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Re: [libvirt] [PATCHv3 02/11] qemu: Move interface cmd line construction into a separate function



On 05/16/2013 08:49 AM, Michal Privoznik wrote:
> Currently, we have one huge function to construct qemu command line.
> This is very ineffective esp. if there's a fault somewhere.
> ---
>  src/qemu/qemu_command.c | 224 +++++++++++++++++++++++++-----------------------
>  1 file changed, 117 insertions(+), 107 deletions(-)
>
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 5b95c07..4c87d70 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -6405,6 +6405,117 @@ qemuBuildGraphicsCommandLine(virQEMUDriverConfigPtr cfg,
>      return 0;
>  }
>  
> +static int
> +qemuBuildInterfaceCommandLine(virCommandPtr cmd,
> +                              virQEMUDriverPtr driver,
> +                              virConnectPtr conn,
> +                              virDomainDefPtr def,
> +                              virDomainNetDefPtr net,
> +                              virQEMUCapsPtr qemuCaps,
> +                              int vlan,
> +                              int bootindex,
> +                              enum virNetDevVPortProfileOp vmop)
> +{
> +    int ret = -1;
> +    int tapfd = -1;
> +    char *nic = NULL, *host = NULL;
> +    char *tapfdName = NULL;
> +    char *vhostfdName = NULL;
> +    int actualType = virDomainNetGetActualType(net);

Wait. So it turned out you didn't even need the virQEMUDriverConfigPtr
at all? Nice!


> +
> +    if (actualType == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
> +        /* NET_TYPE_HOSTDEV devices are really hostdev devices, so
> +         * their commandlines are constructed with other hostdevs.
> +         */
> +        return 0;
> +    }
> +
> +    if (!bootindex)
> +        bootindex = net->info.bootIndex;
> +
> +    if (actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
> +        actualType == VIR_DOMAIN_NET_TYPE_BRIDGE) {
> +        tapfd = qemuNetworkIfaceConnect(def, conn, driver, net, qemuCaps);
> +        if (tapfd < 0)
> +            goto cleanup;
> +    } else if (actualType == VIR_DOMAIN_NET_TYPE_DIRECT) {
> +        tapfd = qemuPhysIfaceConnect(def, driver, net, qemuCaps, vmop);
> +        if (tapfd < 0)
> +            goto cleanup;
> +    }
> +
> +    if (actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
> +        actualType == VIR_DOMAIN_NET_TYPE_BRIDGE ||
> +        actualType == VIR_DOMAIN_NET_TYPE_ETHERNET ||
> +        actualType == VIR_DOMAIN_NET_TYPE_DIRECT) {
> +        /* Attempt to use vhost-net mode for these types of
> +           network device */
> +        int vhostfd;
> +
> +        if (qemuOpenVhostNet(def, net, qemuCaps, &vhostfd) < 0)
> +            goto cleanup;
> +        if (vhostfd >= 0) {
> +            virCommandTransferFD(cmd, vhostfd);
> +            if (virAsprintf(&vhostfdName, "%d", vhostfd) < 0) {
> +                virReportOOMError();
> +                goto cleanup;
> +            }
> +        }
> +    }
> +
> +    if (tapfd >= 0) {
> +        virCommandTransferFD(cmd, tapfd);
> +        if (virAsprintf(&tapfdName, "%d", tapfd) < 0) {
> +            virReportOOMError();
> +            goto cleanup;
> +        }
> +    }

I didn't notice this before - it's nice that you you moved this common
clause out of the BRIDGE and DIRECT cases, but why is it down below the
vhostnet handling, instead of right up with the code that created the tapfd?


