Description of problem:
guest job locked after OpenGraphics fail because qemu have been killed

Version-Release number of selected component (if applicable):
libvirt-1.2.16-1.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. prepare a small c progrem
# cat libvirt-test-openGraphic.c
#include <stdio.h>
#include "libvirt/libvirt.h"

int main() {
    virDomainPtr dom = NULL;
    virConnectPtr conn = NULL;
    int ret = -1;

    if (!(conn = virConnectOpen("qemu:///system")))
        return ret;

    dom = virDomainLookupByName(conn, "test3");

    ret = virDomainOpenGraphicsFD(dom, 0, 0);
 cleanup:
    virConnectClose(conn);
    return ret;
}

# gcc libvirt-test-openGraphic.c -lvirt -o libvirt-test-openGraphic.o

2. open another terminal to attach libvirtd and set breakpoint at qemuDomainOpenGraphicsFD:

(gdb) br qemuDomainOpenGraphicsFD
Breakpoint 1 at 0x7feca8b25590: file qemu/qemu_driver.c, line 17595.
(gdb) c
Continuing.
[Switching to Thread 0x7fecb208f700 (LWP 3234)]


3. call  qemuDomainOpenGraphicsFD function via c progrem:
# ./libvirt-test-openGraphic.o

4. kill the qemu when the libvirtd in this step:

17647	    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
(gdb) 
17649	    qemuDomainObjEnterMonitor(driver, vm);
(gdb) 
17650	    ret = qemuMonitorOpenGraphics(priv->mon, protocol, pair[1], "graphicsfd",                            <-------kill qemu then continue
(gdb) n
17652	    if (qemuDomainObjExitMonitor(driver, vm) < 0) {
(gdb) 
17650	    ret = qemuMonitorOpenGraphics(priv->mon, protocol, pair[1], "graphicsfd",
(gdb) 
17652	    if (qemuDomainObjExitMonitor(driver, vm) < 0) {
(gdb) 
[Thread 0x7feca73d7700 (LWP 18028) exited]

5. restart guest:

# virsh start test3
error: Failed to start domain test3
error: Timed out during operation: cannot acquire state change lock (held by remoteDispatchDomainOpenGraphicsFd)


Actual results:
guest job locked after OpenGraphics fail because qemu have been killed

Expected results:
I used gdb to reproduce this issue as we have some bugs like this(qemu crash when libvirtd enter the monitor), so it will be a possible issue in the future.

Additional info:

This upstream patch will fix this issue:

commit 91c9e4d92099dab178de9f204f0fdb91028f071a
Author: Luyao Huang <lhuang>
Date:   Tue Jun 30 11:35:13 2015 +0800

    qemu: End job even if exiting monitor after OpenGraphics(FD) fails

v1.2.17-rc2-3-g91c9e4d