Re: [libvirt] [PATCH 5/5] qemu: launch bridge helper from libvirtd
On 04/18/2013 11:32 AM, Laine Stump wrote:
On 03/25/2013 10:25 AM, Paolo Bonzini wrote:
> <source type='bridge'> uses a helper application to do the necessary
> TUN/TAP setup to use an existing network bridge, thus letting
> unprivileged users use TUN/TAP interfaces.
>
> @@ -3746,7 +3828,6 @@ error:
> char *
> qemuBuildHostNetStr(virDomainNetDefPtr net,
> virQEMUDriverPtr driver,
> - virQEMUCapsPtr qemuCaps,
qemuCaps might again become useful for this function in the future, so
you may want to leave it here (marked as ATTRIBUTE_UNUSED) to reduce
code churn.
For that matter, do we need a qemu capability bit that says whether the
bridge helper even exists, or do you give a nice error message to
someone using qemu:///session on a machine with too-old qemu without the
need for a capability bit??
I still don't like using qemu-bridge-helper, but this is better than the
alternative of having qemu call it (although, due to the way that
process capabilities works, we are unable to prevent a rogue qemu
started by unprivileged libvirtd from calling it :-(
ACK to this patch (I think I would prefer you left the qemuCaps arg in,
but others may disagree with me.)
I haven't pushed 4 or 5 (4 needed an OOM fix, and there's the question
of whether a capability bit is still useful). I don't have a strong
preference whether to leave qemuCaps in; we have version control to
inspect if we need to figure out how to add it back in later. I prefer
to limit ATTRIBUTE_UNUSED markers to functions that have a required
signature (generally, callbacks to be called from some other generic
code site); but this doesn't feel like we have any reason to be locked
into leaving qemuCaps in the interface.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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