[PATCH v5 6/9] PCI: Drop references acquired by of_parse_phandle()

[Rob Herring]

On Mon, Aug 10, 2015 at 4:39 PM, Bjorn Helgaas <bhelgaas at google.com> wrote:
> [+cc Ben, Rob]
>
> On Tue, Aug 04, 2015 at 04:54:35PM -0500, Bjorn Helgaas wrote:
>> of_parse_phandle() returns a device_node pointer with the refcount
>> incremented.  We should dispose of this reference when we're finished.
>>
>> Drop the reference acquired by of_parse_phandle().
>
> I cc'd everybody who wrote or signed off on 0d5a6db3aa46 ("of: pci: add
> registry of MSI chips"), which added of_pci_find_msi_chip_by_node().
>
> The existing code (before this patch) looks wrong to me, but I'm not an OF
> person.

In general, how DT reference counting works is broken and difficult to
get right. It doesn't really matter for most cases anyway (as nodes
don't get removed). I cannot tell you whether this patch is right or
wrong just looking at the patch. It seems correct based on your
description.

Rob

>
>> Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
>> ---
>>  drivers/pci/host/pci-mvebu.c |    1 +
>>  drivers/pci/host/pci-xgene.c |    1 +
>>  2 files changed, 2 insertions(+)
>>
>> diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
>> index 70aa095..67ec5e1 100644
>> --- a/drivers/pci/host/pci-mvebu.c
>> +++ b/drivers/pci/host/pci-mvebu.c
>> @@ -879,6 +879,7 @@ static void mvebu_pcie_msi_enable(struct mvebu_pcie *pcie)
>>               return;
>>
>>       pcie->msi = of_pci_find_msi_chip_by_node(msi_node);
>> +     of_node_put(msi_node);
>>
>>       if (pcie->msi)
>>               pcie->msi->dev = &pcie->pdev->dev;
>> diff --git a/drivers/pci/host/pci-xgene.c b/drivers/pci/host/pci-xgene.c
>> index a9dfb70..4c2fb1f 100644
>> --- a/drivers/pci/host/pci-xgene.c
>> +++ b/drivers/pci/host/pci-xgene.c
>> @@ -514,6 +514,7 @@ static int xgene_pcie_msi_enable(struct pci_bus *bus)
>>       if (!bus->msi)
>>               return -ENODEV;
>>
>> +     of_node_put(msi_node);
>>       bus->msi->dev = &bus->dev;
>>       return 0;
>>  }
>>