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

[John Ferlan]

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);
 }


John