On Thu, Aug 12, 2010 at 02:57:57PM +0200, Jiri Kosina wrote:

On Thu, 12 Aug 2010, Jiri Kosina wrote:

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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 [off-list ref]
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 [off-list ref]
    Cc: Jiri Kosina [off-list ref]
    Cc: "Greg Kroah-Hartman" [off-list ref]
    Signed-off-by: Jiri Kosina [off-list ref]

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

Could please those of you, who are able to reproduce the problem, verify 
whether the patch below (completely untested) makes everything behave 
again? Thanks.

Yes, everything behaves again. Thanks Jiri.

-- 
»A man who doesn't know he is in prison can never escape.«
William S. Burroughs