[libvirt] [PATCH 11/14] Remove the network backend if NIC hotplug fails

[Daniel P. Berrange]

On Mon, Jul 20, 2009 at 12:51:21PM +0100, Mark McLoughlin wrote:
> If we fail to pci_add a NIC, we should remove the network backend and
> leave things the way we found them. To do that, we pre-allocate a
> host_net_remove monitor command and issue that if the pci_add fails.
> If the remove fails, we just log a warning.
> 
> We can only do this if we have a name for the network backend and
> we know the vlan number its associated with.
> 
> * src/qemu_driver.c: host_net_remove the network backend if the
>   pci_add fails
> ---
>  src/qemu_driver.c |   35 ++++++++++++++++++++++++++++-------
>  1 files changed, 28 insertions(+), 7 deletions(-)
> 
> diff --git a/src/qemu_driver.c b/src/qemu_driver.c
> index cde789e..4cc78f5 100644
> --- a/src/qemu_driver.c
> +++ b/src/qemu_driver.c
> @@ -4498,7 +4498,7 @@ static int qemudDomainAttachNetDevice(virConnectPtr conn,
>                                        unsigned int qemuCmdFlags)
>  {
>      virDomainNetDefPtr net = dev->data.net;
> -    char *cmd, *reply;
> +    char *cmd, *reply, *remove_cmd;
>      int i;
>  
>      if (!(qemuCmdFlags & QEMUD_CMD_FLAG_HOST_NET_ADD)) {
> @@ -4538,9 +4538,19 @@ static int qemudDomainAttachNetDevice(virConnectPtr conn,
>                              "host_net_add ", ' ', net->vlan, -1, &cmd) < 0)
>          return -1;
>  
> +    remove_cmd = NULL;
> +    if (net->vlan >= 0 && net->hostnet_name &&
> +        virAsprintf(&remove_cmd, "host_net_remove %d %s",
> +                    net->vlan, net->hostnet_name) < 0) {
> +        VIR_FREE(cmd);
> +        virReportOOMError(conn);
> +        return -1;
> +    }
> +
>      if (qemudMonitorCommand(vm, cmd, &reply) < 0) {
>          qemudReportError(conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
>                           _("failed to add network backend with '%s'"), cmd);
> +        VIR_FREE(remove_cmd);
>          VIR_FREE(cmd);
>          return -1;
>      }
> @@ -4549,25 +4559,36 @@ static int qemudDomainAttachNetDevice(virConnectPtr conn,
>      VIR_FREE(cmd);
>  
>      if (qemuBuildNicStr(conn, net,
> -                        "pci_add pci_addr=auto ", ' ', net->vlan, &cmd) < 0) {
> -        /* FIXME: try and remove the backend again */
> -        return -1;
> -    }
> +                        "pci_add pci_addr=auto ", ' ', net->vlan, &cmd) < 0)
> +        goto try_remove;
>  
>      if (qemudMonitorCommand(vm, cmd, &reply) < 0) {
> -        /* FIXME: try and remove the backend again */
>          qemudReportError(conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
>                           _("failed to add NIC with '%s'"), cmd);
>          VIR_FREE(cmd);
> -        return -1;
> +        goto try_remove;
>      }
>  
>      VIR_FREE(reply);
>      VIR_FREE(cmd);
> +    VIR_FREE(remove_cmd);
>  
>      vm->def->nets[vm->def->nnets++] = net;
>  
>      return 0;
> +
> +try_remove:
> +    reply = NULL;
> +
> +    if (!remove_cmd)
> +        VIR_WARN0(_("Unable to remove network backend\n"));
> +    else if (qemudMonitorCommand(vm, remove_cmd, &reply) < 0)
> +        VIR_WARN(_("Failed to remove network backend with '%s'\n"), remove_cmd);
> +
> +    VIR_FREE(reply);
> +    VIR_FREE(remove_cmd);
> +
> +    return -1;
>  }

Should log the reply text too upon failure, since that's probably
more useful data

ACK

Regards,
Daniel
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