int __sched __down_interruptible(struct semaphore * sem)
{
int retval = 0;
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
__set_task_state(tsk, TASK_INTERRUPTIBLE);
add_wait_queue_exclusive(&sem->wait, &wait);
while (__sem_update_count(sem, -1) <= 0) {
if (signal_pending(current)) {
/*
* A signal is pending - give up trying.
* Set sem->count to 0 if it is negative,
* since we are no longer sleeping.
*/
__sem_update_count(sem, 0);
retval = -EINTR;
break;
}
schedule();
set_task_state(tsk, TASK_INTERRUPTIBLE);
}
remove_wait_queue(&sem->wait, &wait);
__set_task_state(tsk, TASK_RUNNING);
wake_up(&sem->wait);
return retval;
}
/*
* Note that when we come in to __down or __down_interruptible,
* we have already decremented count, but that decrement was
* ineffective since the result was < 0, and any negative value
* of count is equivalent to 0.
* Thus it is only when we decrement count from some value > 0
* that we have actually got the semaphore.
*/
void __sched __down(struct semaphore *sem)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
add_wait_queue_exclusive(&sem->wait, &wait);
/*
* Try to get the semaphore. If the count is > 0, then we've
* got the semaphore; we decrement count and exit the loop.
* If the count is 0 or negative, we set it to -1, indicating
* that we are asleep, and then sleep.
*/
while (__sem_update_count(sem, -1) <= 0) {
schedule();
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
}
remove_wait_queue(&sem->wait, &wait);
__set_task_state(tsk, TASK_RUNNING);
/*
* If there are any more sleepers, wake one of them up so
* that it can either get the semaphore, or set count to -1
* indicating that there are still processes sleeping.
*/
wake_up(&sem->wait);
}
int __sched
__down_failed_interruptible(struct semaphore *sem)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
long ret = 0;
#ifdef CONFIG_DEBUG_SEMAPHORE
printk("%s(%d): down failed(%p)\n",
tsk->comm, tsk->pid, sem);
#endif
tsk->state = TASK_INTERRUPTIBLE;
wmb();
add_wait_queue_exclusive(&sem->wait, &wait);
while (__sem_update_count(sem, -1) <= 0) {
if (signal_pending(current)) {
/*
* A signal is pending - give up trying.
* Set sem->count to 0 if it is negative,
* since we are no longer sleeping.
*/
__sem_update_count(sem, 0);
ret = -EINTR;
break;
}
schedule();
set_task_state(tsk, TASK_INTERRUPTIBLE);
}
remove_wait_queue(&sem->wait, &wait);
tsk->state = TASK_RUNNING;
wake_up(&sem->wait);
#ifdef CONFIG_DEBUG_SEMAPHORE
printk("%s(%d): down %s(%p)\n",
current->comm, current->pid,
(ret < 0 ? "interrupted" : "acquired"), sem);
#endif
return ret;
}
void __up(struct semaphore *sem)
{
/*
* Note that we incremented count in up() before we came here,
* but that was ineffective since the result was <= 0, and
* any negative value of count is equivalent to 0.
* This ends up setting count to 1, unless count is now > 0
* (i.e. because some other cpu has called up() in the meantime),
* in which case we just increment count.
*/
__sem_update_count(sem, 1);
wake_up(&sem->wait);
}
int __down_interruptible(struct semaphore * sem)
{
int retval = 0;
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
tsk->state = TASK_INTERRUPTIBLE;
add_wait_queue_exclusive(&sem->wait, &wait);
while (__sem_update_count(sem, -1) <= 0) {
if (signal_pending(current)) {
__sem_update_count(sem, 0);
retval = -EINTR;
break;
}
schedule();
tsk->state = TASK_INTERRUPTIBLE;
}
tsk->state = TASK_RUNNING;
remove_wait_queue(&sem->wait, &wait);
wake_up(&sem->wait);
return retval;
}
void __down(struct semaphore * sem)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
tsk->state = TASK_UNINTERRUPTIBLE;
add_wait_queue_exclusive(&sem->wait, &wait);
while (__sem_update_count(sem, -1) <= 0) {
schedule();
tsk->state = TASK_UNINTERRUPTIBLE;
}
remove_wait_queue(&sem->wait, &wait);
tsk->state = TASK_RUNNING;
wake_up(&sem->wait);
}
void __sched
__down_failed(struct semaphore *sem)
{
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
#ifdef CONFIG_DEBUG_SEMAPHORE
printk("%s(%d): down failed(%p)\n",
tsk->comm, tsk->pid, sem);
#endif
tsk->state = TASK_UNINTERRUPTIBLE;
wmb();
add_wait_queue_exclusive(&sem->wait, &wait);
/*
* Try to get the semaphore. If the count is > 0, then we've
* got the semaphore; we decrement count and exit the loop.
* If the count is 0 or negative, we set it to -1, indicating
* that we are asleep, and then sleep.
*/
while (__sem_update_count(sem, -1) <= 0) {
schedule();
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
}
remove_wait_queue(&sem->wait, &wait);
tsk->state = TASK_RUNNING;
/*
* If there are any more sleepers, wake one of them up so
* that it can either get the semaphore, or set count to -1
* indicating that there are still processes sleeping.
*/
wake_up(&sem->wait);
#ifdef CONFIG_DEBUG_SEMAPHORE
printk("%s(%d): down acquired(%p)\n",
tsk->comm, tsk->pid, sem);
#endif
}
static void __up(struct semaphore *sem)
{
__sem_update_count(sem, 1);
wake_up(&sem->wait);
}