[libvirt] [PATCH 3/6] qemu-driver: Enable domainMemStats in the qemu driver

[Daniel P. Berrange]

On Fri, Dec 11, 2009 at 03:26:14PM -0500, Adam Litke wrote:
> Support for memory statistics reporting is accepted for qemu inclusion.
>  
>  static int
> +qemudDomainMemoryStats (virDomainPtr dom,
> +                        struct _virDomainMemoryStat *stats,
> +                        unsigned int nr_stats)
> +{
> +    struct qemud_driver *driver = dom->conn->privateData;
> +    virDomainObjPtr vm;
> +    unsigned int nr_stats_ret = -1;
> +
> +    qemuDriverLock(driver);
> +    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
> +    qemuDriverUnlock(driver);
> +
> +    if (!vm) {
> +        char uuidstr[VIR_UUID_STRING_BUFLEN];
> +        virUUIDFormat(dom->uuid, uuidstr);
> +        qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_DOMAIN,
> +                         _("no domain with matching uuid '%s'"), uuidstr);
> +        goto cleanup;
> +    }
> +
> +    if (virDomainIsActive(vm))
> +        nr_stats_ret = qemuMonitorGetMemoryStats(vm, stats, nr_stats);

The thread locking rules require that you realize the lock on 'vm'
before invoking any monitor command and re-acquire it afterwards.
So this line of code should look like
  
        qemuDomainObjPrivatePtr priv = vm->privateData;
        qemuDomainObjEnterMonitor(vm);
        nr_stats_ret = qemuMonitorGetMemoryStats(vm, stats, nr_stats);
        qemuDomainObjExitMonitor(vm);

> +
> +cleanup:
> +    if (vm)
> +        virDomainObjUnlock(vm);
> +    return nr_stats_ret;
> +}

In this method, if the domain is not active, it returns -1, without
atually reporting what the error was. There needs to be code like

   if (!virDomainIsActive(vm)) {
      qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_INVALID,
                       "%s", _("domain is not running"));


Regards,
Daniel
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