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Make checks for inactive QEMU guest more robust

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Before issuing monitor commands it is neccessary to check whether
the guest is still running. Most places use virDomainIsActive()
correctly, but a few relied on 'priv->mon != NULL'. In theory
these should be equivalent, but the release of the last reference
count on priv->mon can be delayed a small amount of time until
the event handler is finally deregistered. A further ref counting
bug also means that priv->mon might be never released. In such a
case, code could mistakenly issue a monitor command and wait for
a response that will never arrive, effectively leaving the QEMU
driver waiting on virCondWait() forever..

To protect against these possibilities, make sure all code uses
virDomainIsActive(), not 'priv->mon != NULL'

* src/qemu/qemu_driver.c: Replace 'priv->mon != NULL' with
  calls to 'priv->mon != NULL'()
This commit is contained in:
Daniel P. Berrange 2010-06-10 15:07:21 +01:00
parent 9b0244ae38
commit 8d616decc5
1 changed files with 5 additions and 5 deletions
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10
src/qemu/qemu_driver.c
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@ -5219,7 +5219,7 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
endjob: endjob:
if (vm) { if (vm) {
if (ret != 0) { if (ret != 0) {
if (header.was_running && priv->mon) { if (header.was_running && virDomainObjIsActive(vm)) {
qemuDomainObjEnterMonitorWithDriver(driver, vm); qemuDomainObjEnterMonitorWithDriver(driver, vm);
rc = qemuMonitorStartCPUs(priv->mon, dom->conn); rc = qemuMonitorStartCPUs(priv->mon, dom->conn);
qemuDomainObjExitMonitorWithDriver(driver, vm); qemuDomainObjExitMonitorWithDriver(driver, vm);
@ -5531,7 +5531,7 @@ endjob:
/* Since the monitor is always attached to a pty for libvirt, it /* Since the monitor is always attached to a pty for libvirt, it
will support synchronous operations so we always get here after will support synchronous operations so we always get here after
the migration is complete. */ the migration is complete. */
else if (resume && paused && priv->mon) { else if (resume && paused && virDomainObjIsActive(vm)) {
qemuDomainObjEnterMonitorWithDriver(driver, vm); qemuDomainObjEnterMonitorWithDriver(driver, vm);
if (qemuMonitorStartCPUs(priv->mon, dom->conn) < 0) { if (qemuMonitorStartCPUs(priv->mon, dom->conn) < 0) {
if (virGetLastError() == NULL) if (virGetLastError() == NULL)
@ -7657,7 +7657,7 @@ cleanup:
return ret; return ret;
try_remove: try_remove:
if (!priv->mon) if (!virDomainObjIsActive(vm))
goto cleanup; goto cleanup;
if (vlan < 0) { if (vlan < 0) {
@ -7689,7 +7689,7 @@ try_remove:
goto cleanup; goto cleanup;
try_tapfd_close: try_tapfd_close:
if (!priv->mon) if (!virDomainObjIsActive(vm))
goto cleanup; goto cleanup;
if (tapfd_name) { if (tapfd_name) {
@ -10743,7 +10743,7 @@ static int doTunnelMigrate(virDomainPtr dom,
retval = doTunnelSendAll(st, client_sock); retval = doTunnelSendAll(st, client_sock);
cancel: cancel:
if (retval != 0 && priv->mon) { if (retval != 0 && virDomainObjIsActive(vm)) {
qemuDomainObjEnterMonitorWithDriver(driver, vm); qemuDomainObjEnterMonitorWithDriver(driver, vm);
qemuMonitorMigrateCancel(priv->mon); qemuMonitorMigrateCancel(priv->mon);
qemuDomainObjExitMonitorWithDriver(driver, vm); qemuDomainObjExitMonitorWithDriver(driver, vm);