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.
Regards,
Daniel