[libvirt] [PATCH RFC] Add domainSave/Restore to libxl driver

[Markus Groß]

Quoting Jim Fehlig <jfehlig at novell.com>:

> Markus Groß wrote:
>> Am Dienstag 24 Mai 2011 06:06:08 schrieb Jim Fehlig:
>>
>>>> +
>>>> +        event = virDomainEventNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
>>>> +                                         VIR_DOMAIN_EVENT_STOPPED_SAVED);
>>>> +
>>>> +        if (libxlVmReap(driver, vm, 1, VIR_DOMAIN_SHUTOFF_SAVED) != 0) {
>>>> +            libxlError(VIR_ERR_INTERNAL_ERROR,
>>>> +                       _("Failed to destroy domain '%d'"), dom->id);
>>>> +            goto cleanup;
>>>> +        }
>>>>
>>>>
>>> And here call libxl_domain_destroy() directly instead of libxlVmReap(),
>>> allowing the event handler to cleanup the vm.
>>>
>>> Can you make these changes and ensure all the save/restore issues are
>>> resolved in your environment?
>>>
>>
>> I made these changes but this leads to another issue.
>> When using the event handler to cleanup the domain
>> there seems to be a race condition.
>> The call to libxl_event_get_domain_death_info returns a value != 1
>>
>
> That should be fine though.  libxl_event_get_domain_death_info() will
> return 1 if the event is for the specified domid.  If it returns a value
> != 1, we goto cleanup and keep listening.
>
>> sometimes and the domain gets not cleaned up.
>>
>
> Did you use the force flag when invoking
> libxl_event_get_domain_death_info()?  I've noticed that no events are
> generated when using that flag.

Yes, I used the force flag.

>
>> The latest version of the patch I posted in this thread earlier does
>> not have this issue as it cleans up the domain directly.
>>
>
> How about this adjustment to your latest version?  I can't find any
> issues using this change, and it follows the same pattern used in xl client.
>

I experienced the described behavior using this adjustment, except  
that I used the force flag. I will test the patch again without using  
the force flag and will repost it. Unfortunately that has to wait till  
monday as I am out of the office now.

Cheers,
Markus

> --- a/src/libxl/libxl_driver.c
> +++ b/src/libxl/libxl_driver.c
> @@ -378,6 +378,9 @@ static void libxlEventHandler(int watch,
>                  libxlVmReap(driver, vm, 0, VIR_DOMAIN_SHUTOFF_SHUTDOWN);
>                  libxlVmStart(driver, vm, 0, -1);
>                  break;
> +            case SHUTDOWN_suspend:
> +                libxlVmCleanup(driver, vm, VIR_DOMAIN_SHUTOFF_SAVED);
> +                break;
>              default:
>                  VIR_INFO("Unhandled shutdown_reason %d",
> info.shutdown_reason);
>                  break;
> @@ -1719,7 +1722,7 @@ libxlDomainSave(virDomainPtr dom, const char *to)
>          event = virDomainEventNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
>                                           VIR_DOMAIN_EVENT_STOPPED_SAVED);
>
> -        if (libxlVmReap(driver, vm, 1, VIR_DOMAIN_SHUTOFF_SAVED) != 0) {
> +        if (libxl_domain_destroy(&priv->ctx, dom->id, 0) < 0) {
>              libxlError(VIR_ERR_INTERNAL_ERROR,
>                         _("Failed to destroy domain '%d'"), dom->id);
>              goto cleanup;
>
>