Re: [libvirt] [PATCH] qemu: agent: Reset agentError when qemuConnectAgent success

qemuAgentClose and qemuAgentIO have race condition, as follows: main thread: second thread: virEventPollRunOnce processSerialChangedEvent virEventPollDispatchHandles virMutexUnlock(&eventLoop.lock) qemuAgentClose virObjectLock(mon) virEventRemoveHandle VIR_FORCE_CLOSE(mon->fd) virObjectUnlock(mon) priv->agentError = false qemuAgentIO virObjectLock(mon) mon->fd != fd --> error = true qemuProcessHandleAgentError priv->agentError = true virObjectUnlock(mon) virMutexLock(&eventLoop.lock) qemuAgentClose set the mon->fd to '-1', and then qemuAgentIO check the mon->fd not equals to fd that registered before. qemuProcessHandleAgentError will be called to set priv->agentError to 'true', then the priv->agentError is always 'true' except restart libvirtd or restart qemu-guest-agent process in guest. We can't send any qemu-agent-command anymore even if qemuConnectAgent return success later. This is accidently occurs when hot-add-vcpu in windows2012. virsh setvcpus ... virsh qemu-agent-command $vm '{"execute":"guest-get-vcpus"}' Reset the priv->agentError to 'false' when qemuConnectAgent sucess to fix this problem. Signed-off-by: Wang Yechao <wang.yechao255(a)zte.com.cn&gt; --- src/qemu/qemu_process.c | 1 + 1 file changed, 1 insertion(+) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 29b0ba1..4fbb955 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -269,6 +269,7 @@ qemuConnectAgent(virQEMUDriverPtr driver, virDomainObjPtr vm) virResetLastError(); } + priv->agentError = false; return 0; }