linux-kernel - Re: [PATCH v11 08/10] OF: PCI: Add support for parsing PCI host bridge resources from DT

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Message-ID: <541CCA36.8010606@gmail.com>
Date:	Fri, 19 Sep 2014 19:28:38 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Liviu Dudau <Liviu.Dudau@....com>
CC:	Arnd Bergmann <arnd@...db.de>, Rob Herring <robh+dt@...nel.org>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	Russell King <linux@....linux.org.uk>,
	linux-pci <linux-pci@...r.kernel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Tanmay Inamdar <tinamdar@....com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Sinan Kaya <okaya@...eaurora.org>,
	Jingoo Han <jg1.han@...sung.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Suravee Suthikulanit <suravee.suthikulpanit@....com>,
	linux-arch <linux-arch@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Device Tree ML <devicetree@...r.kernel.org>,
	LAKML <linux-arm-kernel@...ts.infradead.org>,
	Grant Likely <grant.likely@...aro.org>
Subject: Re: [PATCH v11 08/10] OF: PCI: Add support for parsing PCI host bridge
 resources from DT

On 09/19/2014 04:06 PM, Bjorn Helgaas wrote:
> On Thu, Sep 18, 2014 at 02:30:23AM +0100, Liviu Dudau wrote:
>> Provide a function to parse the PCI DT ranges that can be used to
>> create a pci_host_bridge structure together with its associated
>> bus.
>>
>> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
>> Cc: Arnd Bergmann <arnd@...db.de>
>> Cc: Grant Likely <grant.likely@...aro.org>
>> Cc: Rob Herring <robh+dt@...nel.org>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
>> ---

[...]

>> +int of_pci_get_host_bridge_resources(struct device_node *dev,
>> +			unsigned char busno, unsigned char bus_max,
>> +			struct list_head *resources, resource_size_t *io_base)
>> +{
>> +	struct resource *res;
>> +	struct resource *bus_range;
>> +	struct of_pci_range range;
>> +	struct of_pci_range_parser parser;
>> +	char range_type[4];
>> +	int err;
>> +
>> +	if (!io_base)
>> +		return -EINVAL;
>> +	*io_base = OF_BAD_ADDR;
>> +
>> +	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);

This function does a lot of kalloc's but there is not an easy way to
undo those allocations. Hot unplug of a host bridge or probe error
handling would leak memory.

You could pass in struct device and use the devm_ variant (also
addressing Bjorn's comment), but not having an uninit/remove function
make what clean-up drivers have to do error prone. For example, on
uninit a driver needs to call pci_free_resource_list.

Rob
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