On Wed, Jan 26, 2011 at 09:46:52AM +0800, Wen Congyang wrote: > At 01/26/2011 01:02 AM, Daniel P. Berrange Write: > > On Tue, Jan 25, 2011 at 02:57:34PM +0800, Wen Congyang wrote: > >> When we kill the qemu, the function qemuMonitorSetCapabilities() > >> failed and then we close monitor. > >> > >> In another thread, mon->fd is broken and the function > >> qemuHandleMonitorEOF() is called. The function qemuHandleMonitorEOF() calls > >> qemudShutdownVMDaemon() to shutdown vm. The monitor will be > >> closed in the function qemudShutdownVMDaemon(). > >> > >> The monitor close twice and the reference is decreased to 0 unexpectedly. > >> The memory will be freed when reference is decreased to 0. > >> > >> We will remove the watch of mon->fd when the monitor is closed. This > >> request will be done in the function qemuMonitorUnwatch() in the qemuloop > >> thread. In the function qemuMonitorUnwatch(), we will lock monitor, but > >> the lock is destroyed and we will block here, > >> > >> In the main thread, we may add some watch or timeout, and will be blocked > >> because the lock of eventLoop is hold by qemuLoop thread. > >> > >> We should close monitor only once. > > > > I think the problem actually lies in the qemuConnectMonitor() > > call. This method calls qemuMonitorSetCapabilities() and > > if that fails it calls qemuMonitorClose(). > > > > The caller of qemuConnectMonitor() will see the error > > code and also try to kill the QEMU process, by calling > > qemuShutdownVMDaemon(), which calls qemuMonitorClose() > > again. > > > > So I think we need to remove the call to qemuMonitorClose() > > from qemuConnectMonitor() and just let the calls cleanup > > up via normal VM shutdown procedure. > > The function qemudWaitForMonitor() calls qemuConnectMonitor(), > but it does not shutdown VM if qemuConnectMonitor() failed.
You need to look further up the call chain. If the call to qemuMonitorSetCapabilities() fails, qemuConnectMOnitor() returns -1. If qemuConnectMonitor() returns -1, then qemuWaitForMonitor() also returns -1. If qemuWaitForMonitor returns -1, then qemudStartVMDaemon will call qemudShutdownVMDaemon which kills the guest and closes the monitor. So, by having qemuConnectMonitor() close the monitor when SetCapabilities() fails, AFAICT, we get a double-close. Regards, Daniel -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
