Re: [PATCH v3 1/6] s390x: fix memleaks in cpu_finalize

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 2/27/20 9:41 AM, David Hildenbrand wrote:
> On 27.02.20 03:50, Pan Nengyuan wrote:
>> This patch fix memleaks when we call tests/qtest/cpu-plug-test on s390x. The leak stack is as follow:
>>
>> Direct leak of 48 byte(s) in 1 object(s) allocated from:
>>      #0 0x7fb43c7cd970 in __interceptor_calloc (/lib64/libasan.so.5+0xef970)
>>      #1 0x7fb43be2149d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5249d)
>>      #2 0x558ba96da716 in timer_new_full /mnt/sdb/qemu-new/qemu/include/qemu/timer.h:530
>>      #3 0x558ba96da716 in timer_new /mnt/sdb/qemu-new/qemu/include/qemu/timer.h:551
>>      #4 0x558ba96da716 in timer_new_ns /mnt/sdb/qemu-new/qemu/include/qemu/timer.h:569
>>      #5 0x558ba96da716 in s390_cpu_initfn /mnt/sdb/qemu-new/qemu/target/s390x/cpu.c:285
>>      #6 0x558ba9c969ab in object_init_with_type /mnt/sdb/qemu-new/qemu/qom/object.c:372
>>      #7 0x558ba9c9eb5f in object_initialize_with_type /mnt/sdb/qemu-new/qemu/qom/object.c:516
>>      #8 0x558ba9c9f053 in object_new_with_type /mnt/sdb/qemu-new/qemu/qom/object.c:684
>>      #9 0x558ba967ede6 in s390x_new_cpu /mnt/sdb/qemu-new/qemu/hw/s390x/s390-virtio-ccw.c:64
>>      #10 0x558ba99764b3 in hmp_cpu_add /mnt/sdb/qemu-new/qemu/hw/core/machine-hmp-cmds.c:57
>>      #11 0x558ba9b1c27f in handle_hmp_command /mnt/sdb/qemu-new/qemu/monitor/hmp.c:1082
>>      #12 0x558ba96c1b02 in qmp_human_monitor_command /mnt/sdb/qemu-new/qemu/monitor/misc.c:142
>>
>> Reported-by: Euler Robot <euler.robot@huawei.com>
>> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
>> ---
>> Cc: Richard Henderson <rth@twiddle.net>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Cornelia Huck <cohuck@redhat.com>
>> Cc: qemu-s390x@nongnu.org
>> ---
>> v2->v1:
>> - Similarly to other cleanups, move timer_new into realize(Suggested by Philippe Mathieu-Daudé)
>> v3->v2:
>> - Also do the timer_free in unrealize, it seems more balance.
>> ---
> 
> 
> As I already said, I think this is init and not realize stuff. Do we
> have a convention now and documented that?

The clearer doc I read so far is this post:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg680187.html
(but see the thread for more helpful comments)

Another thread that you might find interesting is "how to handle QOM 
'container' objects whose contents depend on QOM properties?"
https://www.mail-archive.com/qemu-devel@nongnu.org/msg511703.html

> 
> Anyhow, I don't really care
> [...]

Well, looking at the time spent on these series and their review, having 
it better documented might save time the whole community.

> 
>> @@ -453,6 +466,7 @@ static void s390_cpu_class_init(ObjectClass *oc, void *data)
>>   
>>       device_class_set_parent_realize(dc, s390_cpu_realizefn,
>>                                       &scc->parent_realize);
>> +    dc->unrealize = s390_cpu_unrealizefn;
> 
> Shouldn't we use device_class_set_parent_unrealize?
> 
>