[libvirt] [PATCH] qemu: Don't fail qemuProcessAttach for IOThreads if no JSON

[Daniel P. Berrange]

On Thu, Sep 18, 2014 at 06:18:22AM -0400, John Ferlan wrote:
> 
> 
> On 09/18/2014 04:39 AM, Daniel P. Berrange wrote:
> > On Wed, Sep 17, 2014 at 03:07:47PM -0400, John Ferlan wrote:
> >> While doing some investigation for another bug I found that I could
> >> not qemu-attach to the process and got the following:
> >>
> >>    error: Operation not supported: JSON monitor is required
> >>
> >> while running thru qemuProcessAttach. Since we can only get the data
> >> using the JSON parser and if the guest to be attached to doesn't have
> >> it we shouldn't just fail. See example in virsh qemu-attach for sample
> >> command that failed.
> > 
> > It isn't simply qemu-attach that's affected. If you merely try to
> > start a guest normally with a QEMU that predates JSON support this
> > would fail too.
> > 
> >> Signed-off-by: John Ferlan <jferlan at redhat.com>
> >> ---
> >>
> >> I also considered removing the call from qemuProcessAttach rather than
> >> this approach.
> >>
> >>  src/qemu/qemu_monitor.c | 8 +++-----
> >>  1 file changed, 3 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> >> index 8927dbb..4342088 100644
> >> --- a/src/qemu/qemu_monitor.c
> >> +++ b/src/qemu/qemu_monitor.c
> >> @@ -4112,11 +4112,9 @@ qemuMonitorGetIOThreads(qemuMonitorPtr mon,
> >>          return -1;
> >>      }
> >>  
> >> -    if (!mon->json) {
> >> -        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
> >> -                       _("JSON monitor is required"));
> >> -        return -1;
> >> -    }
> >> +    /* Requires JSON to make the query */
> >> +    if (!mon->json)
> >> +        return 0;
> > 
> > I think you need should do '*iothreads = NULL' for safety too.
> > 
> 
> OK with the following squashed in?
> 
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index 4342088..10f51c5 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -4113,8 +4113,10 @@ qemuMonitorGetIOThreads(qemuMonitorPtr mon,
>      }
> 
>      /* Requires JSON to make the query */
> -    if (!mon->json)
> +    if (!mon->json) {
> +        *iothreads = NULL;
>          return 0;
> +    }
> 
>      return qemuMonitorJSONGetIOThreads(mon, iothreads);
>  }

ACK

Regards,
Daniel
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