[libvirt] [PATCH v3] network: Bring netdevs online later

[Matthew Rosato]

On 12/11/2014 01:35 PM, Laine Stump wrote:
> On 09/16/2014 04:50 PM, Matthew Rosato wrote:
>>  
>>  #include "cpu/cpu.h"
>>  #include "datatypes.h"
>> @@ -2947,6 +2948,12 @@ qemuProcessStartCPUs(virQEMUDriverPtr driver, virDomainObjPtr vm,
>>      qemuDomainObjPrivatePtr priv = vm->privateData;
>>      virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
>>  
>> +    /* Bring up netdevs before starting CPUs */
>> +    if (reason != VIR_DOMAIN_RUNNING_UNPAUSED &&
>> +        reason != VIR_DOMAIN_RUNNING_SAVE_CANCELED) {
>> +        qemuInterfaceStartDevices(vm->def);
>> +    }
> Matthew,
> 
> 
> I've already pushed your patch, but am trying to add to it for another
> related purpose and this bit is bothering me. What is the reason for not
> calling qemuInterfaceStartDevices() when reason is
> VIR_DOMAIN_RUNNING_UNPAUSED or VIR_DOMAIN_RUNNING_SAVE_CANCELED? Is it
> just to avoid setting IFF_UP on an interface that is already IFF_UP?
> 
> If that's the only reason, I would prefer to have it *always* called
> when the CPUs are started (and a corresponding
> qemuInterfaceStopDevices() called when the CPUs are stopped). Otherwise,
> it looks to me like it is possible in some situations (migration error
> recovery perhaps? search for VIR_DOMAIN_RUNNING_UNPAUSED) to have the
> CPUs running, but the macvtap interfaces *not* IFF_UP.
> 
> Do you see (or did you experience?) a problem calling
> qemuInterfaceStartDevices() for all reasons?
> 

Hi Laine,

I did not experience any problems calling qemuInterfaceStartDevices()
unconditionally, that's actually how I originally wrote the code -- I
added these conditional statements based on a review comment to avoid
unnecessary IFF_UPs.

I'd be fine with the call being unconditional again.

Matt