Re: [PATCH v7 02/11] hw/core/qdev: add trace events to help with resettable transition

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

On 1/15/20 1:36 PM, Damien Hedde wrote:
> Adds trace events to reset procedure and when updating the parent
> bus of a device.
> 
> Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
>   hw/core/qdev.c       | 29 ++++++++++++++++++++++++++---
>   hw/core/trace-events |  9 +++++++++
>   2 files changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 8c0c8284c8..5cb03136b5 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -38,6 +38,7 @@
>   #include "hw/boards.h"
>   #include "hw/sysbus.h"
>   #include "migration/vmstate.h"
> +#include "trace.h"
>   
>   bool qdev_hotplug = false;
>   static bool qdev_hot_added = false;
> @@ -98,7 +99,11 @@ void qdev_set_parent_bus(DeviceState *dev, BusState *bus)
>       bool replugging = dev->parent_bus != NULL;
>   
>       if (replugging) {
> -        /* Keep a reference to the device while it's not plugged into
> +        trace_qdev_update_parent_bus(dev, object_get_typename(OBJECT(dev)),
> +            dev->parent_bus, object_get_typename(OBJECT(dev->parent_bus)),
> +            OBJECT(bus), object_get_typename(OBJECT(bus)));
> +        /*
> +         * Keep a reference to the device while it's not plugged into
>            * any bus, to avoid it potentially evaporating when it is
>            * dereffed in bus_remove_child().
>            */
> @@ -296,6 +301,18 @@ HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
>       return hotplug_ctrl;
>   }
>   
> +static int qdev_prereset(DeviceState *dev, void *opaque)
> +{
> +    trace_qdev_reset_tree(dev, object_get_typename(OBJECT(dev)));
> +    return 0;
> +}
> +
> +static int qbus_prereset(BusState *bus, void *opaque)
> +{
> +    trace_qbus_reset_tree(bus, object_get_typename(OBJECT(bus)));
> +    return 0;
> +}
> +
>   static int qdev_reset_one(DeviceState *dev, void *opaque)
>   {
>       device_legacy_reset(dev);
> @@ -306,6 +323,7 @@ static int qdev_reset_one(DeviceState *dev, void *opaque)
>   static int qbus_reset_one(BusState *bus, void *opaque)
>   {
>       BusClass *bc = BUS_GET_CLASS(bus);
> +    trace_qbus_reset(bus, object_get_typename(OBJECT(bus)));
>       if (bc->reset) {
>           bc->reset(bus);
>       }
> @@ -314,7 +332,9 @@ static int qbus_reset_one(BusState *bus, void *opaque)
>   
>   void qdev_reset_all(DeviceState *dev)
>   {
> -    qdev_walk_children(dev, NULL, NULL, qdev_reset_one, qbus_reset_one, NULL);
> +    trace_qdev_reset_all(dev, object_get_typename(OBJECT(dev)));
> +    qdev_walk_children(dev, qdev_prereset, qbus_prereset,
> +                       qdev_reset_one, qbus_reset_one, NULL);
>   }
>   
>   void qdev_reset_all_fn(void *opaque)
> @@ -324,7 +344,9 @@ void qdev_reset_all_fn(void *opaque)
>   
>   void qbus_reset_all(BusState *bus)
>   {
> -    qbus_walk_children(bus, NULL, NULL, qdev_reset_one, qbus_reset_one, NULL);
> +    trace_qbus_reset_all(bus, object_get_typename(OBJECT(bus)));
> +    qbus_walk_children(bus, qdev_prereset, qbus_prereset,
> +                       qdev_reset_one, qbus_reset_one, NULL);
>   }
>   
>   void qbus_reset_all_fn(void *opaque)
> @@ -1131,6 +1153,7 @@ void device_legacy_reset(DeviceState *dev)
>   {
>       DeviceClass *klass = DEVICE_GET_CLASS(dev);
>   
> +    trace_qdev_reset(dev, object_get_typename(OBJECT(dev)));
>       if (klass->reset) {
>           klass->reset(dev);
>       }
> diff --git a/hw/core/trace-events b/hw/core/trace-events
> index fe47a9c8cb..a375aa88a4 100644
> --- a/hw/core/trace-events
> +++ b/hw/core/trace-events
> @@ -1,2 +1,11 @@
>   # loader.c
>   loader_write_rom(const char *name, uint64_t gpa, uint64_t size, bool isrom) "%s: @0x%"PRIx64" size=0x%"PRIx64" ROM=%d"
> +
> +# qdev.c
> +qdev_reset(void *obj, const char *objtype) "obj=%p(%s)"
> +qdev_reset_all(void *obj, const char *objtype) "obj=%p(%s)"
> +qdev_reset_tree(void *obj, const char *objtype) "obj=%p(%s)"
> +qbus_reset(void *obj, const char *objtype) "obj=%p(%s)"
> +qbus_reset_all(void *obj, const char *objtype) "obj=%p(%s)"
> +qbus_reset_tree(void *obj, const char *objtype) "obj=%p(%s)"
> +qdev_update_parent_bus(void *obj, const char *objtype, void *oldp, const char *oldptype, void *newp, const char *newptype) "obj=%p(%s) old_parent=%p(%s) new_parent=%p(%s)"
>