From 278e9478901ac272809f65a62d3b5db7d47441df Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Wed, 18 Nov 2009 15:58:32 +0000
Subject: [PATCH] Ensure driver lock is released when entering QEMU monitor

The qemudStartVMDaemon() and several functions it calls use
the QEMU monitor. The QEMU driver is locked while this function
is executing, so it is rquired to release the driver lock and
reacquire it either side of issuing a monitor command. It
failed todo so, leading to deadlock

* qemu/qemu_driver.c: Release driver when in qemudStartVMDaemon
  and things it calls
---
 src/qemu/qemu_driver.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 968118ecaa..a4a87ac683 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -118,6 +118,7 @@ static void qemudShutdownVMDaemon(virConnectPtr conn,
 static int qemudDomainGetMaxVcpus(virDomainPtr dom);
 
 static int qemuDetectVcpuPIDs(virConnectPtr conn,
+                              struct qemud_driver *driver,
                               virDomainObjPtr vm);
 
 static int qemuUpdateActivePciHostdevs(struct qemud_driver *driver,
@@ -1314,6 +1315,7 @@ qemudWaitForMonitor(virConnectPtr conn,
 
 static int
 qemuDetectVcpuPIDs(virConnectPtr conn,
+                   struct qemud_driver *driver,
                    virDomainObjPtr vm) {
     pid_t *cpupids = NULL;
     int ncpupids;
@@ -1331,12 +1333,12 @@ qemuDetectVcpuPIDs(virConnectPtr conn,
 
     /* What follows is now all KVM specific */
 
-    qemuDomainObjEnterMonitor(vm);
+    qemuDomainObjEnterMonitorWithDriver(driver, vm);
     if ((ncpupids = qemuMonitorGetCPUInfo(priv->mon, &cpupids)) < 0) {
-        qemuDomainObjExitMonitor(vm);
+        qemuDomainObjExitMonitorWithDriver(driver, vm);
         return -1;
     }
-    qemuDomainObjExitMonitor(vm);
+    qemuDomainObjExitMonitorWithDriver(driver, vm);
 
     /* Treat failure to get VCPU<->PID mapping as non-fatal */
     if (ncpupids == 0)
@@ -1357,6 +1359,7 @@ qemuDetectVcpuPIDs(virConnectPtr conn,
 
 static int
 qemudInitCpus(virConnectPtr conn,
+              struct qemud_driver *driver,
               virDomainObjPtr vm,
               const char *migrateFrom) {
 #if HAVE_SCHED_GETAFFINITY
@@ -1397,15 +1400,15 @@ qemudInitCpus(virConnectPtr conn,
     /* XXX This resume doesn't really belong here. Move it up to caller */
     if (migrateFrom == NULL) {
         /* Allow the CPUS to start executing */
-        qemuDomainObjEnterMonitor(vm);
+        qemuDomainObjEnterMonitorWithDriver(driver, vm);
         if (qemuMonitorStartCPUs(priv->mon, conn) < 0) {
             if (virGetLastError() == NULL)
                 qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                                  "%s", _("resume operation failed"));
-            qemuDomainObjExitMonitor(vm);
+            qemuDomainObjExitMonitorWithDriver(driver, vm);
             return -1;
         }
-        qemuDomainObjExitMonitor(vm);
+        qemuDomainObjExitMonitorWithDriver(driver, vm);
     }
 
     return 0;
@@ -1422,12 +1425,12 @@ qemuInitPasswords(struct qemud_driver *driver,
         vm->def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_VNC &&
         (vm->def->graphics[0]->data.vnc.passwd || driver->vncPassword)) {
 
-        qemuDomainObjEnterMonitor(vm);
+        qemuDomainObjEnterMonitorWithDriver(driver, vm);
         ret = qemuMonitorSetVNCPassword(priv->mon,
                                         vm->def->graphics[0]->data.vnc.passwd ?
                                         vm->def->graphics[0]->data.vnc.passwd :
                                         driver->vncPassword);
-        qemuDomainObjExitMonitor(vm);
+        qemuDomainObjExitMonitorWithDriver(driver, vm);
     }
 
     return ret;
@@ -2294,21 +2297,21 @@ static int qemudStartVMDaemon(virConnectPtr conn,
     if (qemudWaitForMonitor(conn, driver, vm, pos) < 0)
         goto abort;
 
-    if (qemuDetectVcpuPIDs(conn, vm) < 0)
+    if (qemuDetectVcpuPIDs(conn, driver, vm) < 0)
         goto abort;
 
-    if (qemudInitCpus(conn, vm, migrateFrom) < 0)
+    if (qemudInitCpus(conn, driver, vm, migrateFrom) < 0)
         goto abort;
 
     if (qemuInitPasswords(driver, vm) < 0)
         goto abort;
 
-    qemuDomainObjEnterMonitor(vm);
+    qemuDomainObjEnterMonitorWithDriver(driver, vm);
     if (qemuMonitorSetBalloon(priv->mon, vm->def->memory) < 0) {
-        qemuDomainObjExitMonitor(vm);
+        qemuDomainObjExitMonitorWithDriver(driver, vm);
         goto abort;
     }
-    qemuDomainObjExitMonitor(vm);
+    qemuDomainObjExitMonitorWithDriver(driver, vm);
 
     if (virDomainSaveStatus(conn, driver->stateDir, vm) < 0)
         goto abort;
-- 
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