[libvirt] [PATCH] Fix buzzilla 738778

[Daniel Veillard]

On Fri, Sep 16, 2011 at 09:03:30AM -0400, Stefan Berger wrote:
> This patch fixes the bug shown in bugzilla 738778. It's not an
> nwfilter problem but a connection sharing / closure issue.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=738778
> 
> Depending on the speed / #CPUs of the machine you are using you may
> not see this bug all the time.
> 
> Signed-off-by: Stefan Berger <stefanb at linux.vnet.ibm.com>
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index f8a8475..1991777 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -2539,6 +2539,10 @@ struct qemuProcessReconnectData {
>  /*
>   * Open an existing VM's monitor, re-detect VCPU threads
>   * and re-reserve the security labels in use
> + *
> + * We own the virConnectPtr we are passed here - whoever started
> + * this thread function has increased the reference counter to it
> + * so that we now have to close it.
>   */
>  static void
>  qemuProcessReconnect(void *opaque)
> @@ -2632,6 +2636,8 @@ qemuProcessReconnect(void *opaque)
> 
>      qemuDriverUnlock(driver);
> 
> +    virConnectClose(conn);
> +
>      return;
> 
>  error:
> @@ -2656,6 +2662,8 @@ error:
>              virDomainObjUnlock(obj);
>      }
>      qemuDriverUnlock(driver);
> +
> +    virConnectClose(conn);
>  }
> 
>  static void
> @@ -2706,7 +2714,16 @@ qemuProcessReconnectHelper(void *payload,
>      if (qemuDomainObjBeginJobWithDriver(src->driver, obj,
> QEMU_JOB_MODIFY) < 0)
>          goto error;
> 
> +    /* Since we close the connection later on, we have to make sure
> +     * that the threads we start see a valid connection throughout their
> +     * lifetime. We simply increase the reference counter here.
> +     */
> +    virConnectRef(data->conn);
> +
>      if (virThreadCreate(&thread, true, qemuProcessReconnect, data) < 0) {
> +
> +        virConnectClose(data->conn);
> +
>          qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                          _("Could not create thread. QEMU initialization "
>                            "might be incomplete"));

  That sounds like a nasty bug and hard to track !
I think this makes sense, hopefully I'm right :-)

ACK, please push !

Daniel

-- 
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