Re: [PATCH 2/5] driver core: separate function to shutdown one device

[Bart Van Assche <bvanassche@acm.org>]

On 3/11/26 10:12 AM, David Jeffery wrote:
> +static void shutdown_one_device(struct device *dev)
> +{
> +	/* hold lock to avoid race with probe/release */
> +	if (dev->parent && dev->bus && dev->bus->need_parent_lock)
> +		device_lock(dev->parent);
> +	device_lock(dev);
> +
> +	/* Don't allow any more runtime suspends */
> +	pm_runtime_get_noresume(dev);
> +	pm_runtime_barrier(dev);
> +
> +	if (dev->class && dev->class->shutdown_pre) {
> +		if (initcall_debug)
> +			dev_info(dev, "shutdown_pre\n");
> +		dev->class->shutdown_pre(dev);
> +	}
> +	if (dev->bus && dev->bus->shutdown) {
> +		if (initcall_debug)
> +			dev_info(dev, "shutdown\n");
> +		dev->bus->shutdown(dev);
> +	} else if (dev->driver && dev->driver->shutdown) {
> +		if (initcall_debug)
> +			dev_info(dev, "shutdown\n");
> +		dev->driver->shutdown(dev);
> +	}
> +
> +	device_unlock(dev);
> +	if (dev->parent && dev->bus && dev->bus->need_parent_lock)
> +		device_unlock(dev->parent);
> +
> +	put_device(dev->parent);
> +	put_device(dev);
> +}

Please keep the following code in the caller:

	if (dev->parent && dev->bus && dev->bus->need_parent_lock)
		device_lock(dev->parent);

	if (dev->parent && dev->bus && dev->bus->need_parent_lock)
		device_unlock(dev->parent);

	put_device(dev->parent);
	put_device(dev);

Additionally, please make sure that the caller is made compatible with
lock context analysis (see also
https://lore.kernel.org/all/20250206181711.1902989-1-elver@google.com/).
All that is required to make this code compatible with lock context
analysis is to organize it as follows:

	if (dev->parent && dev->bus && dev->bus->need_parent_lock) {
		device_lock(dev->parent);
		shutdown_one_device(dev);
		device_unlock(dev->parent);
	} else {
		shutdown_one_device(dev);
	}

Thanks,

Bart.