Re: [PATCH v2 5/6] hw/input/stellaris_input: Convert to qdev

[Peter Maydell]

On Mon, 30 Oct 2023 at 13:52, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> Hi Peter,
>
> Cc'ing Markus for QObject.
>
> On 30/10/23 12:48, Peter Maydell wrote:
> > Convert the hw/input/stellaris_input device to qdev.
> >
> > The interface uses an array property for the board to specify the
> > keycodes to use, so the s->keycodes memory is now allocated by the
> > array-property machinery.
> >
> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > ---
> > v1->v2: drop private/public comment lines
> > ---
> >   include/hw/input/stellaris_gamepad.h | 22 ++++++++-
> >   hw/arm/stellaris.c                   | 26 +++++++---
> >   hw/input/stellaris_gamepad.c         | 73 +++++++++++++++++++---------
> >   3 files changed, 89 insertions(+), 32 deletions(-)
>
>
> > diff --git a/hw/arm/stellaris.c b/hw/arm/stellaris.c
> > index 96585dd7106..707b0dae375 100644
> > --- a/hw/arm/stellaris.c
> > +++ b/hw/arm/stellaris.c
> > @@ -31,6 +31,7 @@
> >   #include "hw/timer/stellaris-gptm.h"
> >   #include "hw/qdev-clock.h"
> >   #include "qom/object.h"
> > +#include "qapi/qmp/qlist.h"
> >
> >   #define GPIO_A 0
> >   #define GPIO_B 1
> > @@ -1274,16 +1275,27 @@ static void stellaris_init(MachineState *ms, 
> > stellaris_board_info *board)
> >           sysbus_connect_irq(SYS_BUS_DEVICE(enet), 0, 
> > qdev_get_gpio_in(nvic, 42));
> >       }
> >       if (board->peripherals & BP_GAMEPAD) {
> > -        qemu_irq gpad_irq[5];
> > +        QList *gpad_keycode_list = qlist_new();
>
> I'm trying to understand better qlist_new(), but unfortunately there
> is not much documentation. Looking at how the allocated list was
> released, I found use of g_autoptr in tests/unit/check-qobject.c,
> so I tried:
>
>             g_autoptr(QList) gpad_keycode_list = qlist_new();

The API for qdev_prop_set_array() documents that it takes ownership
of the list you pass it (and it ends up calling qobject_unref() on it).
So I think adding g_autoptr() here will result in the memory being
double-freed (once inside qobject_unref() when the refcount
goes to 0, and once when g_autoptr frees it as it goes out of scope)...

> * thread #2, stop reason = signal SIGABRT
>    * frame #0: 0x8b1eb11c libsystem_kernel.dylib`__pthread_kill + 8
>      frame #1: 0x8b222cc0 libsystem_pthread.dylib`pthread_kill + 288
>      frame #2: 0x8b132a50 libsystem_c.dylib`abort + 180
>      frame #3: 0x8b049b08 libsystem_malloc.dylib`malloc_vreport + 908
>      frame #4: 0x8b06924c libsystem_malloc.dylib`malloc_zone_error + 104
>      frame #5: 0x8b05b094
> libsystem_malloc.dylib`nanov2_guard_corruption_detected + 44
>      frame #6: 0x8b05a2a8
> libsystem_malloc.dylib`nanov2_allocate_outlined + 404
>      frame #7: 0x0201fdc0 libglib-2.0.0.dylib`g_malloc0 + 36
>      frame #8: 0x02007718 libglib-2.0.0.dylib`g_hash_table_setup_storage
> + 76
>      frame #9: 0x020076b0 libglib-2.0.0.dylib`g_hash_table_new_full + 96

...which is probably why a later memory operation runs into a
malloc data corruption assertion.

thanks
-- PMM