Re: [libvirt] [PATCH v2] qemuOpenVhostNet: Decrease vhostfdSize on open failure

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 | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 0373626..c4a162a 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -486,6 +486,10 @@ qemuOpenVhostNet(virDomainDefPtr def, "but is unavailable")); goto error; } + VIR_WARN("Unable to open vhost-net. Opened so far %d, requested %d", + i, *vhostfdSize); + *vhostfdSize = i; + break; } } virDomainAuditNetDevice(def, net, "/dev/vhost-net", *vhostfdSize); @@ -6560,12 +6564,10 @@ 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; } }