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.
Nice to get rid of the list traversal.
> + return NULL;
> +
> + root = acpi_driver_data(device);
> +
> + return root;
> }
> EXPORT_SYMBOL_GPL(acpi_pci_find_root);
>
>
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