linux-kernel - Re: [PATCH v20 06/10] fpga: add fpga bridge framework

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Date:   Mon, 17 Oct 2016 15:25:15 -0500
From:   atull <atull@...nsource.altera.com>
To:     Rob Herring <robh+dt@...nel.org>
CC:     Frank Rowand <frowand.list@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Moritz Fischer <moritz.fischer@...us.com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Jon Masters <jcm@...hat.com>,
        Michal Simek <michal.simek@...inx.com>,
        Jonathan Corbet <corbet@....net>,
        "Cyril Chemparathy" <cyril.chemparathy@...inx.com>,
        Matthew Gerlach <mgerlach@...nsource.altera.com>,
        Dinh Nguyen <dinguyen@...nsource.altera.com>,
        <devicetree@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <delicious.quinoa@...il.com>
Subject: Re: [PATCH v20 06/10] fpga: add fpga bridge framework

On Mon, 17 Oct 2016, Alan Tull wrote:

> +/**
> + * of_fpga_bridge_get - get an exclusive reference to a fpga bridge
> + *
> + * @np: node pointer of a FPGA bridge
> + * @info: fpga image specific information
> + *
> + * Return fpga_bridge struct if successful.
> + * Return -EBUSY if someone already has a reference to the bridge.
> + * Return -ENODEV if @np is not a FPGA Bridge.
> + */
> +struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
> +				       struct fpga_image_info *info)
> +
> +{
> +	struct device *dev;
> +	struct fpga_bridge *bridge;
> +	int ret = -ENODEV;
> +
> +	of_node_get(np);

I thought I had fixed this.  This of_node_get is unmatched,
never called in fpga_bridge_put.  And it's not necessary
since class_find_device will do kobject_get on the child
device anyway.  So I should remove this of_node_get
and the of_node_put below.

> +
> +	dev = class_find_device(fpga_bridge_class, NULL, np,
> +				fpga_bridge_of_node_match);
> +	if (!dev)
> +		goto err_dev;
> +
> +	bridge = to_fpga_bridge(dev);
> +	if (!bridge)
> +		goto err_dev;
> +
> +	bridge->info = info;
> +
> +	if (!mutex_trylock(&bridge->mutex)) {
> +		ret = -EBUSY;
> +		goto err_dev;
> +	}
> +
> +	if (!try_module_get(dev->parent->driver->owner))
> +		goto err_ll_mod;
> +
> +	dev_dbg(&bridge->dev, "get\n");
> +
> +	return bridge;
> +
> +err_ll_mod:
> +	mutex_unlock(&bridge->mutex);
> +err_dev:
> +	put_device(dev);
> +	of_node_put(np);

Remove of_node_put.

> +	return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(of_fpga_bridge_get);
> +
> +/**
> + * fpga_bridge_put - release a reference to a bridge
> + *
> + * @bridge: FPGA bridge
> + */
> +void fpga_bridge_put(struct fpga_bridge *bridge)
> +{
> +	dev_dbg(&bridge->dev, "put\n");
> +
> +	bridge->info = NULL;
> +	module_put(bridge->dev.parent->driver->owner);
> +	mutex_unlock(&bridge->mutex);
> +	put_device(&bridge->dev);
> +}
> +EXPORT_SYMBOL_GPL(fpga_bridge_put);