> +
> +    /* Possible combinations:
> +     *
> +     *  1. Old way:   -net nic,model=e1000,vlan=1 -net tap,vlan=1
> +     *  2. Semi-new:  -device e1000,vlan=1        -net tap,vlan=1
> +     *  3. Best way:  -netdev type=tap,id=netdev1 -device e1000,id=netdev1
> +     *
> +     * NB, no support for -netdev without use of -device
> +     */
> +    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NETDEV) &&
> +        virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
> +        if (!(host = qemuBuildHostNetStr(net, driver,
> +                                         ',', vlan, tapfdName,
> +                                         vhostfdName)))
> +            goto cleanup;
> +        virCommandAddArgList(cmd, "-netdev", host, NULL);
> +    }
> +    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
> +        if (!(nic = qemuBuildNicDevStr(net, vlan, bootindex, qemuCaps)))
> +            goto cleanup;
> +        virCommandAddArgList(cmd, "-device", nic, NULL);
> +    } else {
> +        if (!(nic = qemuBuildNicStr(net, "nic,", vlan)))
> +            goto cleanup;
> +        virCommandAddArgList(cmd, "-net", nic, NULL);
> +    }
> +    if (!(virQEMUCapsGet(qemuCaps, QEMU_CAPS_NETDEV) &&
> +          virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))) {
> +        if (!(host = qemuBuildHostNetStr(net, driver,
> +                                         ',', vlan, tapfdName,
> +                                         vhostfdName)))
> +            goto cleanup;
> +        virCommandAddArgList(cmd, "-net", host, NULL);
> +    }
> +
> +    ret = 0;
> +cleanup:
> +    if (ret < 0)
> +        virDomainConfNWFilterTeardown(net);
> +    VIR_FREE(nic);
> +    VIR_FREE(host);
> +    VIR_FREE(tapfdName);
> +    VIR_FREE(vhostfdName);
> +    return ret;
> +}
> +
>  /*
>   * Constructs a argv suitable for launching qemu with config defined
>   * for a given virtual machine.
> @@ -7327,118 +7438,17 @@ qemuBuildCommandLine(virConnectPtr conn,
>  
>          for (i = 0 ; i < def->nnets ; i++) {
>              virDomainNetDefPtr net = def->nets[i];
> -            char *nic, *host;
> -            char tapfd_name[50] = "";
> -            char vhostfd_name[50] = "";
> -            int vlan;
> -            int bootindex = bootNet;
> -            int actualType = virDomainNetGetActualType(net);
> -
> -            if (actualType == VIR_DOMAIN_NET_TYPE_HOSTDEV) {
> -                /* NET_TYPE_HOSTDEV devices are really hostdev devices, so
> -                 * their commandlines are constructed with other hostdevs.
> -                 */
> -                continue;
> -            }
> -
> -            bootNet = 0;
> -            if (!bootindex)
> -                bootindex = net->info.bootIndex;
> -
> +            int vlan = i;
>              /* VLANs are not used with -netdev, so don't record them */
>              if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NETDEV) &&
>                  virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))
>                  vlan = -1;
> -            else
> -                vlan = i;
>  
> -            if (actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
> -                actualType == VIR_DOMAIN_NET_TYPE_BRIDGE) {
> -                int tapfd = qemuNetworkIfaceConnect(def, conn, driver, net,
> -                                                    qemuCaps);
> -                if (tapfd < 0)
> -                    goto error;
> -
> -                last_good_net = i;
> -                virCommandTransferFD(cmd, tapfd);
> -
> -                if (snprintf(tapfd_name, sizeof(tapfd_name), "%d",
> -                             tapfd) >= sizeof(tapfd_name))
> -                    goto no_memory;
> -            } else if (actualType == VIR_DOMAIN_NET_TYPE_DIRECT) {
> -                int tapfd = qemuPhysIfaceConnect(def, driver, net,
> -                                                 qemuCaps, vmop);
> -                if (tapfd < 0)
> -                    goto error;
> -
> -                last_good_net = i;
> -                virCommandTransferFD(cmd, tapfd);
> -
> -                if (snprintf(tapfd_name, sizeof(tapfd_name), "%d",
> -                             tapfd) >= sizeof(tapfd_name))
> -                    goto no_memory;
> -            }
> -
> -            if (actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
> -                actualType == VIR_DOMAIN_NET_TYPE_BRIDGE ||
> -                actualType == VIR_DOMAIN_NET_TYPE_ETHERNET ||
> -                actualType == VIR_DOMAIN_NET_TYPE_DIRECT) {
> -                /* Attempt to use vhost-net mode for these types of
> -                   network device */
> -                int vhostfd;
> -
> -                if (qemuOpenVhostNet(def, net, qemuCaps, &vhostfd) < 0)
> -                    goto error;
> -                if (vhostfd >= 0) {
> -                    virCommandTransferFD(cmd, vhostfd);
> -
> -                    if (snprintf(vhostfd_name, sizeof(vhostfd_name), "%d",
> -                                 vhostfd) >= sizeof(vhostfd_name))
> -                        goto no_memory;
> -                }
> -            }
> -            /* Possible combinations:
> -             *
> -             *  1. Old way:   -net nic,model=e1000,vlan=1 -net tap,vlan=1
> -             *  2. Semi-new:  -device e1000,vlan=1        -net tap,vlan=1
> -             *  3. Best way:  -netdev type=tap,id=netdev1 -device e1000,id=netdev1
> -             *
> -             * NB, no support for -netdev without use of -device
> -             */
> -            if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_NETDEV) &&
> -                virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
> -                virCommandAddArg(cmd, "-netdev");
> -                if (!(host = qemuBuildHostNetStr(net, driver,
> -                                                 ',', vlan, tapfd_name,
> -                                                 vhostfd_name)))
> -                    goto error;
> -                virCommandAddArg(cmd, host);
> -                VIR_FREE(host);
> -            }
> -            if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE)) {
> -                virCommandAddArg(cmd, "-device");
> -                nic = qemuBuildNicDevStr(net, vlan, bootindex, qemuCaps);
> -                if (!nic)
> -                    goto error;
> -                virCommandAddArg(cmd, nic);
> -                VIR_FREE(nic);
> -            } else {
> -                virCommandAddArg(cmd, "-net");
> -                if (!(nic = qemuBuildNicStr(net, "nic,", vlan)))
> -                    goto error;
> -                virCommandAddArg(cmd, nic);
> -                VIR_FREE(nic);
> -            }
> -            if (!(virQEMUCapsGet(qemuCaps, QEMU_CAPS_NETDEV) &&
> -                  virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE))) {
> -                virCommandAddArg(cmd, "-net");
> -                if (!(host = qemuBuildHostNetStr(net, driver,
> -                                                 ',', vlan, tapfd_name,
> -                                                 vhostfd_name)))
> -                    goto error;
> -                virCommandAddArg(cmd, host);
> -                VIR_FREE(host);
> -            }
> +            if (qemuBuildInterfaceCommandLine(cmd, driver, conn, def, net,
> +                                              qemuCaps, vlan, bootNet, vmop) < 0)
> +                goto error;
> +            last_good_net = i;
> +            bootNet = 0;
>          }
>      }
>  

My previous ACK stands, but I would like it even better if you made the
code movement I indicated above.


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