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#include "drmP.h"
void drm_bo_init_lock(struct drm_bo_lock *lock)
{
DRM_INIT_WAITQUEUE(&lock->queue);
atomic_set(&lock->write_lock_pending, 0);
atomic_set(&lock->readers, 0);
}
void drm_bo_read_unlock(struct drm_bo_lock *lock)
{
if (unlikely(atomic_add_negative(-1, &lock->readers) == 0))
BUG();
if (atomic_read(&lock->readers) == 0)
wake_up_interruptible(&lock->queue);
}
int drm_bo_read_lock(struct drm_bo_lock *lock)
{
while( unlikely(atomic_read(&lock->write_lock_pending) != 0)) {
int ret;
ret = wait_event_interruptible
(lock->queue,
atomic_read(&lock->write_lock_pending) == 0);
if (ret)
return -EAGAIN;
}
while( unlikely (!atomic_add_unless(&lock->readers, 1, -1))) {
int ret;
ret = wait_event_interruptible
(lock->queue,
atomic_add_unless(&lock->readers, 1, -1));
if (ret)
return -EAGAIN;
}
return 0;
}
static int __drm_bo_write_unlock(struct drm_bo_lock *lock)
{
if (unlikely(atomic_cmpxchg(&lock->readers, -1, 0) != -1))
return -EINVAL;
if (unlikely(atomic_cmpxchg(&lock->write_lock_pending, 1, 0) != 1))
return -EINVAL;
wake_up_interruptible(&lock->queue);
return 0;
}
static void drm_bo_write_lock_remove(struct drm_file *file_priv,
struct drm_user_object *item)
{
struct drm_bo_lock *lock =
container_of(item, struct drm_bo_lock, base);
int ret;
ret = __drm_bo_write_unlock(lock);
BUG_ON(ret);
}
int drm_bo_write_lock(struct drm_bo_lock *lock, struct drm_file *file_priv)
{
int ret = 0;
struct drm_device *dev;
if (unlikely(atomic_cmpxchg(&lock->write_lock_pending, 0, 1) != 0))
return -EINVAL;
while(unlikely(atomic_cmpxchg(&lock->readers, 0, -1) != 0)) {
ret = wait_event_interruptible
(lock->queue,
atomic_cmpxchg(&lock->readers, 0, -1) == 0);
if (ret) {
atomic_set(&lock->write_lock_pending, 0);
wake_up_interruptible(&lock->queue);
return -EAGAIN;
}
}
dev = file_priv->head->dev;
mutex_lock(&dev->struct_mutex);
ret = drm_add_user_object(file_priv, &lock->base, 0);
lock->base.remove = &drm_bo_write_lock_remove;
lock->base.type = drm_lock_type;
if (ret)
(void) __drm_bo_write_unlock(lock);
mutex_unlock(&dev->struct_mutex);
return ret;
}
int drm_bo_write_unlock(struct drm_bo_lock *lock, struct drm_file *file_priv)
{
return drm_user_object_unref(file_priv, lock->base.hash.key,
drm_lock_type);
}
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