static ssize_t adb_read()

in adb.c [714:770]

• 49 lines of code
• 14 McCabe index (conditional complexity)

static ssize_t adb_read(struct file *file, char __user *buf,
			size_t count, loff_t *ppos)
{
	int ret = 0;
	struct adbdev_state *state = file->private_data;
	struct adb_request *req;
	DECLARE_WAITQUEUE(wait, current);
	unsigned long flags;

	if (count < 2)
		return -EINVAL;
	if (count > sizeof(req->reply))
		count = sizeof(req->reply);

	req = NULL;
	spin_lock_irqsave(&state->lock, flags);
	add_wait_queue(&state->wait_queue, &wait);
	set_current_state(TASK_INTERRUPTIBLE);

	for (;;) {
		req = state->completed;
		if (req != NULL)
			state->completed = req->next;
		else if (atomic_read(&state->n_pending) == 0)
			ret = -EIO;
		if (req != NULL || ret != 0)
			break;
		
		if (file->f_flags & O_NONBLOCK) {
			ret = -EAGAIN;
			break;
		}
		if (signal_pending(current)) {
			ret = -ERESTARTSYS;
			break;
		}
		spin_unlock_irqrestore(&state->lock, flags);
		schedule();
		spin_lock_irqsave(&state->lock, flags);
	}

	set_current_state(TASK_RUNNING);
	remove_wait_queue(&state->wait_queue, &wait);
	spin_unlock_irqrestore(&state->lock, flags);
	
	if (ret)
		return ret;

	ret = req->reply_len;
	if (ret > count)
		ret = count;
	if (ret > 0 && copy_to_user(buf, req->reply, ret))
		ret = -EFAULT;

	kfree(req);
	return ret;
}