linux-kernel - Re: [PATCH v2 2/2] usb: ulpi: Call of_node

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Date:   Tue, 25 Jan 2022 11:18:09 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Sean Anderson <sean.anderson@...o.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] usb: ulpi: Call of_node_put correctly

On Mon, Jan 24, 2022 at 12:33:44PM -0500, Sean Anderson wrote:
> of_node_put should always be called on device nodes gotten from
> of_get_*. Additionally, it should only be called after there are no
> remaining users. To address the first issue, call of_node_put if later
> steps in ulpi_register fail. To address the latter, call of_node_put
> only after calling device_unregister.

This looks like a fix, but you don't have the fix tag.

> Signed-off-by: Sean Anderson <sean.anderson@...o.com>
> ---
> 
> Changes in v2:
> - New
> 
>  drivers/usb/common/ulpi.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/common/ulpi.c b/drivers/usb/common/ulpi.c
> index 87deb514eb78..c6ba72544f2b 100644
> --- a/drivers/usb/common/ulpi.c
> +++ b/drivers/usb/common/ulpi.c
> @@ -301,11 +301,11 @@ static int ulpi_register(struct device *dev, struct ulpi *ulpi)
>  
>  	ret = ulpi_read_id(ulpi);
>  	if (ret)
> -		return ret;
> +		goto err;
>  
>  	ret = device_register(&ulpi->dev);
>  	if (ret)
> -		return ret;
> +		goto err;

I think there is another bug in the code here. Missing put_device().

If you first fix that, you should then be able to call
fwnode_handle_put() (instead of of_node_put()) from
ulpi_dev_release(), and that should cover all cases.

>  	root = debugfs_create_dir(dev_name(dev), ULPI_ROOT);
>  	debugfs_create_file("regs", 0444, root, ulpi, &ulpi_regs_ops);
> @@ -314,6 +314,10 @@ static int ulpi_register(struct device *dev, struct ulpi *ulpi)
>  		ulpi->id.vendor, ulpi->id.product);
>  
>  	return 0;
> +
> +err:
> +	of_node_put(ulpi->dev.of_node);
> +	return ret;

So no need for that.

>  }
>  
>  /**
> @@ -357,8 +361,8 @@ void ulpi_unregister_interface(struct ulpi *ulpi)
>  {
>  	debugfs_remove_recursive(debugfs_lookup(dev_name(&ulpi->dev),
>  						ULPI_ROOT));
> -	of_node_put(ulpi->dev.of_node);
>  	device_unregister(&ulpi->dev);
> +	of_node_put(ulpi->dev.of_node);
>  }

And here you can just remove that of_node_put() call.

thanks,

-- 
heikki