asmlinkage int sys_semop (int semid, struct sembuf *tsops, unsigned nsops)
{
int id, size, error = -EINVAL;
struct semid_ds *sma;
struct sembuf sops[SEMOPM], *sop;
struct sem_undo *un;
int undos = 0, decrease = 0, alter = 0;
struct sem_queue queue;
lock_kernel();
if (nsops < 1 || semid < 0)
goto out;
error = -E2BIG;
if (nsops > SEMOPM)
goto out;
error = -EFAULT;
if (copy_from_user (sops, tsops, nsops * sizeof(*tsops)))
goto out;
id = (unsigned int) semid % SEMMNI;
error = -EINVAL;
if ((sma = semary[id]) == IPC_UNUSED || sma == IPC_NOID)
goto out;
error = -EIDRM;
if (sma->sem_perm.seq != (unsigned int) semid / SEMMNI)
goto out;
error = -EFBIG;
for (sop = sops; sop < sops + nsops; sop++) {
if (sop->sem_num >= sma->sem_nsems)
goto out;
if (sop->sem_flg & SEM_UNDO)
undos++;
if (sop->sem_op < 0)
decrease = 1;
if (sop->sem_op > 0)
alter = 1;
}
alter |= decrease;
error = -EACCES;
if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
goto out;
if (undos) {
/* Make sure we have an undo structure
* for this process and this semaphore set.
*/
for (un = current->semundo; un; un = un->proc_next)
if (un->semid == semid)
break;
if (!un) {
size = sizeof(struct sem_undo) + sizeof(short)*sma->sem_nsems;
un = (struct sem_undo *) kmalloc(size, GFP_ATOMIC);
if (!un) {
error = -ENOMEM;
goto out;
}
memset(un, 0, size);
un->semadj = (short *) &un[1];
un->semid = semid;
un->proc_next = current->semundo;
current->semundo = un;
un->id_next = sma->undo;
sma->undo = un;
}
} else
un = NULL;
error = try_atomic_semop (sma, sops, nsops, un, current->pid, 0);
if (error <= 0)
goto update;
/* We need to sleep on this operation, so we put the current
* task into the pending queue and go to sleep.
*/
queue.sma = sma;
queue.sops = sops;
queue.nsops = nsops;
queue.undo = un;
queue.pid = current->pid;
queue.alter = decrease;
current->semsleeping = &queue;
if (alter)
append_to_queue(sma ,&queue);
else
prepend_to_queue(sma ,&queue);
for (;;) {
queue.status = -EINTR;
queue.sleeper = NULL;
interruptible_sleep_on(&queue.sleeper);
/*
* If queue.status == 1 we where woken up and
* have to retry else we simply return.
* If an interrupt occurred we have to clean up the
* queue
*
*/
if (queue.status == 1)
{
error = try_atomic_semop (sma, sops, nsops, un,
current->pid,0);
if (error <= 0)
break;
} else {
error = queue.status;;
if (queue.prev) /* got Interrupt */
break;
/* Everything done by update_queue */
current->semsleeping = NULL;
goto out;
}
}
current->semsleeping = NULL;
remove_from_queue(sma,&queue);
update:
if (alter)
update_queue (sma);
out:
unlock_kernel();
return error;
}
asmlinkage long sys_semtimedop (int semid, struct sembuf *tsops,
unsigned nsops, const struct timespec *timeout)
{
int error = -EINVAL;
struct sem_array *sma;
struct sembuf fast_sops[SEMOPM_FAST];
struct sembuf* sops = fast_sops, *sop;
struct sem_undo *un;
int undos = 0, decrease = 0, alter = 0;
struct sem_queue queue;
unsigned long jiffies_left = 0;
if (nsops < 1 || semid < 0)
return -EINVAL;
if (nsops > sc_semopm)
return -E2BIG;
if(nsops > SEMOPM_FAST) {
sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL);
if(sops==NULL)
return -ENOMEM;
}
if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
error=-EFAULT;
goto out_free;
}
if (timeout) {
struct timespec _timeout;
if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
error = -EFAULT;
goto out_free;
}
if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
_timeout.tv_nsec >= 1000000000L) {
error = -EINVAL;
goto out_free;
}
jiffies_left = timespec_to_jiffies(&_timeout);
}
sma = sem_lock(semid);
error=-EINVAL;
if(sma==NULL)
goto out_free;
error = -EIDRM;
if (sem_checkid(sma,semid))
goto out_unlock_free;
error = -EFBIG;
for (sop = sops; sop < sops + nsops; sop++) {
if (sop->sem_num >= sma->sem_nsems)
goto out_unlock_free;
if (sop->sem_flg & SEM_UNDO)
undos++;
if (sop->sem_op < 0)
decrease = 1;
if (sop->sem_op > 0)
alter = 1;
}
alter |= decrease;
error = -EACCES;
if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
goto out_unlock_free;
if (undos) {
/* Make sure we have an undo structure
* for this process and this semaphore set.
*/
un=current->semundo;
while(un != NULL) {
if(un->semid==semid)
break;
if(un->semid==-1)
un=freeundos(sma,un);
else
un=un->proc_next;
}
if (!un) {
error = alloc_undo(sma,&un,semid,alter);
if(error)
goto out_free;
}
} else
un = NULL;
error = try_atomic_semop (sma, sops, nsops, un, current->tgid, 0);
if (error <= 0)
goto update;
/* We need to sleep on this operation, so we put the current
* task into the pending queue and go to sleep.
*/
queue.sma = sma;
queue.sops = sops;
queue.nsops = nsops;
queue.undo = un;
queue.pid = current->tgid;
queue.alter = decrease;
queue.id = semid;
if (alter)
append_to_queue(sma ,&queue);
else
prepend_to_queue(sma ,&queue);
current->semsleeping = &queue;
for (;;) {
struct sem_array* tmp;
queue.status = -EINTR;
queue.sleeper = current;
current->state = TASK_INTERRUPTIBLE;
sem_unlock(semid);
if (timeout)
jiffies_left = schedule_timeout(jiffies_left);
else
schedule();
tmp = sem_lock(semid);
if(tmp==NULL) {
if(queue.prev != NULL)
BUG();
current->semsleeping = NULL;
error = -EIDRM;
goto out_free;
}
/*
* If queue.status == 1 we where woken up and
* have to retry else we simply return.
* If an interrupt occurred we have to clean up the
* queue
*
*/
if (queue.status == 1)
{
error = try_atomic_semop (sma, sops, nsops, un,
current->tgid, 0);
if (error <= 0)
break;
} else {
error = queue.status;
if (error == -EINTR && timeout && jiffies_left == 0)
error = -EAGAIN;
if (queue.prev) /* got Interrupt */
break;
/* Everything done by update_queue */
current->semsleeping = NULL;
goto out_unlock_free;
}
}
current->semsleeping = NULL;
remove_from_queue(sma,&queue);
update:
if (alter)
update_queue (sma);
out_unlock_free:
sem_unlock(semid);
out_free:
if(sops != fast_sops)
kfree(sops);
return error;
}
