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

[Laine Stump]

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?