static int lineevent_create()

in gpiolib-cdev.c [1707:1845]

• 108 lines of code
• 26 McCabe index (conditional complexity)

static int lineevent_create(struct gpio_device *gdev, void __user *ip)
{
	struct gpioevent_request eventreq;
	struct lineevent_state *le;
	struct gpio_desc *desc;
	struct file *file;
	u32 offset;
	u32 lflags;
	u32 eflags;
	int fd;
	int ret;
	int irq, irqflags = 0;

	if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
		return -EFAULT;

	offset = eventreq.lineoffset;
	lflags = eventreq.handleflags;
	eflags = eventreq.eventflags;

	desc = gpiochip_get_desc(gdev->chip, offset);
	if (IS_ERR(desc))
		return PTR_ERR(desc);

	/* Return an error if a unknown flag is set */
	if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
	    (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS))
		return -EINVAL;

	/* This is just wrong: we don't look for events on output lines */
	if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
	    (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
	    (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
		return -EINVAL;

	/* Only one bias flag can be set. */
	if (((lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE) &&
	     (lflags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN |
			GPIOHANDLE_REQUEST_BIAS_PULL_UP))) ||
	    ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) &&
	     (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)))
		return -EINVAL;

	le = kzalloc(sizeof(*le), GFP_KERNEL);
	if (!le)
		return -ENOMEM;
	le->gdev = gdev;
	get_device(&gdev->dev);

	if (eventreq.consumer_label[0] != '\0') {
		/* label is only initialized if consumer_label is set */
		le->label = kstrndup(eventreq.consumer_label,
				     sizeof(eventreq.consumer_label) - 1,
				     GFP_KERNEL);
		if (!le->label) {
			ret = -ENOMEM;
			goto out_free_le;
		}
	}

	ret = gpiod_request(desc, le->label);
	if (ret)
		goto out_free_le;
	le->desc = desc;
	le->eflags = eflags;

	linehandle_flags_to_desc_flags(lflags, &desc->flags);

	ret = gpiod_direction_input(desc);
	if (ret)
		goto out_free_le;

	blocking_notifier_call_chain(&desc->gdev->notifier,
				     GPIO_V2_LINE_CHANGED_REQUESTED, desc);

	irq = gpiod_to_irq(desc);
	if (irq <= 0) {
		ret = -ENODEV;
		goto out_free_le;
	}
	le->irq = irq;

	if (eflags & GPIOEVENT_REQUEST_RISING_EDGE)
		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
	if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE)
		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
	irqflags |= IRQF_ONESHOT;

	INIT_KFIFO(le->events);
	init_waitqueue_head(&le->wait);

	/* Request a thread to read the events */
	ret = request_threaded_irq(le->irq,
				   lineevent_irq_handler,
				   lineevent_irq_thread,
				   irqflags,
				   le->label,
				   le);
	if (ret)
		goto out_free_le;

	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
	if (fd < 0) {
		ret = fd;
		goto out_free_le;
	}

	file = anon_inode_getfile("gpio-event",
				  &lineevent_fileops,
				  le,
				  O_RDONLY | O_CLOEXEC);
	if (IS_ERR(file)) {
		ret = PTR_ERR(file);
		goto out_put_unused_fd;
	}

	eventreq.fd = fd;
	if (copy_to_user(ip, &eventreq, sizeof(eventreq))) {
		/*
		 * fput() will trigger the release() callback, so do not go onto
		 * the regular error cleanup path here.
		 */
		fput(file);
		put_unused_fd(fd);
		return -EFAULT;
	}

	fd_install(fd, file);

	return 0;

out_put_unused_fd:
	put_unused_fd(fd);
out_free_le:
	lineevent_free(le);
	return ret;
}