Re: [libvirt] [PATCH] qemuOpenVhostNet: Decrease vhostfdSize on open failure

On 05/24/2013 08:50 AM, Michal Privoznik wrote: > Currently, if there's an error opening /dev/vhost-net (e.g. because > it doesn't exist) but it's not required we proceed with vhostfd array > filled with -1 and vhostfdSize unchanged. Later, when constructing > the qemu command line only non-negative items within vhostfd array > are taken into account. This means, vhostfdSize may be greater than > the actual count of non-negative items in vhostfd array. This results > in improper command line arguments being generated, e.g.: > > -netdev tap,fd=21,id=hostnet0,vhost=on,vhostfd=(null) > --- > src/qemu/qemu_command.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index 434f5a7..d969f88 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > @@ -486,6 +486,8 @@ qemuOpenVhostNet(virDomainDefPtr def, > "but is unavailable")); > goto error; > } > + i--; > + (*vhostfdSize)--; This will still go back through the loop again and try to open another. I would instead just set vhostfdSize = i (in case there were any successful opens) and break out of the loop. And again you'll need to decide what is an error and what gets just a warning - if someone asks for 3 queues and gets none, that should lead to continuing without any error or even warning. But if they request 2 and only get one, is that an error, or do we warn and continue? or just silently continue? (I don't have the answer, I'm just asking the question :-)

> } > } > virDomainAuditNetDevice(def, net, "/dev/vhost-net", *vhostfdSize); > @@ -6560,12 +6562,10 @@ qemuBuildInterfaceCommandLine(virCommandPtr cmd, > } > > for (i = 0; i < vhostfdSize; i++) { > - if (vhostfd[i] >= 0) { > - virCommandTransferFD(cmd, vhostfd[i]); > - if (virAsprintf(&vhostfdName[i], "%d", vhostfd[i]) < 0) { > - virReportOOMError(); > - goto cleanup; > - } > + virCommandTransferFD(cmd, vhostfd[i]); > + if (virAsprintf(&vhostfdName[i], "%d", vhostfd[i]) < 0) { > + virReportOOMError(); > + goto cleanup; > } > } > -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list