[libvirt] [PATCH 4/5] conf: make sure that chardev reconnect is formatted only for connect mode

[Michal Privoznik]

On 08/30/2017 02:54 PM, Pavel Hrdina wrote:
> On Wed, Aug 30, 2017 at 02:32:50PM +0200, Michal Privoznik wrote:
>> On 08/30/2017 01:40 PM, Pavel Hrdina wrote:
>>> Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
>>> ---
>>>  src/conf/domain_conf.c | 10 ++++++----
>>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>>> index f7574d77b6..7f443e5b4d 100644
>>> --- a/src/conf/domain_conf.c
>>> +++ b/src/conf/domain_conf.c
>>> @@ -23257,8 +23257,9 @@ virDomainChrSourceDefFormat(virBufferPtr buf,
>>>              virBufferAsprintf(&attrBuf, " tlsFromConfig='%d'",
>>>                                def->data.tcp.tlsFromConfig);
>>>  
>>> -        virDomainChrSourceReconnectDefFormat(&childBuf,
>>> -                                             &def->data.tcp.reconnect);
>>> +        if (!def->data.tcp.listen)
>>> +            virDomainChrSourceReconnectDefFormat(&childBuf,
>>> +                                                 &def->data.tcp.reconnect);
>>>  
>>>          if (virXMLFormatElement(buf, "source", &attrBuf, &childBuf) < 0)
>>>              goto error;
>>> @@ -23276,8 +23277,9 @@ virDomainChrSourceDefFormat(virBufferPtr buf,
>>>              virDomainSourceDefFormatSeclabel(&childBuf, def->nseclabels,
>>>                                               def->seclabels, flags);
>>>  
>>> -            virDomainChrSourceReconnectDefFormat(&childBuf,
>>> -                                                 &def->data.nix.reconnect);
>>> +            if (!def->data.nix.listen)
>>> +                virDomainChrSourceReconnectDefFormat(&childBuf,
>>> +                                                     &def->data.nix.reconnect);
>>>  
>>>              if (virXMLFormatElement(buf, "source", &attrBuf, &childBuf) < 0)
>>>                  goto error;
>>>
>>
>> This looks like a workaround. Because def->data.tcp.listen shouldn't be
>> set if reconnect is enabled and vice versa. And
>> virDomainChrSourceReconnectDefFormat() shortcuts out. Or you want the
>> following:
>>
>>     <channel type='tcp'>
>>       <source mode='bind' host='localhost' service='5678'>
>>         <reconnect enabled='no'/>
>>       </source>
>>       <target type='virtio' name='test2'/>
>>     </channel>
>>
>> to be turned into:
>>
>>     <channel type='tcp'>
>>       <source mode='bind' host='localhost' service='5678'/>
>>       <target type='virtio' name='test2'/>
>>     </channel>
>>
>> Michal
> 
> Yes, it's kind of workaround for the case where you will set
> 
>   <channel type='unix'>
>     <source mode='connect' path='/var/lib/libvirt/qemu/channel/target/domain-test/test2'>
>       <reconnect enabled='no'/>
>     </source>
>     <target type='virtio' name='test2'/>
>   </channel>
> 
> Without this patch it would lead to:
> 
>   <channel type='unix'>
>     <source mode='bind' path='/var/lib/libvirt/qemu/channel/target/domain-5-test/test2'>
>       <reconnect enabled='no'/>
>     </source>
>     <target type='virtio' name='test2'/>
>   </channel>
> 
> because we remove the auto-generated path and while starting a guest
> we generate a new one and sets the mode to "bind".
> 
> This patch makes sure that in this case the XML of live guest is
> correct.
> 
> The proper fix would be to update _virDomainChrSourceDef by changing
> 'bool listen' into 'virDomainChrSourceModeType mode' and the parse would
> properly store three different values: default, connect, bind.  This
> would require rewrite a lot of code which is not suitable for a freeze,
> therefore this workaround.  I'm planning to fix it properly so that
> workaround is not required anymore.

Exactly. So what are we worried more about? Pushing this temporal
workaround or having not nice looking, but still valid and sensible XML?
Technically, mode='bind' and reconnect='no' is a valid combination.

Michal