> On Mon, Sep 17, 2018 at 06:53:13PM +0800, wang.yi59@xxxxxxxxxx wrote:
> > > On Sat, Sep 15, 2018 at 04:29:24PM +0800, Yi Wang wrote:
> > > > Domain fails to start when its config xml including:
> > > > <vcpu cpuset="" current="8">64</vcpu>
> > > >
> > > > # virsh create vm.xml
> > > > error: Failed to create domain from vm.xml
> > > > error: invalid argument: Failed to parse bitmap ''
> > > >
> > > > This patch fixes this.
> > > >
> > > > Signed-off-by: Yi Wang <wang.yi59@xxxxxxxxxx>
> > > > Reviewed-by: Xi Xu <xu.xi8@xxxxxxxxxx>
> > > > ---
> > > > src/conf/domain_conf.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> > > > index 8619962..bacafb2 100644
> > > > --- a/src/conf/domain_conf.c
> > > > +++ b/src/conf/domain_conf.c
> > > > @@ -18553,7 +18553,7 @@ virDomainVcpuParse(virDomainDefPtr def,
> > > >
> > > > if (def->placement_mode != VIR_DOMAIN_CPU_PLACEMENT_MODE_AUTO) {
> > > > tmp = virXMLPropString(vcpuNode, "cpuset");
> > > > - if (tmp) {
> > > > + if (tmp && strlen(tmp) != 0) {
> > >
> > > .... '&& *tmp' would suffice.
> >
> > Ok.
> >
> > >
> > > The patch is correct, but I believe there is a number of spots in the massive
> > > domain_conf.c file where a similar fix would be needed, it might be worth
> > > checking all the spots where no conversion like string-to-int string-to-enum or
> > > any other additional parsing like address parsing is performed, those might be
> > > good candidates.
> > >
> > > I understand the file is massive, so let me know how that goes.
> >
> > In most similar places we have already checked by the return values of function
> > like string-to-int string-to-enum, and if failed, libvirt will give explicit report.
> >
> > To create a domain with iothread="" of disk, for instance:
> >
> > # virsh create vm.xml
> > error: Failed to create domain from vm.xml
> > error: XML error: Invalid iothread attribute in disk driver element:
> >
> > But the cpuset="" config error report may make people confuesd, and in the older
> > version like 3.1.0 that's ok to start a domain with this config. So I think this patch
> > is enough.
>
> So, I thought about this quite a bit. The fact that 3.1.0 was okay with that
> was because commit b71946af5c7 changed the helper we use during parsing. The
> original one considered NULL and foo[0] == '\0' to be the same and always
> returned NULL. However, now that I looked at the code more closely, I don't
> think we want this patch, in fact, an empty cpuset is an invalid attribute,
> what's the point of having an empty cpuset vs not having it at all, if you don't
> want static pinning then don't specify one, there's no practical use case in
> that. That being said, I also find the error very generic and vague, so if
> anyone wants to actually figure out what the part causing problems in the XML
> parsing is, they have no chance, we should improve that. Paradoxically, we had
> that back in 2013 until commit 106a2ddaa7b changed it with absolutely no
> rationale or a corresponding BZ on why decreasing user experience was a good
> idea, I know, rather a rare use case what you have here, but still, why is okay
> to parse numbers from string with no error, thus giving a clear error (like your
> iothread example), but not okay for bitmaps, CC'ing Peter to give more
> information about that change.
I have checked the commit b71946af5c7 before sending this patch and came up with two solutions:
- make cpuset="" passed the check, like this patch does
- add specified error report, rather than complaining about parsing bitmap
The first method can keep consistence with the older version, so I chose this one.
---
Best wishes
Yi Wang--
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