linux-kernel - Re: [BUG] object: is not initialized, yet kobject

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Date:	Thu, 12 Aug 2010 09:09:25 -0400
From:	Alan Ott <alan@...nal11.us>
To:	Markus Trippelsdorf <markus@...ppelsdorf.de>
Cc:	Jiri Kosina <jkosina@...e.cz>, Heinz Diehl <htd@...tha.org>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-input@...r.kernel.org, Arnd Bergmann <arnd@...db.de>
Subject: Re: [BUG] object: is not initialized, yet kobject_put() is being   called

On 08/12/2010 09:04 AM, Markus Trippelsdorf wrote:
> On Thu, Aug 12, 2010 at 02:57:57PM +0200, Jiri Kosina wrote:
>    
>> On Thu, 12 Aug 2010, Jiri Kosina 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@...db.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@...db.de>
>>>>      Cc: Jiri Kosina<jkosina@...e.cz>
>>>>      Cc: "Greg Kroah-Hartman"<gregkh@...e.de>
>>>>      Signed-off-by: Jiri Kosina<jkosina@...e.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
>>>        
>> 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.
>    

Seconded. Works good. Thanks for your support Jiri.



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