Re: [PATCH v2 1/2] s390x: fix memleaks in cpu_finalize

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 17 Feb 2020 11:21:26 +0800
<pannengyuan@huawei.com> wrote:

> From: Pan Nengyuan <pannengyuan@huawei.com>
> 
> 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: Cornelia Huck <cohuck@redhat.com>
> ---
> Changes v2 to v1:
> - Similarly to other cleanups, move timer_new into realize, then do
> timer_del in unrealize.
> ---
>  target/s390x/cpu.c | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
> index cf84d307c6..f18dbc6fe4 100644
> --- a/target/s390x/cpu.c
> +++ b/target/s390x/cpu.c
> @@ -170,7 +170,12 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp)
>      S390CPUClass *scc = S390_CPU_GET_CLASS(dev);
>  #if !defined(CONFIG_USER_ONLY)
>      S390CPU *cpu = S390_CPU(dev);
> +    cpu->env.tod_timer =
> +        timer_new_ns(QEMU_CLOCK_VIRTUAL, s390x_tod_timer, cpu);
> +    cpu->env.cpu_timer =
> +        timer_new_ns(QEMU_CLOCK_VIRTUAL, s390x_cpu_timer, cpu);

I may be missing something, but what cleans up the timers if we fail
further down in this function? I don't think the unrealize callback is
invoked by the core in case of error?

Also, as a matter of personal preference, I think it would be better to
initialize the timers in the !CONFIG_USER_ONLY section further below,
rather than in the variable declaration section.

>  #endif
> +
>      Error *err = NULL;
>  
>      /* the model has to be realized before qemu_init_vcpu() due to kvm */