Re: [Qemu-devel] [PATCH for-4.1? 1/2] stellaris_input: Fix vmstate description of buttons field

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Maydell (peter.maydell@linaro.org) wrote:
> gamepad_state::buttons is a pointer to an array of structs,
> not an array of structs, so should be declared in the vmstate
> with VMSTATE_STRUCT_VARRAY_POINTER_INT32; otherwise we
> corrupt memory on incoming migration.
> 
> We bump the vmstate version field as the easiest way to
> deal with the migration break, since migration wouldn't have
> worked reliably before anyway.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

OK, it would be great to change num_buttons to uint32_t and make that a
UINT32 at some point;  it's hard to press negative buttons.


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  hw/input/stellaris_input.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/input/stellaris_input.c b/hw/input/stellaris_input.c
> index 20c87d86f40..3a666d61d47 100644
> --- a/hw/input/stellaris_input.c
> +++ b/hw/input/stellaris_input.c
> @@ -60,12 +60,14 @@ static const VMStateDescription vmstate_stellaris_button = {
>  
>  static const VMStateDescription vmstate_stellaris_gamepad = {
>      .name = "stellaris_gamepad",
> -    .version_id = 1,
> -    .minimum_version_id = 1,
> +    .version_id = 2,
> +    .minimum_version_id = 2,
>      .fields = (VMStateField[]) {
>          VMSTATE_INT32(extension, gamepad_state),
> -        VMSTATE_STRUCT_VARRAY_INT32(buttons, gamepad_state, num_buttons, 0,
> -                              vmstate_stellaris_button, gamepad_button),
> +        VMSTATE_STRUCT_VARRAY_POINTER_INT32(buttons, gamepad_state,
> +                                            num_buttons,
> +                                            vmstate_stellaris_button,
> +                                            gamepad_button),
>          VMSTATE_END_OF_LIST()
>      }
>  };
> -- 
> 2.20.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK