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

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(a)invisiblethingslab.com&gt; >>>> --- >>>> 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.