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Re: [Qemu-devel] [PATCHv2] qdev: DEVICE_DELETED event
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCHv2] qdev: DEVICE_DELETED event |
Date: |
Wed, 6 Mar 2013 18:55:21 +0200 |
On Wed, Mar 06, 2013 at 05:52:05PM +0100, Paolo Bonzini wrote:
> Il 06/03/2013 17:49, Michael S. Tsirkin ha scritto:
> > libvirt has a long-standing bug: when removing the device,
> > it can request removal but does not know when the
> > removal completes. Add an event so we can fix this in a robust way.
> >
> > Signed-off-by: Michael S. Tsirkin <address@hidden>
> > ---
> >
> > Changes from v1:
> > - move to device_unparent
> > - address comments by Andreas and Eric
> >
> > Andreas also suggested a more generic object-deleted event,
> > I'm not sure how useful that is so let's add what we already need, for
> > devices with an id and wait and see what's necessary for non-device
> > objects?
> >
> > QMP/qmp-events.txt | 15 +++++++++++++++
> > hw/qdev.c | 7 +++++++
> > include/monitor/monitor.h | 1 +
> > monitor.c | 1 +
> > qapi-schema.json | 4 +++-
> > 5 files changed, 27 insertions(+), 1 deletion(-)
> >
> > diff --git a/QMP/qmp-events.txt b/QMP/qmp-events.txt
> > index b2698e4..f2f115a 100644
> > --- a/QMP/qmp-events.txt
> > +++ b/QMP/qmp-events.txt
> > @@ -136,6 +136,21 @@ Example:
> > Note: The "ready to complete" status is always reset by a BLOCK_JOB_ERROR
> > event.
> >
> > +DEVICE_DELETED
> > +-----------------
> > +
> > +Emitted whenever the device removal completion is acknowledged
> > +by the guest. At this point, it's safe to reuse the specified device ID.
> > +Device removal can be initiated by the guest or by HMP/QMP commands.
> > +
> > +Data:
> > +
> > +- "device": device name (json-string)
> > +
> > +{ "event": "DEVICE_DELETED",
> > + "data": { "device": "virtio-net-pci-0" },
> > + "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }
> > +
> > DEVICE_TRAY_MOVED
> > -----------------
> >
> > diff --git a/hw/qdev.c b/hw/qdev.c
> > index 689cd54..d603f4f 100644
> > --- a/hw/qdev.c
> > +++ b/hw/qdev.c
> > @@ -29,6 +29,7 @@
> > #include "sysemu/sysemu.h"
> > #include "qapi/error.h"
> > #include "qapi/visitor.h"
> > +#include "qapi/qmp/qjson.h"
> >
> > int qdev_hotplug = 0;
> > static bool qdev_hot_added = false;
> > @@ -761,6 +762,12 @@ static void device_unparent(Object *obj)
> > DeviceClass *dc = DEVICE_GET_CLASS(dev);
> > BusState *bus;
> >
> > + if (dev->id) {
> > + QObject *data = qobject_from_jsonf("{ 'device': %s }", dev->id);
> > + monitor_protocol_event(QEVENT_DEVICE_DELETED, data);
> > + qobject_decref(data);
> > + }
>
> Do this at the end of device_unparent, so that parents are reported
> after their children.
>
> Paolo
Hmm yes it seems cleaner, though we'd need to copy the
id as the device can go away.
Doing this after
while (dev->num_child_bus) {
bus = QLIST_FIRST(&dev->child_bus);
qbus_free(bus);
}
would be enough, isn't it?
> > while (dev->num_child_bus) {
> > bus = QLIST_FIRST(&dev->child_bus);
> > qbus_free(bus);
> > diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h
> > index 87fb49c..b868760 100644
> > --- a/include/monitor/monitor.h
> > +++ b/include/monitor/monitor.h
> > @@ -39,6 +39,7 @@ typedef enum MonitorEvent {
> > QEVENT_BLOCK_JOB_CANCELLED,
> > QEVENT_BLOCK_JOB_ERROR,
> > QEVENT_BLOCK_JOB_READY,
> > + QEVENT_DEVICE_DELETED,
> > QEVENT_DEVICE_TRAY_MOVED,
> > QEVENT_SUSPEND,
> > QEVENT_SUSPEND_DISK,
> > diff --git a/monitor.c b/monitor.c
> > index 32a6e74..2a5e7b6 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -457,6 +457,7 @@ static const char *monitor_event_names[] = {
> > [QEVENT_BLOCK_JOB_CANCELLED] = "BLOCK_JOB_CANCELLED",
> > [QEVENT_BLOCK_JOB_ERROR] = "BLOCK_JOB_ERROR",
> > [QEVENT_BLOCK_JOB_READY] = "BLOCK_JOB_READY",
> > + [QEVENT_DEVICE_DELETED] = "DEVICE_DELETED",
> > [QEVENT_DEVICE_TRAY_MOVED] = "DEVICE_TRAY_MOVED",
> > [QEVENT_SUSPEND] = "SUSPEND",
> > [QEVENT_SUSPEND_DISK] = "SUSPEND_DISK",
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 28b070f..bb361e1 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -2354,7 +2354,9 @@
> > # Notes: When this command completes, the device may not be removed from
> > the
> > # guest. Hot removal is an operation that requires guest
> > cooperation.
> > # This command merely requests that the guest begin the hot removal
> > -# process.
> > +# process. Completion of the device removal process is signaled
> > with a
> > +# DEVICE_DELETED event. Guest reset will automatically complete
> > removal
> > +# for all devices.
> > #
> > # Since: 0.14.0
> > ##
> >