linux-kernel - Re: [PATCH v2 02/18] usb: host: xhci-plat: Add clocks support

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Date:	Fri, 25 Apr 2014 15:20:49 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
Cc:	Mathias Nyman <mathias.nyman@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Jason Cooper <jason@...edaemon.net>,
	Andrew Lunn <andrew@...n.ch>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Lior Amsalem <alior@...vell.com>,
	Tawfik Bayouk <tawfik@...vell.com>, devicetree@...r.kernel.org,
	Nadav Haklai <nadavh@...vell.com>,
	Rob Herring <robh+dt@...nel.org>,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	Grant Likely <grant.likely@...aro.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 02/18] usb: host: xhci-plat: Add clocks support

On Fri, Apr 25, 2014 at 04:07:00PM +0200, Gregory CLEMENT wrote:
> +#if defined(CONFIG_HAVE_CLK)
> +static int try_enable_clk(struct platform_device *pdev)
> +{
> +	struct clk *clk = devm_clk_get(&pdev->dev, NULL);
> +
> +	/* Not all platforms have a clk so it is not an error if the clock
> +	   does not exists. */
> +	if (!IS_ERR(clk))
> +		if (clk_prepare_enable(clk))
> +			return  -ENODEV;
> +	return 0;
> +}
> +
> +static int try_disable_clk(struct platform_device *pdev)
> +{
> +	struct clk *clk = devm_clk_get(&pdev->dev, NULL);
> +
> +	/* Not all platforms have a clk so it is not an error if the clock
> +	   does not exists. */
> +	if (!IS_ERR(clk))
> +		clk_disable_unprepare(clk);
> +
> +	return 0;
> +}

OMG.

You do realise that clk_get() ref-counts against the module which
provided the clock, so this is akin to an explicit leaking module
ref-counts.

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