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    SubjectRe: [BUG] object: is not initialized, yet kobject_put() is being called
    On Thu, 12 Aug 2010, Markus Trippelsdorf wrote:

    > > > > > > Guys, could you please send me your .config with which you are
    > > > > > > experiencing the problem, so that I can try to reproduce it with it?
    > > > > >
    > > > > > Attached.
    > > > >
    > > > > So I had to add support for HW of mine (SATA_VIA, PATA_VIA, disabled the
    > > > > radeon firmware stuff, and, most importantly, enabled UHCI, which is what
    > > > > is on machine I am using now for testing), and disconnect-connect cycle
    > > > > works nicely:
    > > > >
    > > > > usb 3-2: USB disconnect, address 3
    > > > > usb 3-2: new low speed USB device using uhci_hcd and address 4
    > > > > input: mouse USB mouse with wheel as /devices/pci0000:00/0000:00:10.1/usb3/3-2/3-2:1.0/input/input6
    > > > > generic-usb 0003:05B8:3091.0004: input,hidraw0: USB HID v1.10 Mouse [mouse USB mouse with wheel] on usb-0000:00:10.1-2/input0
    > > > > input: mouse USB mouse with wheel as /devices/pci0000:00/0000:00:10.1/usb3/3-2/3-2:1.1/input/input7
    > > > > generic-usb 0003:05B8:3091.0005: input,hidraw1: USB HID v1.10 Keyboard [mouse USB mouse with wheel] on usb-0000:00:10.1-2/input1
    > > > >
    > > > > so still no BUG from kobject refcounting, and the hidraw numbers are the
    > > > > same. The major difference seems to be that I am using UHCI and you have
    > > > > your HID devices connected through OHCI, is that correct?
    > > >
    > > > Correct. And I should add that it very easy to reproduce here; just
    > > > disconnecting the usb receiver triggers the WARNING.
    > >
    > > Disabling USB_HIDDEV in my .config solves the problem (there is no
    > > WARNING anymore when disconnecting the receiver).
    >
    > Reverting bd25f4dd6972755579d0ea50d1a5ace2e9b00d1a with USB_HIDDEV
    > enabled also solves the problem. So there must be a bug in that patch:
    >
    > commit bd25f4dd6972755579d0ea50d1a5ace2e9b00d1a
    > Author: Arnd Bergmann <arnd@arndb.de>
    > Date: Sun Jul 11 15:34:05 2010 +0200
    >
    > HID: hiddev: use usb_find_interface, get rid of BKL
    >
    > This removes the private hiddev_table in the usbhid
    > driver and changes it to use usb_find_interface
    > instead.
    >
    > The advantage is that we can avoid the race between
    > usb_register_dev and usb_open and no longer need the
    > big kernel lock.
    >
    > This doesn't introduce race condition -- the intf pointer could be
    > invalidated only in hiddev_disconnect() through usb_deregister_dev(),
    > but that will block on minor_rwsem and not actually remove the device
    > until usb_open().
    >
    > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    > Cc: Jiri Kosina <jkosina@suse.cz>
    > Cc: "Greg Kroah-Hartman" <gregkh@suse.de>
    > Signed-off-by: Jiri Kosina <jkosina@suse.cz>

    Thanks, I had my suspicion about this commit (that's why I asked to you
    verify with CONFIG_USB_HIDDEV turned off as well).

    Adding Arnd to CC and will look into it myself as well soon.

    Arnd, the complete thread can be found at
    http://lkml.org/lkml/2010/8/10/280

    --
    Jiri Kosina
    SUSE Labs, Novell Inc.


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