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    SubjectRe: INFO: possible recursive locking detected ps2_command
    On Fri, Sep 04, 2009 at 12:48:45AM +0200, Zdenek Kabelac wrote:
    > 2008/8/8 Dmitry Torokhov <dmitry.torokhov@gmail.com>:
    > > On Fri, Aug 08, 2008 at 12:49:49PM +0200, Peter Zijlstra wrote:
    > >> On Thu, 2008-07-31 at 23:04 -0400, Dmitry Torokhov wrote:
    > >> > On Thu, Jul 31, 2008 at 02:57:39PM -0700, Andrew Morton wrote:
    > >> > >
    > >> > > (cc linux-input)
    > >> > >
    > >> > > On Thu, 31 Jul 2008 11:41:25 +0200
    > >> > > "Zdenek Kabelac" <zdenek.kabelac@gmail.com> wrote:
    > >> > >
    > >> > > > Hi
    > >> > > >
    > >> > > > During mouse unplugging from psaux connector from the laptops' docking
    > >> > > > station I've got attached INFO trace.
    > >> > > > (laptops still has synaptics device)
    > >> > > >
    > >> >
    > >> > Dell?
    > >> >
    > >> > > > Also for unknown reason to me  psaux mouse & synaptic device do not
    > >> > > > work somehow together - is it hw limitation
    > >> > > > of /dev/input/mice  interface?
    > >> > > > (USB mouse and synaptics do work quite well together)
    > >> > > >
    > >> > > > [ INFO: possible recursive locking detected ]
    > >> > > > 2.6.27-rc1 #48
    > >> > >
    > >> > > (it's 2.6.27-rc1)
    > >> > >
    > >> >
    > >> > Peter, here is the trace we talked about long time ago. For some reason
    > >> > lockdep annotation only works once. If reconnect is forced or psmouse
    > >> > module is reloaded lockdep starts complaining about passthrough port.
    > >>
    > >> Bit puzzling - and I don't have any ps2 hardware around to test with
    > >> (nor do I normally use modules - but that is fixable of course).
    > >>
    > >> Does Rabin's patch help?
    > >>
    > >>   http://lkml.org/lkml/2008/8/7/329
    > >>
    > >
    > > I doubt it resolves problem fully because it only takes care of module
    > > unload. I can easily trip lockdep by reconnecting the device. Just to
    > > give some more details about the problem:
    > >
    > >  - synaptics touchpads have a pass-through port that allows to connect
    > >   either external mouse or maybe a trackpoint device. Both devices
    > >   are represented by 'serio' structures and are handled by the same
    > >   driver (psmouse).
    > >
    > >  - as far as I know we have proper locking there and lockdep
    > >   annotatinos were added to lockdep to reflect the nesting of the
    > >   serio ports.
    > >
    > >  - if child port (pass-through port) is destroyed and recreated (due
    > >   to module unload, or because user requested reconnect through sysfs
    > >   or system-initiated reconnect) lockdep starts complaining although
    > >   the new child port should still have the same "depth" as the old
    > >   one.
    > >
    >
    > Well just noticed this issue again in my log - during resume operation
    > - thus no external mouse connection in the game this time:
    >

    External mouse does not have to be connected, the fact that you have
    a pass-through serio port is enough to trigger this warning.

    --
    Dmitry
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