* Re: [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device
2018-12-13 16:26 [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device Tony Krowiak
@ 2018-12-14 9:16 ` Pierre Morel
2018-12-14 14:35 ` Tony Krowiak
2018-12-14 9:22 ` Pierre Morel
2018-12-14 12:09 ` Halil Pasic
2 siblings, 1 reply; 6+ messages in thread
From: Pierre Morel @ 2018-12-14 9:16 UTC (permalink / raw)
To: Tony Krowiak, qemu-devel; +Cc: pasic, mammedo
On 13/12/2018 17:26, Tony Krowiak wrote:
> If the maximum number of devices allowed on a bus is 1 and a device
> which is plugged into the bus is subsequently unplugged, attempting to replug
> the device fails with error "Bus 'xxx' does not support hotplugging".
> The "error" is detected in the qbus_is_full(BusState *bus) function
> (qdev_monitor.c) because bus->max_index >= bus_class->max_dev. The
> root of the problem is that the bus->max_index is not decremented when a device
> is unplugged from the bus. This patch fixes that problem.
I think that the root of the problem is that the max_index is not the
right measure to determine the number of devices currently plugged.
With the comment amended in this direction:
Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
> hw/core/qdev.c | 3 +++
> include/hw/qdev-core.h | 1 +
> qdev-monitor.c | 2 +-
> 3 files changed, 5 insertions(+), 1 deletion(-)
>
> 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++;
> 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;
> }
>
> /*
>
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device
2018-12-14 9:16 ` Pierre Morel
@ 2018-12-14 14:35 ` Tony Krowiak
0 siblings, 0 replies; 6+ messages in thread
From: Tony Krowiak @ 2018-12-14 14:35 UTC (permalink / raw)
To: pmorel, qemu-devel; +Cc: pasic, mammedo
On 12/14/18 4:16 AM, Pierre Morel wrote:
> On 13/12/2018 17:26, Tony Krowiak wrote:
>> If the maximum number of devices allowed on a bus is 1 and a device
>> which is plugged into the bus is subsequently unplugged, attempting to
>> replug
>> the device fails with error "Bus 'xxx' does not support hotplugging".
>> The "error" is detected in the qbus_is_full(BusState *bus) function
>> (qdev_monitor.c) because bus->max_index >= bus_class->max_dev. The
>> root of the problem is that the bus->max_index is not decremented when
>> a device
>> is unplugged from the bus. This patch fixes that problem.
>
> I think that the root of the problem is that the max_index is not the
> right measure to determine the number of devices currently plugged.
>
> With the comment amended in this direction:
Good point, I should have changed that when I refactored this fix.
>
> Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>
>
>
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> ---
>> hw/core/qdev.c | 3 +++
>> include/hw/qdev-core.h | 1 +
>> qdev-monitor.c | 2 +-
>> 3 files changed, 5 insertions(+), 1 deletion(-)
>>
>> 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++;
>> 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;
>> }
>>
>> /*
>>
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device
2018-12-13 16:26 [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device Tony Krowiak
2018-12-14 9:16 ` Pierre Morel
@ 2018-12-14 9:22 ` Pierre Morel
2018-12-14 12:09 ` Halil Pasic
2 siblings, 0 replies; 6+ messages in thread
From: Pierre Morel @ 2018-12-14 9:22 UTC (permalink / raw)
To: Tony Krowiak, qemu-devel; +Cc: pasic, imammedo
On 13/12/2018 17:26, Tony Krowiak wrote:
> If the maximum number of devices allowed on a bus is 1 and a device
> which is plugged into the bus is subsequently unplugged, attempting to replug
> the device fails with error "Bus 'xxx' does not support hotplugging".
> The "error" is detected in the qbus_is_full(BusState *bus) function
> (qdev_monitor.c) because bus->max_index >= bus_class->max_dev. The
> root of the problem is that the bus->max_index is not decremented when a device
> is unplugged from the bus. This patch fixes that problem.
