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    SubjectRe: [PATCH v4 07/19] PCI/MSI: Let pci_msi_get_domain use struct device's msi_domain
    Hi Marc,

    On Wed, Jul 15, 2015 at 01:16:41PM +0100, Marc Zyngier wrote:
    > Now that we can easily find which MSI domain a PCI device is
    > using, use dev_get_msi_domain as a way to retrieve the information.
    >
    > The original code is still used as a fallback.
    >
    > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
    > ---
    > drivers/pci/msi.c | 3 ++-
    > 1 file changed, 2 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
    > index ef4ec6e..c77fdaf 100644
    > --- a/drivers/pci/msi.c
    > +++ b/drivers/pci/msi.c
    > @@ -41,7 +41,8 @@ static struct irq_domain *pci_msi_get_domain(struct pci_dev *dev)
    > {
    > struct irq_domain *domain = NULL;
    >
    > - if (dev->bus->msi)
    > + domain = dev_get_msi_domain(&dev->dev);
    > + if (!domain && dev->bus->msi)
    > domain = dev->bus->msi->domain;
    > if (!domain)
    > domain = arch_get_pci_msi_domain(dev);

    I think this would be slightly easier to read as:

    struct irq_domain *domain;

    domain = dev_get_msi_domain(&dev->dev);
    if (domain)
    return domain;

    if (dev->bus->msi && (domain = dev->bus->msi->domain))
    return domain;

    return arch_get_pci_msi_domain(dev);

    I'm not a huge fan of assignments inside "if" conditions, and checkpatch
    might even complain about it, but it exposes the fallback order pretty well
    here. I guess we could also just repeat the dev->bus->msi->domain
    expression:

    if (dev->bus->msi && dev->bus->msi->domain)
    return dev->bus->msi->domain;

    We can at least get rid of the superfluous initialization of domain to
    NULL.

    Bjorn


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