[libvirt] [PATCH 4/5] qemu: Implement virDomainDetachDeviceAlias

[Peter Krempa]

On Mon, May 21, 2018 at 18:08:01 +0200, Michal Privoznik wrote:
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  src/qemu/qemu_driver.c | 41 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 0e0c0ce53e..fee152d202 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -8808,6 +8808,46 @@ qemuDomainDetachDeviceFlags(virDomainPtr dom,
>      return ret;
>  }
>  
> +
> +static int
> +qemuDomainDetachDeviceAlias(virDomainPtr dom,
> +                            const char *alias,
> +                            unsigned int flags)
> +{
> +    virQEMUDriverPtr driver = dom->conn->privateData;
> +    virDomainObjPtr vm = NULL;
> +    virDomainDeviceDef dev;
> +    int ret = -1;
> +
> +    if (!(vm = qemuDomObjFromDomain(dom)))
> +        goto cleanup;
> +
> +    if (virDomainDetachDeviceAliasEnsureACL(dom->conn, vm->def, flags) < 0)
> +        goto cleanup;
> +
> +    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
> +        goto cleanup;
> +
> +    if (virDomainDefFindDevice(vm->def, alias, &dev, true) < 0)
> +        goto endjob;

This reports an 'internal error' if the alias is not found which is not
great to present to users.

Additionally this does not deal with the active/inactive flag which is
wrong since you e.g. can't properly use this if you have a different
persistent configuration (which uses user-aliases). In that case you
can't refer to a alias in that configuration, since only vm->def is
inspected.

> +
> +    if (virDomainObjUpdateModificationImpact(vm, &flags) < 0)
> +        goto endjob;
> +
> +    if (qemuDomainDetachDeviceLiveAndConfig(driver, vm, &dev, flags) < 0)
> +        goto endjob;

Since you pass in 'dev' containing a device definition which gets freed
by this function it may become tricky. At least you will need to
document that this is happening in this function.

Note that I did not inspect all the functions called by
qemuDomainDetachDeviceLiveAndConfig to ensure that there isn't an actual
problem.

> +
> +    ret = 0;
> +
> + endjob:
> +    qemuDomainObjEndJob(driver, vm);
> +
> + cleanup:
> +    virDomainObjEndAPI(&vm);
> +    return ret;
> +}
> +
> +
>  static int qemuDomainDetachDevice(virDomainPtr dom, const char *xml)
>  {
>      return qemuDomainDetachDeviceFlags(dom, xml,
> @@ -21303,6 +21343,7 @@ static virHypervisorDriver qemuHypervisorDriver = {
>      .domainDetachDevice = qemuDomainDetachDevice, /* 0.5.0 */
>      .domainDetachDeviceFlags = qemuDomainDetachDeviceFlags, /* 0.7.7 */
>      .domainUpdateDeviceFlags = qemuDomainUpdateDeviceFlags, /* 0.8.0 */
> +    .domainDetachDeviceAlias = qemuDomainDetachDeviceAlias, /* 4.4.0 */
>      .domainGetAutostart = qemuDomainGetAutostart, /* 0.2.1 */
>      .domainSetAutostart = qemuDomainSetAutostart, /* 0.2.1 */
>      .domainGetSchedulerType = qemuDomainGetSchedulerType, /* 0.7.0 */
> -- 
> 2.16.1
> 
> --
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