Re: [libvirt] [Xen-devel] [FOR 1.3.0 PATCH] conf: add net device prefix for Xen

On 12/08/2015 04:06 PM, Jim Fehlig wrote: > Daniel P. Berrange wrote: >> On Mon, Dec 07, 2015 at 10:59:32PM -0700, Jim Fehlig wrote: >>> On 12/07/2015 11:52 AM, Daniel P. Berrange wrote: >>>> On Mon, Dec 07, 2015 at 09:42:21AM -0700, Jim Fehlig wrote: >>>>> In commit d2e5538b1, the libxl driver was changed to copy interface >>>>> names autogenerated by libxl to the corresponding network def in the >>>>> domain's virDomainDef object. The copied name is freed when the domain >>>>> transitions to the shutoff state. But when migrating a domain, the >>>>> autogenerated name is included in the XML sent to the destination host. >>>>> It is possible an interface with the same name already exists on the >>>>> destination host, causing migration to fail. Indeed the Xen project's >>>>> OSSTEST CI already encountered such a failure. >>>>> >>>>> This patch defines another VIR_NET_GENERATED_PREFIX for Xen, allowing >>>>> the autogenerated names to be excluded when parsing and formatting >>>>> inactive config. >>>>> >>>>> Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; >>>>> --- >>>>> >>>>> This is an alternative approach to Joao's fix for this regression >>>>> >>>>> https://www.redhat.com/archives/libvir-list/2015-December/msg00197.html >>>>> >>>>> I think it is the same approach used by the qemu driver. My only >>>>> reservation is that it expands the potential for clashes with >>>>> user-defined names. I.e. with this change both 'vnet' and 'vif' are >>>>> reserved prefixes. >>>> Hmm, yes, tricky one. >>>> >>>> If we only care about XML parsing, then you could register a post >>>> parse callback instead to do this. >>> AFAIK, XML parsing is all that's in play here. >>> >>>> I'm not clear why we also have it in the virDomainNetDefFormat >>>> method - and we can't solve that with a post-parse callback. >>>> >>>> >>>> The other option would be to make the reserved prefix be a >>>> capability that the parser/formatter could read. >>> This seems like the best option, since a post-parse callback doesn't solve the >>> problem in virDomainNetDefFormat. It also has the upshot of making the prefix >>> visible and known to users. But I doubt such a change is suitable during 1.3.0 >>> freeze. With the freeze in mind, seems the best solution to the libxl migration >>> regression is revert d2e5538b1. It can be added again post-1.3.0 release, after >>> adding the prefix to capabilities. >>> >>> DV, since you may be making the release soon, feel free to revert d2e5538b1 if >>> you agree. >> Yeah, just go ahead & revert it Jim, DV isn't doing the releae until >> tomorrow morning > I've pushed the revert. > > Joao, sorry for yanking this for 1.3.0. We can get it in 1.3.1, after exposing > the prefix in capabilities. > Hey Jim, I had the impression we had pushed this back in (i.e. cherry-picking d2e5538) but I was double checking and that's doesn't seem to be case. In adding support for the prefix in capabilities I found out one issue on the migration failure path leading to dereferencing a NULL pointer on the destination. If you agree could we squash the following chunk in addition to the cherry-pick of d2e5538: diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c index 63c5b24..f73bfb3 100644 --- a/src/libxl/libxl_domain.c +++ b/src/libxl/libxl_domain.c @@ -768,7 +768,7 @@ libxlDomainCleanup(libxlDriverPrivatePtr driver, for (i = 0; i < vm->def->nnets; i++) { virDomainNetDefPtr net = vm->def->nets[i]; - if (STRPREFIX(net->ifname, "vif")) + if (net->ifname && STRPREFIX(net->ifname, "vif")) VIR_FREE(net->ifname); } } diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c index 3f4457f..5479441 100644 --- a/src/libxl/libxl_driver.c +++ b/src/libxl/libxl_driver.c @@ -5590,7 +5590,7 @@ static virHypervisorDriver libxlHypervisorDriver = { .domainGetJobStats = libxlDomainGetJobStats, /* 1.3.1 */ .domainMemoryStats = libxlDomainMemoryStats, /* 1.3.0 */ .domainGetCPUStats = libxlDomainGetCPUStats, /* 1.3.0 */ - .domainInterfaceStats = libxlDomainInterfaceStats, /* 1.3.0 */ + .domainInterfaceStats = libxlDomainInterfaceStats, /* 1.3.2 */ .connectDomainEventRegister = libxlConnectDomainEventRegister, /* 0.9.0 */ .connectDomainEventDeregister = libxlConnectDomainEventDeregister, /* 0.9.0 */ .domainManagedSave = libxlDomainManagedSave, /* 0.9.2 */ Or do you think it should be deferred to 1.3.3 ?