On 02/15/2018 11:43 AM, Daniel P. Berrangé wrote:
> The controller model is slightly unusual in that the default value is
> -1, not 0. As a result the default value is not covered by any of the
> existing enum cases. This in turn means that any switch() statements
> that think they have covered all cases, will in fact not match the
> default value at all. In the qemuDomainDeviceCalculatePCIConnectFlags()
> method this has caused a serious mistake where we fallthough from the
> SCSI controller case, to the VirtioSerial controller case, and from
> the USB controller case to the IDE controller case.
>
> By adding explicit enum constant starting at -1, we can ensure switches
> remember to handle the default case.
>
> Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
> ---
> src/conf/domain_addr.c | 5 +++++
> src/conf/domain_conf.c | 1 +
> src/conf/domain_conf.h | 4 ++++
> src/qemu/qemu_command.c | 17 ++++++++++++++---
> src/qemu/qemu_domain.c | 10 +++++++++-
> src/qemu/qemu_domain_address.c | 22 ++++++++++++++++++++++
> src/vbox/vbox_common.c | 13 +++++++++----
> 7 files changed, 64 insertions(+), 8 deletions(-)
>
There's a few places where in the code where model is compared against
-1 that could perhaps use the VIR_DOMAIN_CONTROLLER_MODEL_*_DEFAULT (I
used 'model.*=.*-1' in the Find this egrep pattern in cscope).
At least one of them (below) caused a Coverity complaint.
So should any of those be altered or should we just live with the fact
that using/knowing -1 is the 'default' model?
> diff --git a/src/conf/domain_addr.c b/src/conf/domain_addr.c
> index 6422682391..df19c6be1a 100644
> --- a/src/conf/domain_addr.c
> +++ b/src/conf/domain_addr.c
[...]
> @@ -1746,6 +1750,7 @@ virDomainUSBAddressControllerModelToPorts(virDomainControllerDefPtr cont)
> return cont->opts.usbopts.ports;
> return 8;
>
> + case VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT:
Coverity points out that because at the top of this function, we have:
if (model == -1)
model = VIR_DOMAIN_CONTROLLER_MODEL_USB_PIIX3_UHCI;
this particular condition cannot be met - IOW: DEADCODE
Since the code isn't changing cont->model - we could just remove the
@model local and move the DEFAULT into the return 2 leaving some sort of
comment (perhaps) that DEFAULT == PIIX3_UHCI?
> case VIR_DOMAIN_CONTROLLER_MODEL_USB_NONE:
> case VIR_DOMAIN_CONTROLLER_MODEL_USB_LAST:
> break;
[...]
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 6c73cd7bfe..2a75a169c2 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
[...]
> @@ -2771,9 +2777,14 @@ qemuBuildControllerDevStr(const virDomainDef *domainDef,
> virBufferAsprintf(&buf, ",numa_node=%d", pciopts->numaNode);
> break;
> case VIR_DOMAIN_CONTROLLER_MODEL_PCIE_ROOT:
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> + _("Unsupported PCI-E root controller"));
PCI-Express
> + goto error;
> + case VIR_DOMAIN_CONTROLLER_MODEL_PCI_DEFAULT:
> case VIR_DOMAIN_CONTROLLER_MODEL_PCI_LAST:
> - virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> - _("wrong function called"));
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("Unexpected PCI controller model %d"),
> + def->model);
> goto error;
> }
> break;
[...]
> diff --git a/src/qemu/qemu_domain_address.c b/src/qemu/qemu_domain_address.c
> index e28119e4b1..de565dbf74 100644
> --- a/src/qemu/qemu_domain_address.c
> +++ b/src/qemu/qemu_domain_address.c
> @@ -513,6 +513,16 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
>
> case VIR_DOMAIN_CONTROLLER_TYPE_USB:
> switch ((virDomainControllerModelUSB) cont->model) {
> + case VIR_DOMAIN_CONTROLLER_MODEL_USB_DEFAULT:
> + /* XXX it isn't clear that this is the right
> + * thing to do here. We probably ought to
> + * return 0, but that breaks test suite right
> + * now because we call this method before we
> + * have turned the _DEFAULT case into a
> + * specific choice
> + */
> + return pciFlags;
> +
> case VIR_DOMAIN_CONTROLLER_MODEL_USB_NEC_XHCI:
> case VIR_DOMAIN_CONTROLLER_MODEL_USB_QEMU_XHCI:
> return pcieFlags;
> @@ -540,6 +550,16 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
>
> case VIR_DOMAIN_CONTROLLER_TYPE_SCSI:
> switch ((virDomainControllerModelSCSI) cont->model) {
> + case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_DEFAULT:
> + /* XXX it isn't clear that this is the right
> + * thing to do here. We probably ought to
> + * return 0, but that breaks test suite right
> + * now because we call this method before we
> + * have turned the _DEFAULT case into a
> + * specific choice
> + */
> + return pciFlags;
> +
I think it was Laine that asked at one time about re-ordering things -
/me taking a brief look caused my head to spin ;-) and I think this is a
fine alternative (at least for now) until someone gets the gumption to
attempt to fix it.
> case VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_SCSI:
> return virtioFlags;
[...]
For what's here w/ the issue Coverity noted handled... Adding setting
the model to *_DEFAULT is an add on if it's done...
Reviewed-by: John Ferlan <jferlan@xxxxxxxxxx>
John
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