Re: [Qemu-devel] [PATCH 4/5] qom: delay DeviceState's reclaim to main-loop

[Stefan Hajnoczi]

On Wed, Jul 25, 2012 at 4:31 AM, Liu Ping Fan <address@hidden> wrote:
> From: Liu Ping Fan <address@hidden>
>
> iohandler/bh/timer may use DeviceState when its refcnt=0,
> postpone the reclaimer till they have done with it.
>
> Signed-off-by: Liu Ping Fan <address@hidden>
> ---
>  include/qemu/object.h |    2 +-
>  main-loop.c           |    4 ++++
>  main-loop.h           |    2 ++
>  qemu-tool.c           |    4 ++++
>  qom/Makefile.objs     |    2 +-
>  qom/object.c          |    7 ++++++-
>  qom/reclaimer.c       |   41 +++++++++++++++++++++++++++++++++++++++++
>  7 files changed, 59 insertions(+), 3 deletions(-)
>  create mode 100644 qom/reclaimer.c
>
> diff --git a/include/qemu/object.h b/include/qemu/object.h
> index 8b17776..b233ee4 100644
> --- a/include/qemu/object.h
> +++ b/include/qemu/object.h
> @@ -958,5 +958,5 @@ int object_child_foreach(Object *obj, int (*fn)(Object 
> *child, void *opaque),
>   */
>  Object *container_get(Object *root, const char *path);
>
> -
> +void qemu_reclaimer_enqueue(Object *obj);
>  #endif
> diff --git a/main-loop.c b/main-loop.c
> index eb3b6e6..f9cecc5 100644
> --- a/main-loop.c
> +++ b/main-loop.c
> @@ -505,5 +505,9 @@ int main_loop_wait(int nonblocking)
>         them.  */
>      qemu_bh_poll();
>
> +    /* ref to device from iohandler/bh/timer do not obey the rules, so delay
> +     * reclaiming until now.
> +     */
> +    qemu_device_reclaimer();
>      return ret;
>  }
> diff --git a/main-loop.h b/main-loop.h
> index cedddf5..1a59a6d 100644
> --- a/main-loop.h
> +++ b/main-loop.h
> @@ -367,4 +367,6 @@ void qemu_bh_schedule_idle(QEMUBH *bh);
>  int qemu_bh_poll(void);
>  void qemu_bh_update_timeout(uint32_t *timeout);
>
> +void qemu_device_reclaimer(void);
> +
>  #endif
> diff --git a/qemu-tool.c b/qemu-tool.c
> index 318c5fc..34d959b 100644
> --- a/qemu-tool.c
> +++ b/qemu-tool.c
> @@ -75,6 +75,10 @@ void qemu_mutex_unlock_iothread(void)
>  {
>  }
>
> +void qemu_device_reclaimer(void)
> +{
> +}
> +
>  int use_icount;
>
>  void qemu_clock_warp(QEMUClock *clock)
> diff --git a/qom/Makefile.objs b/qom/Makefile.objs
> index 5ef060a..a579261 100644
> --- a/qom/Makefile.objs
> +++ b/qom/Makefile.objs
> @@ -1,4 +1,4 @@
> -qom-obj-y = object.o container.o qom-qobject.o
> +qom-obj-y = object.o container.o qom-qobject.o reclaimer.o
>  qom-obj-twice-y = cpu.o
>  common-obj-y = $(qom-obj-twice-y)
>  user-obj-y = $(qom-obj-twice-y)
> diff --git a/qom/object.c b/qom/object.c
> index 00bb3b0..227d966 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -649,7 +649,12 @@ void object_unref(Object *obj)
>
>      /* parent always holds a reference to its children */
>      if (obj->ref == 0) {
> -        object_finalize(obj);
> +        /* fixme, maybe introduce obj->finalze to make this more elegant */
> +        if (object_dynamic_cast(obj, "TYPE_DEVICE") != NULL) {

hw/qdev.h:#define TYPE_DEVICE "device"

This should be object_dynamic_cast(obj, TYPE_DEVICE).

Stefan