Re: [PATCH v5 02/13] hw/core/qdev: add trace events to help with resettable transition

[Philippe Mathieu-Daudé]

On 11/4/19 1:16 PM, Damien Hedde wrote:
> On 11/1/19 12:23 AM, Philippe Mathieu-Daudé wrote:
> > On 10/18/19 5:06 PM, Damien Hedde wrote:
> > > Adds trace events to reset procedure and when updating the parent
> > > bus of a device.
> > >
> > > Signed-off-by: Damien Hedde <address@hidden>
> > > ---
> > >    hw/core/qdev.c       | 27 ++++++++++++++++++++++++---
> > >    hw/core/trace-events |  9 +++++++++
> > >    2 files changed, 33 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> > > index 60be2f2fef..f230063189 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 +99,9 @@ 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, dev->parent_bus, bus);
> >
> > Nitpicking, if you respin, can you add object_get_typename(OBJECT(dev)))
> > and object_get_typename(OBJECT(bus)))?
>
> sure. I was wondering if having some kind of qom object support to trace
> would be feasible. Because it's a bit tedious to add this each time. And
> IMO it would be more useful to have the path, but we can't reasonably
> compute it as a trace_..() arguments.

Meanwhile you can use:

  if (trace_event_get_state_backends(TRACE_QDEV_UPDATE_PARENT_BUS)) {
      ...

> > With/without it:
> > Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> >
> > > +        /*
> > > +         * 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().
> > >             */
> > > @@ -272,6 +275,18 @@ 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);
> > > @@ -282,6 +297,7 @@ 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);
> > >        }
> > > @@ -290,7 +306,9 @@ 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)
> > > @@ -300,7 +318,9 @@ 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)
> > > @@ -1108,6 +1128,7 @@ 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..1a669be0ea 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, void *oldp, void *newp) "obj=%p
> > > old_parent=%p new_parent=%p"