On 11/18/2009 11:00 AM, Daniel P. Berrange wrote:
> 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 files changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 968118e..a4a87ac 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;
ACK, fixes the qemu:///session VM startup deadlock I was seeing. Thanks!
- Cole
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