I think that the root of the problem is that the max_index is not the
right measure to determine the number of devices currently plugged.
With the comment amended in this direction:
Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>
(resent after address correction)
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
> hw/core/qdev.c | 3 +++
> include/hw/qdev-core.h | 1 +
> qdev-monitor.c | 2 +-
> 3 files changed, 5 insertions(+), 1 deletion(-)
>
> 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++;
> 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;
> }
>
> /*
>
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device
2018-12-13 16:26 [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device Tony Krowiak
2018-12-14 9:16 ` Pierre Morel
2018-12-14 9:22 ` Pierre Morel
@ 2018-12-14 12:09 ` Halil Pasic
2018-12-14 14:36 ` Tony Krowiak
2 siblings, 1 reply; 6+ messages in thread
From: Halil Pasic @ 2018-12-14 12:09 UTC (permalink / raw)
To: Tony Krowiak; +Cc: qemu-devel, mammedo
On Thu, 13 Dec 2018 11:26:42 -0500
Tony Krowiak <akrowiak@linux.ibm.com> wrote:
> If the maximum number of devices allowed on a bus is 1 and a device
> which is plugged into the bus is subsequently unplugged, attempting to replug
> the device fails with error "Bus 'xxx' does not support hotplugging".
> The "error" is detected in the qbus_is_full(BusState *bus) function
> (qdev_monitor.c) because bus->max_index >= bus_class->max_dev. The
> root of the problem is that the bus->max_index is not decremented when a device
> is unplugged from the bus. This patch fixes that problem.
>
As Pierre has pointed out, the commit message is stale and inaccurate.
Subject could be better as well. I mean the problem is not limited to
buses that allow only one device. Each bus that can get full looses
capacity with every plug/unplug op pair. With that fixed:
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
> hw/core/qdev.c | 3 +++
> include/hw/qdev-core.h | 1 +
> qdev-monitor.c | 2 +-
> 3 files changed, 5 insertions(+), 1 deletion(-)
>
> 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++;
> 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;
> }
>
> /*
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Qemu-devel] [PATCH v2] qdev/core: Can not replug device on bus that allows one device
2018-12-14 12:09 ` Halil Pasic
@ 2018-12-14 14:36 ` Tony Krowiak
0 siblings, 0 replies; 6+ messages in thread
From: Tony Krowiak @ 2018-12-14 14:36 UTC (permalink / raw)
To: Halil Pasic; +Cc: qemu-devel, mammedo
On 12/14/18 7:09 AM, Halil Pasic wrote:
> On Thu, 13 Dec 2018 11:26:42 -0500
> Tony Krowiak <akrowiak@linux.ibm.com> wrote:
>
>> If the maximum number of devices allowed on a bus is 1 and a device
>> which is plugged into the bus is subsequently unplugged, attempting to replug
>> the device fails with error "Bus 'xxx' does not support hotplugging".
>> The "error" is detected in the qbus_is_full(BusState *bus) function
>> (qdev_monitor.c) because bus->max_index >= bus_class->max_dev. The
>> root of the problem is that the bus->max_index is not decremented when a device
>> is unplugged from the bus. This patch fixes that problem.
>>
>
> As Pierre has pointed out, the commit message is stale and inaccurate.
> Subject could be better as well. I mean the problem is not limited to
> buses that allow only one device. Each bus that can get full looses
> capacity with every plug/unplug op pair. With that fixed:
>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
I'll make the changes recommended by you and Pierre.
>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> ---
>> hw/core/qdev.c | 3 +++
>> include/hw/qdev-core.h | 1 +
>> qdev-monitor.c | 2 +-
>> 3 files changed, 5 insertions(+), 1 deletion(-)
>>
>> 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++;
>> 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;
>> }
>>
>> /*
>
^ permalink raw reply [flat|nested] 6+ messages in thread