[libvirt] [PATCH] qemu_agent: report VIR_ERR_AGENT_UNSYNCED if guest_sync failed.

[Nikolay Shirokovskiy]

On 30.11.2017 06:08, Chen Hanxiao wrote:
> From: Chen Hanxiao <chenhanxiao at gmail.com>
> 
> Commit 5e5019bf removed this kind of error.
> 
> But we've already protected race condition by qemuDomainObjEnterAgent,
> it was very unlikely to revieve a sync from other calls.
> For call from virDomain*, it's better to show this error
> if we really got a mismatch sync.

Hi, Chen. 

We've observed such condition on practice. So if you report error in this
place then agent monitor will enter error state and will become unusable
and there are no means to leave this state other then restarting libvirtd
AFAIK. Even if there is a option to reset monitor then client will reset
it by itself on receiving VIR_ERR_AGENT_UNSYNCED error. But then why enter
error state in this case?

Nikolay

> 
> Signed-off-by: Chen Hanxiao <chenhanxiao at gmail.com>
> ---
>  src/qemu/qemu_agent.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/src/qemu/qemu_agent.c b/src/qemu/qemu_agent.c
> index 5d125c413..cdcacf5c8 100644
> --- a/src/qemu/qemu_agent.c
> +++ b/src/qemu/qemu_agent.c
> @@ -354,7 +354,9 @@ qemuAgentIOProcessLine(qemuAgentPtr mon,
>                  if (msg->id != id) {
>                      VIR_DEBUG("Guest agent returned ID: %llu instead of %llu",
>                                id, msg->id);
> -                    ret = 0;
> +                    virReportError(VIR_ERR_AGENT_UNSYNCED,
> +                                   _("Guest agent returned ID: %llu "
> +                                     "instead of %llu"), id, msg->id);
>                      goto cleanup;
>                  }
>              }
>