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    SubjectRe: [PATCH] fujitsu-laptop: driver [un]registration fixes
    Date
    Hi Jonathan,

    On Monday 21 December 2009 02:32:40 pm Jonathan Woithe wrote:
    > Hi Dmitry
    >
    > > On Wed, Jul 29, 2009 at 10:15:33PM +0200, Bartlomiej Zolnierkiewicz wrote:
    > > > @@ -722,22 +722,22 @@ static int acpi_fujitsu_add(struct acpi_
    > > >
    > > > return result;
    > > >
    > > > -end:
    > > > +err_unregister_input_dev:
    > > > + input_unregister_device(input);
    > > > err_free_input_dev:
    > > > input_free_device(input);
    > > > err_stop:
    > >
    > > Just noticed it scanning ACPI list. You must not use input_free_device()
    > > after calling input_unregister_device() since unregister likely drops the
    > > last reference to the device and it will get freed by input core.
    >
    > So what's the correct way to deal with that in this case? Something like
    >
    > -end:
    > +err_unregister_input_dev:
    > + input_unregister_device(input);
    > + goto err_stop;
    > err_free_input_dev:
    > input_free_device(input);
    > err_stop:
    >
    > (with a short comment to explain the goto) would circumvent the problem but
    > it looks ugly (at least to my eyes - I've never really liked "goto"s :-) ).

    Just do "input = NULL;" after calling input_unregister_device() -
    input_free_device() is like kfree() and will happily ignore passed NULL
    pointers.

    Or rearrange the code to register device last, when everything is ready.

    >
    > > For polled input devices you need to use both unregister and free though
    > > because polled device structure is not refcounted (but underlying input
    > > device is).
    >
    > This isn't a polled input device AFAIK so this doesn't apply here, right?

    Right, it was more of a general statement so I don't get bunch of patches
    removing input_free_polled_device() after calls to
    input_unregister_polled_device() ;)

    --
    Dmitry


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