Re: [libvirt] [PATCH] do not send monitor command after monitor met error

If the monitor met a error, and we will call qemuProcessHandleMonitorEOF(). But we may try to send monitor command after qemuProcessHandleMonitorEOF() returned. Then libvirtd will be blocked in qemuMonitorSend(). Steps to reproduce this bug: 1. use gdb to attach libvirtd, and set a breakpoint in the function qemuConnectMonitor() 2. start a vm 3. let the libvirtd to run until qemuMonitorOpen() returns. 4. kill the qemu process 5. continue running libvirtd Signed-off-by: Wen Congyang <wency(a)cn.fujitsu.com&gt; --- src/qemu/qemu_monitor.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c index 800f744..eed83f4 100644 --- a/src/qemu/qemu_monitor.c +++ b/src/qemu/qemu_monitor.c @@ -572,6 +572,13 @@ qemuMonitorIO(int watch, int fd, int events, void *opaque) { mon->msg->lastErrno = EIO; virCondSignal(&mon->notify); } + /* If qemu quited unexpectedly, and we may try to send monitor + * command later. But we have no chance to wake up it. So set + * mon->lastErrno to EIO, and check it before sending monitor + * command. + */ + if (!mon->lastErrno) + mon->lastErrno = EIO; quit = 1; } else if (events) { VIR_ERROR(_("unhandled fd event %d for monitor fd %d"),

@@ -725,6 +732,12 @@ int qemuMonitorSend(qemuMonitorPtr mon, { int ret = -1; + /* Check whether qemu quited unexpectedly */ + if (mon->lastErrno) { + msg->lastErrno = mon->lastErrno; + return -1; + } + mon->msg = msg; qemuMonitorUpdateWatch(mon);