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Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full()
From: |
Cornelia Huck |
Subject: |
Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full() |
Date: |
Tue, 8 Jan 2019 17:31:13 +0100 |
On Tue, 8 Jan 2019 11:08:56 -0500
Tony Krowiak <address@hidden> wrote:
> On 12/17/18 10:57 AM, Tony Krowiak wrote:
> > The qbus_is_full(BusState *bus) function (qdev_monitor.c) compares the
> > max_index
> > value of the BusState structure with the max_dev value of the BusClass
> > structure
> > to determine whether the maximum number of children has been reached for the
> > bus. The problem is, the max_index field of the BusState structure does not
> > necessarily reflect the number of devices that have been plugged into
> > the bus.
> >
> > Whenever a child device is plugged into the bus, the bus's max_index value
> > is
> > assigned to the child device and then incremented. If the child is
> > subsequently
> > unplugged, the value of the max_index does not change and no longer
> > reflects the
> > number of children.
> >
> > When the bus's max_index value reaches the maximum number of devices
> > allowed for the bus (i.e., the max_dev field in the BusClass structure),
> > attempts to plug another device will be rejected claiming that the bus is
> > full -- even if the bus is actually empty.
> >
> > To resolve the problem, a new 'num_children' field is being added to the
> > BusState structure to keep track of the number of children plugged into the
> > bus. It will be incremented when a child is plugged, and decremented when a
> > child is unplugged.
> >
> > Signed-off-by: Tony Krowiak <address@hidden>
> > Reviewed-by: Pierre Morel<address@hidden>
> > Reviewed-by: Halil Pasic <address@hidden>
> > ---
> > hw/core/qdev.c | 3 +++
> > include/hw/qdev-core.h | 1 +
> > qdev-monitor.c | 2 +-
> > 3 files changed, 5 insertions(+), 1 deletion(-)
>
> Ping ...
> I could not determine who the maintainer is for the three files
> listed above. I checked the MAINTAINERS file and the prologue of each
> individual file. Can someone please tell me who is responsible
> for merging these changes? Any additional review comments?
>
> >
> > diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> > index 6b3cc55b27c2..956923f33520 100644
> > --- a/hw/core/qdev.c
> > +++ b/hw/core/qdev.c
> > @@ -59,6 +59,8 @@ static void bus_remove_child(BusState *bus, DeviceState
> > *child)
> > snprintf(name, sizeof(name), "child[%d]", kid->index);
> > QTAILQ_REMOVE(&bus->children, kid, sibling);
> >
> > + bus->num_children--;
> > +
> > /* This gives back ownership of kid->child back to us. */
> > object_property_del(OBJECT(bus), name, NULL);
> > object_unref(OBJECT(kid->child));
> > @@ -73,6 +75,7 @@ static void bus_add_child(BusState *bus, DeviceState
> > *child)
> > char name[32];
> > BusChild *kid = g_malloc0(sizeof(*kid));
> >
> > + bus->num_children++;
> > kid->index = bus->max_index++;
Hm... I'm wondering what happens for insane numbers of hotplugging
operations here?
(Preexisting problem for busses without limit, but busses with a limit
could now run into that as well.)
> > kid->child = child;
> > object_ref(OBJECT(kid->child));
> > diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> > index a24d0dd566e3..521f0a947ead 100644
> > --- a/include/hw/qdev-core.h
> > +++ b/include/hw/qdev-core.h
> > @@ -206,6 +206,7 @@ struct BusState {
> > HotplugHandler *hotplug_handler;
> > int max_index;
> > bool realized;
> > + int num_children;
> > QTAILQ_HEAD(ChildrenHead, BusChild) children;
> > QLIST_ENTRY(BusState) sibling;
> > };
> > diff --git a/qdev-monitor.c b/qdev-monitor.c
> > index 07147c63bf8b..45a8ba49644c 100644
> > --- a/qdev-monitor.c
> > +++ b/qdev-monitor.c
> > @@ -414,7 +414,7 @@ static DeviceState *qbus_find_dev(BusState *bus, char
> > *elem)
> > static inline bool qbus_is_full(BusState *bus)
> > {
> > BusClass *bus_class = BUS_GET_CLASS(bus);
> > - return bus_class->max_dev && bus->max_index >= bus_class->max_dev;
> > + return bus_class->max_dev && bus->num_children >= bus_class->max_dev;
> > }
> >
> > /*
> >
The approach the patch takes looks sane to me.
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Tony Krowiak, 2019/01/08
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(),
Cornelia Huck <=
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Halil Pasic, 2019/01/08
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Cornelia Huck, 2019/01/08
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Tony Krowiak, 2019/01/08
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Cornelia Huck, 2019/01/09
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Tony Krowiak, 2019/01/09
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Halil Pasic, 2019/01/09
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Tony Krowiak, 2019/01/10
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Cornelia Huck, 2019/01/10
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Halil Pasic, 2019/01/11
- Re: [Qemu-devel] [PATCH v3] qdev/core: fix qbus_is_full(), Halil Pasic, 2019/01/11