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

[Pavel Hrdina]

On Wed, Aug 30, 2017 at 03:38:13PM +0200, Michal Privoznik wrote:
> 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.

The thing is that this also formats

  <reconnect enabled='yes' timeout='10'/>

for "bind" mode which is wrong and needs to be fixed.

BTW: this is same workaround as for the qemu command line format code.

Pavel
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