static ssize_t counter_chrdev_read()

in counter-chrdev.c [57:93]

• 31 lines of code
• 11 McCabe index (conditional complexity)

static ssize_t counter_chrdev_read(struct file *filp, char __user *buf,
				   size_t len, loff_t *f_ps)
{
	struct counter_device *const counter = filp->private_data;
	int err;
	unsigned int copied;

	if (!counter->ops)
		return -ENODEV;

	if (len < sizeof(struct counter_event))
		return -EINVAL;

	do {
		if (kfifo_is_empty(&counter->events)) {
			if (filp->f_flags & O_NONBLOCK)
				return -EAGAIN;

			err = wait_event_interruptible(counter->events_wait,
					!kfifo_is_empty(&counter->events) ||
					!counter->ops);
			if (err < 0)
				return err;
			if (!counter->ops)
				return -ENODEV;
		}

		if (mutex_lock_interruptible(&counter->events_out_lock))
			return -ERESTARTSYS;
		err = kfifo_to_user(&counter->events, buf, len, &copied);
		mutex_unlock(&counter->events_out_lock);
		if (err < 0)
			return err;
	} while (!copied);

	return copied;
}