Re: [libvirt] [PATCH] qemu: hotplug: unify "not found" logs when detaching device

On 12/15/2017 09:50 PM, Chen Hanxiao wrote: > > > At 2017-12-16 09:26:32, "John Ferlan" <jferlan(a)redhat.com&gt; wrote: >> >> >> On 12/14/2017 06:16 AM, Chen Hanxiao wrote: >>> From: Chen Hanxiao <chenhanxiao(a)gmail.com&gt; >>> >>> Some services, such as Nova, check whether device was not found >>> by errror messages "not found". [1] >> >> error >> >>> >>> This patch unify logs of qemuDomainDetachDeviceLive, which will be helpful. >>> >>> [1] https://github.com/openstack/nova/blob/master/nova/virt/libvirt/guest.py#... >>> >>> Signed-off-by: Chen Hanxiao <chenhanxiao(a)gmail.com&gt; >>> --- >>> src/qemu/qemu_hotplug.c | 18 +++++++++++------- >>> 1 file changed, 11 insertions(+), 7 deletions(-) >>> >> >> Something about a tool that parses the error message(s) looking for a >> specific message string in English and needing to alter libvirt sources >> to match that tools' needs strikes me as incorrect and a "slippery >> slope" to follow. >> >> I'm not in favor of this because we'll be constantly chasing these types >> of bugs to match some other tools' (what I think is) incorrect means to >> handle errors. >> > > Agree. > But we don't have enough error code to cover all of scenario. > Then there'd be a "different" fix required - adding an error code... Perhaps VIR_ERR_NO_DEVICE which would have error text "device %s not found"?

Of course that would require up the stack source code changes as well. Still better than scanning the error message which only works for a specific language set. IOW: how would this work for non "English" languages? > For qemuDomainDetachDeviceDiskLive, VIR_ERR_OPERATION_FAILED can be > "disk not found", also can be "cannot hot unplug multifunction PCI device" > in the following call of qemuDomainDetachVirtioDiskDevice. So it's "OK" to have a different operational failure? I assume that'll cause a failure elsewhere in the code. I didn't go digging on the source code - just a quick look at the _try_detach_device method from the above nova link. > > So the tools powered by libvirt had to find a workaround by > analyzing error messages... Again, wouldn't those tools be broken without the right language set being used?