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    SubjectRe: [PATCH 32/36] driver core: Introduce device_move(): move a device to a new parent.
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    Hi Greg,

    > > > > > Provide a function device_move() to move a device to a new parent device. Add
    > > > > > auxilliary functions kobject_move() and sysfs_move_dir().
    > > > > > kobject_move() generates a new uevent of type KOBJ_MOVE, containing the
    > > > > > previous path (DEVPATH_OLD) in addition to the usual values. For this, a new
    > > > > > interface kobject_uevent_env() is created that allows to add further
    > > > > > environmental data to the uevent at the kobject layer.
    > > > >
    > > > > has this one been tested? I don't get it working. I always get an EINVAL
    > > > > when trying to move the TTY device of a Bluetooth RFCOMM link around.
    > > >
    > > > I relied on Cornelia to test this. I think some s390 patches depend on
    > > > this change, right?
    > >
    > > my pre-condition is that the TTY device has no parent and then we move
    > > it to a Bluetooth ACL link as child. This however is not working or the
    > > TTY change to use device instead of class_device has broken something.
    >
    > Hm, I don't think the class_device stuff has broken anything, but if you
    > think so, please let me know.

    I was checking why device_move() fails and it seems that the check for
    is_registered is the problem here.

    if (!device_is_registered(dev)) {
    error = -EINVAL;
    goto out;
    }

    The ACL link has been attached to the Bluetooth bus, but for some reason
    it still thinks that it is unregistered. Is this check really needed. I
    think it should be possible to also move devices that are not part of a
    bus, yet. And removing that check makes it work for me.

    And btw. I can't see any s390 patches that are using device_move() at
    the moment.

    > > > > And shouldn't device_move(dev, NULL) re-attach it to the virtual device
    > > > > tree instead of failing?
    > > >
    > > > Yes, that would be good to have.
    > >
    > > Cornelia, please fix this, because otherwise we can't detach a device
    > > from its parent. Storing the current virtual parent looks racy to me.
    >
    > You can always restore the previous "virtual" parent from the
    > information given to you in the device itself. That is what the code
    > does when it first registers the device.
    >
    > And yes, I too think it should be fixed.

    My knowledge of the driver model is still limited. Can you fix that
    quickly. This is really needed.

    Regards

    Marcel


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