[libvirt] [PATCH] qemu: Always refresh capabilities if no <guests> found (bz 1000116)

[Cole Robinson]

On 04/21/2015 10:13 AM, Michal Privoznik wrote:
> On 16.04.2015 21:08, Cole Robinson wrote:
>> - Remove all qemu emulators
>> - Restart libvirtd
>> - Install qemu emulators
>> - Call 'virsh version' -> errors
>>
>> The only thing that will force the qemu driver to refresh it's cached
>> capablities info is an explict API call to GetCapabilities.
>>
>> However in the case when the initial caps lookup at driver connect didn't
>> find a single qemu emulator to poll, the driver is effectively useless
>> and really can't do anything until it's populated some qemu capabilities
>> info.
>>
>> With the above steps, the user would have to either know about the
>> magic refresh capabilities call, or restart libvirtd to pick up the
>> changes.
>>
>> Instead, this patch changes things so that every time a part of th
>> driver requests access to capabilities info, check to see if
>> we've previously seen any emulators. If not, force a refresh.
>>
>> In the case of 'still no emulators found', this is still very quick, so
>> I can't think of a downside.
>>
>> https://bugzilla.redhat.com/show_bug.cgi?id=1000116
>> ---
>>  src/qemu/qemu_conf.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
>> index 2cf3905..b662b69 100644
>> --- a/src/qemu/qemu_conf.c
>> +++ b/src/qemu/qemu_conf.c
>> @@ -965,6 +965,13 @@ virCapsPtr virQEMUDriverGetCapabilities(virQEMUDriverPtr driver,
>>          qemuDriverLock(driver);
>>      }
>>  
>> +    if (driver->caps->nguests == 0 && !refresh) {
>> +        VIR_DEBUG("Capabilities didn't detect any guests. Forcing a "
>> +            "refresh.");
>> +        qemuDriverUnlock(driver);
>> +        return virQEMUDriverGetCapabilities(driver, true);
>> +    }
>> +
>>      ret = virObjectRef(driver->caps);
>>      qemuDriverUnlock(driver);
>>      return ret;
>>
> 
> ACK, although I'd remove "(bz ...)" from the $subj and keep the BZ link
> in the commit message.
> 

Thanks, pushed now with that tweak

- Cole