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    SubjectRe: [PATCH 2/3] ACPI: Remove platform devices from a bus on removal
    On Wed, Mar 22, 2017 at 06:33:24PM +0100, Joerg Roedel wrote:
    > From: Joerg Roedel <jroedel@suse.de>
    >
    > The function acpi_bus_attach() creates platform_devices if
    > this is specified by the firmware. But in acpi_bus_trim()
    > these devices are not removed, leaving a dangling reference
    > to the parent device.
    >
    > In the case of a PCI root-bus, this results in the
    > host_bridge device not being released on hot-remove.
    >
    > Fix it by scanning the list of platform_devices for devices
    > to be removed with the bus.
    >
    > Signed-off-by: Joerg Roedel <jroedel@suse.de>
    > ---
    > drivers/acpi/scan.c | 26 ++++++++++++++++++++++++++
    > 1 file changed, 26 insertions(+)
    >
    > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
    > index 1926918..b07518b 100644
    > --- a/drivers/acpi/scan.c
    > +++ b/drivers/acpi/scan.c
    > @@ -13,6 +13,7 @@
    > #include <linux/dmi.h>
    > #include <linux/nls.h>
    > #include <linux/dma-mapping.h>
    > +#include <linux/platform_device.h>
    >
    > #include <asm/pgtable.h>
    >
    > @@ -1928,6 +1929,25 @@ int acpi_bus_scan(acpi_handle handle)
    > EXPORT_SYMBOL(acpi_bus_scan);
    >
    > /**
    > + * acpi_bus_trim_platform_device - Check and remove a platform device
    > + * from a bus
    > + * @dev: Platform device to check
    > + * @data: pointer to the acpi_device to check dev against
    > + *
    > + * Checks whether the platform_device dev belongs to the acpi_device
    > + * data and unregisters dev if it matches.
    > + */
    > +static int acpi_bus_trim_platform_device(struct device *dev, void *data)
    > +{
    > + struct acpi_device *adev = data;
    > +
    > + if (dev->fwnode == acpi_fwnode_handle(adev))
    > + platform_device_unregister(to_platform_device(dev));
    > +
    > + return 0;
    > +}
    > +
    > +/**
    > * acpi_bus_trim - Detach scan handlers and drivers from ACPI device objects.
    > * @adev: Root of the ACPI namespace scope to walk.
    > *
    > @@ -1950,6 +1970,12 @@ void acpi_bus_trim(struct acpi_device *adev)
    > } else {
    > device_release_driver(&adev->dev);
    > }
    > +
    > + /* Remove platform devices from the bus */
    > + if (adev->pnp.type.platform_id)

    This patch cases that dock_notify() is broken in find_dock_station()
    because the dock_station platform device was removed.

    If anyone wants to apply this patch, then the dock device should be
    excluded:

    + if (is_dock_device(adev) && adev->pnp.type.platform_id)

    > + bus_for_each_dev(&platform_bus_type, NULL, adev,
    > + acpi_bus_trim_platform_device);
    > +
    > /*
    > * Most likely, the device is going away, so put it into D3cold before
    > * that.

    Thanks a lot!
    Joey Lee

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