[libvirt] [PATCH v2] qemu_agent: Ignore expected EOFs

[Peter Krempa]

On 01/22/13 15:11, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=892079
>
> One of my previous patches (f2a4e5f176c408) tried to fix crashing
> libvirtd on domain detroy. However, we need to copy pattern from
> qemuProcessHandleMonitorEOF() instead of decrementing reference
> counter. The rationale for this is, if qemu process is dying due
> to domain being destroyed, we obtain EOF on both the monitor and
> agent sockets. However, if the exit is expected, qemuProcessStop
> is called, which cleans both agent and monitor sockets up. We
> want qemuAgentClose() to be called iff the EOF is not expected,
> so we don't leak an FD and memory.
> ---
>
> diff to v1:
> -handle race with qemuProcessHandleMonitorEOF correctly
>
>   src/qemu/qemu_process.c | 20 ++++++++++++++++++--
>   1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 2f08215..013b2ca 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -133,14 +133,30 @@ qemuProcessHandleAgentEOF(qemuAgentPtr agent,
>       virObjectLock(vm);
>
>       priv = vm->privateData;
> -    if (priv->agent == agent &&
> -        !virObjectUnref(priv->agent))
> +
> +    if (!priv->agent) {
> +        VIR_DEBUG("Agent freed already");
> +        goto unlock;
> +    }

You shouls add to the commit message why this condition is needed.

> +
> +    if (priv->beingDestroyed) {
> +        VIR_DEBUG("Domain is being destroyed, agent EOF is expected");
> +        goto unlock;
> +    }
> +
> +    if (priv->agent == agent)
>           priv->agent = NULL;

Is there a possibility for the agent to be different from the saved one 
here?

>
>       virObjectUnlock(vm);
>       qemuDriverUnlock(driver);
>
>       qemuAgentClose(agent);
> +    return;
> +
> +unlock:
> +    virObjectUnlock(vm);
> +    qemuDriverUnlock(driver);
> +    return;
>   }

ACK with the commit message amended and the question answered.

Peter