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

    Hi,

    On Monday 21 December 2009 11:46:32 pm Dmitry Torokhov wrote:
    > 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.

    I don't see it fixed in Linus' tree or linux-next yet so here is a patch:
    (thanks for noticing the issue and sorry for the delayed reply).

    [ Jonathan, please apply. Thanks! ]

    From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
    Subject: [PATCH] fujitsu-laptop: fix input_free_device() usage

    input_free_device() must not be used after calling input_unregister_device()
    since unregister likely drops the last reference to the device and it will
    get freed by input core.

    Fix all input_unregister_device()+input_free_device() occurences accordingly.

    Noticed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
    Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
    ---
    against current Linus' tree

    drivers/platform/x86/fujitsu-laptop.c | 6 ++----
    1 file changed, 2 insertions(+), 4 deletions(-)

    Index: b/drivers/platform/x86/fujitsu-laptop.c
    ===================================================================
    --- a/drivers/platform/x86/fujitsu-laptop.c
    +++ b/drivers/platform/x86/fujitsu-laptop.c
    @@ -724,6 +724,7 @@ static int acpi_fujitsu_add(struct acpi_

    err_unregister_input_dev:
    input_unregister_device(input);
    + input = NULL;
    err_free_input_dev:
    input_free_device(input);
    err_stop:
    @@ -737,8 +738,6 @@ static int acpi_fujitsu_remove(struct ac

    input_unregister_device(input);

    - input_free_device(input);
    -
    fujitsu->acpi_handle = NULL;

    return 0;
    @@ -929,6 +928,7 @@ static int acpi_fujitsu_hotkey_add(struc

    err_unregister_input_dev:
    input_unregister_device(input);
    + input = NULL;
    err_free_input_dev:
    input_free_device(input);
    err_free_fifo:
    @@ -952,8 +952,6 @@ static int acpi_fujitsu_hotkey_remove(st

    input_unregister_device(input);

    - input_free_device(input);
    -
    kfifo_free(&fujitsu_hotkey->fifo);

    fujitsu_hotkey->acpi_handle = NULL;


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