) ) {
/* printf("semaphore id deleted\n"); */
/* 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 -= 1;
} else {
semptr->semncnt -= 1;
}
} else {
/*
* Yes ... we're done.
* Process any SEM_UNDO requests.
*/
if ( do_undos ) {
for ( i = 0; i < nsops; i += 1 ) {
/* We only need to deal with SEM_UNDO's for non-zero op's */
int adjval;
if ( (sops[i].sem_flg & SEM_UNDO) != 0 && (adjval = sops[i].sem_op) != 0 ) {
eval = semundo_adjust(p,&suptr,semid,sops[i].sem_num,-adjval);
if ( eval != 0 ) {
/*
* 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 -= 1 ) {
if ( (sops[i].sem_flg & SEM_UNDO) != 0 && (adjval = sops[i].sem_op) != 0 ) {
if ( semundo_adjust(p,&suptr,semid,sops[j].sem_num,adjval) != 0 ) {
/* This is impossible! */
panic("semop - can't undo undos");
}
}
} /* loop backwards through sops */
for ( j = 0; j < nsops; j += 1 ) {
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 );
} /* semundo_adjust failed */
} /* if ( SEM_UNDO && adjval != 0 ) */
} /* loop through the sops */
} /* if ( do_undos ) */
/* We're definitely done - set the sempid's */
for ( i = 0; i < nsops; i += 1 ) {
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);
}
}
panic("semop: how did we get here???");
}
/*
* Go through the undo structures for this process and apply the
* adjustments to semaphores.
*/
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
sleep( (caddr_t)&semlock_holder, (PZERO - 4) );
}
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 ) {
#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 += 1 ) {
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;
}
/* printf("semval now %d\n",semaptr->sem_base[semnum].semval); */
#ifdef SEM_WAKEUP
sem_wakeup((caddr_t)semaptr); /* A little sloppy (we should KNOW if anybody is waiting). */
#else
wakeup((caddr_t)semaptr); /* A little sloppy (we should KNOW if anybody is waiting). */
#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;
/* Done. */
break;
}
}
/*
* 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 );
}
}
#endif
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