[libvirt] [PATCH 07/10] libxl: prevent attaching multiple netdevs with the same MAC

[Marek Marczykowski-Górecki]

On Thu, Feb 19, 2015 at 01:58:02PM -0700, Jim Fehlig wrote:
> Marek Marczykowski-Górecki wrote:
> > On Thu, Feb 19, 2015 at 11:43:15AM -0700, Jim Fehlig wrote:
> >   
> >> Marek Marczykowski-Górecki wrote:
> >>     
> >>> It will not be possible to detach such device later. Also improve
> >>> logging in such cases.
> >>>
> >>> Signed-off-by: Marek Marczykowski-Górecki <marmarek at invisiblethingslab.com>
> >>> ---
> >>>  src/libxl/libxl_driver.c | 41 +++++++++++++++++++++++++++++++++++++++--
> >>>  1 file changed, 39 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
> >>> index ce3a99b..005cc96 100644
> >>> --- a/src/libxl/libxl_driver.c
> >>> +++ b/src/libxl/libxl_driver.c
> >>> @@ -2787,6 +2787,7 @@ libxlDomainAttachNetDevice(libxlDriverPrivatePtr driver,
> >>>      int actualType;
> >>>      libxl_device_nic nic;
> >>>      int ret = -1;
> >>> +    char mac[VIR_MAC_STRING_BUFLEN];
> >>>  
> >>>      /* preallocate new slot for device */
> >>>      if (VIR_REALLOC_N(vm->def->nets, vm->def->nnets + 1) < 0)
> >>> @@ -2801,6 +2802,14 @@ libxlDomainAttachNetDevice(libxlDriverPrivatePtr driver,
> >>>  
> >>>      actualType = virDomainNetGetActualType(net);
> >>>  
> >>> +    /* -2 means "multiple matches" so then fail also */
> >>>   
> >>>       
> >> No longer true after commit 2fbae1b2.  I think you just want to check if
> >> virDomainNetFindIdx() >= 0, meaning the def already contains a net
> >> device with the same mac address.
> >>     
> >
> > But here the error is when the device *is* found, so the opposite case
> > than already reported as an error by virDomainNetFindIdx.
> 
> If you find an idx >= 0, then the domain def already contains a net
> device with the same mac address, right?  In that case, you report an
> error and return failure from libxlDomainAttachNetDevice().

Right, but if I do not find one (idx == -1), I will proceed with
(possibly successful) adding the device, while the error was already
reported by virDomainNetFindIdx.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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