From: Jiri Denemark <jdenemar@redhat.com>
Date: Fri, 3 Dec 2010 09:48:31 +0000 (+0100)
Subject: qemu: Fix a possible deadlock in p2p migration
X-Git-Tag: v0.8.7~161
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=584c13f3560fca894c568db39b81a856db1387cb;p=thirdparty%2Flibvirt.git

qemu: Fix a possible deadlock in p2p migration

Two more calls to remote libvirtd have to be surrounded by
qemuDomainObjEnterRemoteWithDriver() and
qemuDomainObjExitRemoteWithDriver() to prevent possible deadlock between
two communicating libvirt daemons.

See commit f0c8e1cb3774d6f09e2681ca1988bf235a343007 for further details.
---

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 1b86b5e18e..f5164e1327 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -11625,24 +11625,38 @@ static int doPeer2PeerMigrate(virDomainPtr dom,
     int ret = -1;
     virConnectPtr dconn = NULL;
     char *dom_xml;
+    bool p2p;
 
     /* the order of operations is important here; we make sure the
      * destination side is completely setup before we touch the source
      */
 
+    qemuDomainObjEnterRemoteWithDriver(driver, vm);
     dconn = virConnectOpen(uri);
+    qemuDomainObjExitRemoteWithDriver(driver, vm);
     if (dconn == NULL) {
         qemuReportError(VIR_ERR_OPERATION_FAILED,
                         _("Failed to connect to remote libvirt URI %s"), uri);
         return -1;
     }
-    if (!VIR_DRV_SUPPORTS_FEATURE(dconn->driver, dconn,
-                                  VIR_DRV_FEATURE_MIGRATION_P2P)) {
+
+    qemuDomainObjEnterRemoteWithDriver(driver, vm);
+    p2p = VIR_DRV_SUPPORTS_FEATURE(dconn->driver, dconn,
+                                   VIR_DRV_FEATURE_MIGRATION_P2P);
+    qemuDomainObjExitRemoteWithDriver(driver, vm);
+    if (!p2p) {
         qemuReportError(VIR_ERR_OPERATION_FAILED, "%s",
                         _("Destination libvirt does not support peer-to-peer migration protocol"));
         goto cleanup;
     }
 
+    /* domain may have been stopped while we were talking to remote daemon */
+    if (!virDomainObjIsActive(vm)) {
+        qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                        _("guest unexpectedly quit"));
+        goto cleanup;
+    }
+
     dom_xml = qemudVMDumpXML(driver, vm,
                              VIR_DOMAIN_XML_SECURE |
                              VIR_DOMAIN_XML_UPDATE_CPU);