Re: [BUG] object: is not initialized, yet kobject_put() is being called

[Alan Ott]

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@xxxxxxxx>
> > > > 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@xxxxxxxx>
> > > >      Cc: Jiri Kosina<jkosina@xxxxxxx>
> > > >      Cc: "Greg Kroah-Hartman"<gregkh@xxxxxxx>
> > > >      Signed-off-by: Jiri Kosina<jkosina@xxxxxxx>
> > > >          
> > > 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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