Re: [PATCH] pl031: add finalize function to avoid memleaks

[Peter Maydell]

On Mon, 3 Feb 2020 at 07:47, <address@hidden> wrote:
>
> From: Pan Nengyuan <address@hidden>
>
> There is a memory leak when we call 'device_list_properties' with
> typename = pl031. It's easy to reproduce as follow:
>
>   virsh qemu-monitor-command vm1 --pretty '{"execute": 
> "device-list-properties", "arguments": {"typename": "pl031"}}'
>
> The memory leak stack:
>   Direct leak of 48 byte(s) in 1 object(s) allocated from:
>     #0 0x7f6e0925a970 in __interceptor_calloc (/lib64/libasan.so.5+0xef970)
>     #1 0x7f6e06f4d49d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5249d)
>     #2 0x564a0f7654ea in timer_new_full /mnt/sdb/qemu/include/qemu/timer.h:530
>     #3 0x564a0f76555d in timer_new /mnt/sdb/qemu/include/qemu/timer.h:551
>     #4 0x564a0f765589 in timer_new_ns /mnt/sdb/qemu/include/qemu/timer.h:569
>     #5 0x564a0f76747d in pl031_init /mnt/sdb/qemu/hw/rtc/pl031.c:198
>     #6 0x564a0fd4a19d in object_init_with_type /mnt/sdb/qemu/qom/object.c:360
>     #7 0x564a0fd4b166 in object_initialize_with_type 
> /mnt/sdb/qemu/qom/object.c:467
>     #8 0x564a0fd4c8e6 in object_new_with_type /mnt/sdb/qemu/qom/object.c:636
>     #9 0x564a0fd4c98e in object_new /mnt/sdb/qemu/qom/object.c:646
>     #10 0x564a0fc69d43 in qmp_device_list_properties 
> /mnt/sdb/qemu/qom/qom-qmp-cmds.c:204
>     #11 0x564a0ef18e64 in qdev_device_help /mnt/sdb/qemu/qdev-monitor.c:278
>
> Reported-by: Euler Robot <address@hidden>
> Signed-off-by: Pan Nengyuan <address@hidden>
> ---
>  hw/rtc/pl031.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/hw/rtc/pl031.c b/hw/rtc/pl031.c
> index ae47f09635..50664ca000 100644
> --- a/hw/rtc/pl031.c
> +++ b/hw/rtc/pl031.c
> @@ -194,6 +194,15 @@ static void pl031_init(Object *obj)
>      s->timer = timer_new_ns(rtc_clock, pl031_interrupt, s);
>  }
>
> +static void pl031_finalize(Object *obj)
> +{
> +    PL031State *s = PL031(obj);
> +    if (s->timer) {
> +        timer_del(s->timer);
> +        timer_free(s->timer);
> +    }
> +}
> +
>  static int pl031_pre_save(void *opaque)
>  {
>      PL031State *s = opaque;
> @@ -329,6 +338,7 @@ static const TypeInfo pl031_info = {
>      .parent        = TYPE_SYS_BUS_DEVICE,
>      .instance_size = sizeof(PL031State),
>      .instance_init = pl031_init,
> +    .instance_finalize = pl031_finalize,
>      .class_init    = pl031_class_init,
>  };

The more usual way to fix this I think is to delay
the timer_new until realize rather than putting it
into instance_init, since the pl031 can't be
hotplugged.

thanks
-- PMM