On Wed, 19 Sep 2012 16:03:27 -0600
Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> On Tue, Sep 18, 2012 at 12:23 AM, Taku Izumi <izumi.taku@xxxxxxxxxxxxxx> wrote:
> >
> > This patch changes the implementation of acpi_pci_find_root().
> >
> > We can access acpi_pci_root without scanning acpi_pci_roots list.
> > If hostbridge hotplug is supported, acpi_pci_roots list will be
> > protected by mutex. We should not access acpi_pci_roots list
> > if preventable to lessen deadlock risk.
> >
> > Signed-off-by: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
> > ---
> > drivers/acpi/pci_root.c | 13 ++++++++-----
> > 1 file changed, 8 insertions(+), 5 deletions(-)
> >
> > Index: Bjorn-next-0903/drivers/acpi/pci_root.c
> > ===================================================================
> > --- Bjorn-next-0903.orig/drivers/acpi/pci_root.c
> > +++ Bjorn-next-0903/drivers/acpi/pci_root.c
> > @@ -265,12 +265,15 @@ static acpi_status acpi_pci_osc_support(
> > struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
> > {
> > struct acpi_pci_root *root;
> > + struct acpi_device *device;
> >
> > - list_for_each_entry(root, &acpi_pci_roots, node) {
> > - if (root->device->handle == handle)
> > - return root;
> > - }
> > - return NULL;
> > + if (acpi_bus_get_device(handle, &device) ||
> > + acpi_match_device_ids(device, root_device_ids))
>
> What's the purpose of the acpi_match_device_ids() check? It's not
> obvious, so worth calling it out in the changelog, and maybe even a
> comment in the code.
My intention is to reject acpi_handle which doesn't represent
hostbrige. I think this is reasonable...
Best regards,
Taku Izumi
>
> Nice to get rid of the list traversal.
>
> > + return NULL;
> > +
> > + root = acpi_driver_data(device);
> > +
> > + return root;
> > }
> > EXPORT_SYMBOL_GPL(acpi_pci_find_root);
> >
> >
>
--
Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
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