> On Apr 22, 2022, at 1:18 AM, Markus Armbruster <arm...@redhat.com> wrote:
>
> Jag Raman <jag.ra...@oracle.com> writes:
>
>>> On Apr 21, 2022, at 10:55 AM, Markus Armbruster <arm...@redhat.com> wrote:
>>>
>>> Jagannathan Raman <jag.ra...@oracle.com> writes:
>>>
>>>> Add blocker to prevent hot-unplug of devices
>>>
>>> Why do you need this? I'm not doubting you do, I just want to read your
>>> reasons here :)
>>
>> Hi Markus, :)
>>
>> The x-vfio-user-server depends on an attached PCIDevice. As long as
>> x-vfio-user-server
>> is used, we don’t want the PCIDevice to be unplugged. This blocker prevents
>> an user
>> from removing PCIDevice while the vfio-user server is in use.
>
> Please work that into your commit message. Perhaps along the lines of
>
> One of the next commits will do <stuff>. <badness> will happen when
> the PCI device is unplugged. Create the means to prevent that.
OK, will do.
Thank you!
--
Jag
>
>>>> Signed-off-by: Elena Ufimtseva <elena.ufimts...@oracle.com>
>>>> Signed-off-by: John G Johnson <john.g.john...@oracle.com>
>>>> Signed-off-by: Jagannathan Raman <jag.ra...@oracle.com>
>>
>> I recall receiving a “Reviewed-by” from Stefan previously.
>>
>> I’m very sorry I didn’t add that here. I’ll go over all the patches once
>> again to confirm that
>> the “Reviewed-by” status reflects accurately.
>>
>>>> ---
>>>> include/hw/qdev-core.h | 29 +++++++++++++++++++++++++++++
>>>> hw/core/qdev.c | 24 ++++++++++++++++++++++++
>>>> softmmu/qdev-monitor.c | 4 ++++
>>>> 3 files changed, 57 insertions(+)
>>>>
>>>> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
>>>> index 92c3d65208..1b9fa25e5c 100644
>>>> --- a/include/hw/qdev-core.h
>>>> +++ b/include/hw/qdev-core.h
>>>> @@ -193,6 +193,7 @@ struct DeviceState {
>>>> int instance_id_alias;
>>>> int alias_required_for_version;
>>>> ResettableState reset;
>>>> + GSList *unplug_blockers;
>>>> };
>>>>
>>>> struct DeviceListener {
>>>> @@ -419,6 +420,34 @@ void qdev_simple_device_unplug_cb(HotplugHandler
>>>> *hotplug_dev,
>>>> void qdev_machine_creation_done(void);
>>>> bool qdev_machine_modified(void);
>>>>
>>>> +/*
>>>> + * qdev_add_unplug_blocker: Adds an unplug blocker to a device
>>>> + *
>>>> + * @dev: Device to be blocked from unplug
>>>> + * @reason: Reason for blocking
>>>> + */
>>>> +void qdev_add_unplug_blocker(DeviceState *dev, Error *reason);
>>>> +
>>>> +/*
>>>> + * qdev_del_unplug_blocker: Removes an unplug blocker from a device
>>>> + *
>>>> + * @dev: Device to be unblocked
>>>> + * @reason: Pointer to the Error used with qdev_add_unplug_blocker.
>>>> + * Used as a handle to lookup the blocker for deletion.
>>>> + */
>>>> +void qdev_del_unplug_blocker(DeviceState *dev, Error *reason);
>>>> +
>>>> +/*
>>>> + * qdev_unplug_blocked: Confirms if a device is blocked from unplug
>>>> + *
>>>> + * @dev: Device to be tested
>>>> + * @reason: Returns one of the reasons why the device is blocked,
>>>> + * if any
>>>> + *
>>>> + * Returns: true if device is blocked from unplug, false otherwise
>>>> + */
>>>> +bool qdev_unplug_blocked(DeviceState *dev, Error **errp);
>>>> +
>>>> /**
>>>> * GpioPolarity: Polarity of a GPIO line
>>>> *
>>>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>>>> index 84f3019440..0806d8fcaa 100644
>>>> --- a/hw/core/qdev.c
>>>> +++ b/hw/core/qdev.c
>>>> @@ -468,6 +468,28 @@ char *qdev_get_dev_path(DeviceState *dev)
>>>> return NULL;
>>>> }
>>>>
>>>> +void qdev_add_unplug_blocker(DeviceState *dev, Error *reason)
>>>> +{
>>>> + dev->unplug_blockers = g_slist_prepend(dev->unplug_blockers, reason);
>>>> +}
>>>> +
>>>> +void qdev_del_unplug_blocker(DeviceState *dev, Error *reason)
>>>> +{
>>>> + dev->unplug_blockers = g_slist_remove(dev->unplug_blockers, reason);
>>>> +}
>>>> +
>>>> +bool qdev_unplug_blocked(DeviceState *dev, Error **errp)
>>>> +{
>>>> + ERRP_GUARD();
>>>> +
>>>> + if (dev->unplug_blockers) {
>>>> + error_propagate(errp, error_copy(dev->unplug_blockers->data));
>>>> + return true;
>>>> + }
>>>> +
>>>> + return false;
>>>> +}
>>>
>>> This cites the most recently added blocker as reason. Your function
>>> comment covers it: "Returns one of the reasons". Okay.
>>
>> I could change the comment to say that it returns the recently added reason.
>
> Up to you.
>
