Re: [libvirt] [PATCH v2 2/2] remote: free client all event callbacks at remoteClientCloseFunc

在 2017/11/12 22:45, John Ferlan 写道: > > On 11/11/2017 03:20 AM, xinhua.Cao wrote: >> >> 在 2017/11/11 5:43, John Ferlan 写道: >>> On 11/06/2017 12:47 AM, xinhua.Cao wrote: >>>> base on commit fe8f1c8b8650c8ab5e7d27338f4538582651bd14, we solve >>>> libvirt coredump problem, but it introduce a memory leak sense: >>>> >>>> 1. one client register a domain event such as reboot event >>>> 2. and client was terminated unexpectly, such as kill -9, >>> unexpectedly >>> >>>> then this client object will not free at libvirtd service program. >>>> >>>> remoteDispatchConnectDomainEventCallbackRegisterAny reference the >>>> client, >>>> but when client was terminated before it call deRegisterAny,the >>>> reference >>>> of client will not reduced to zero. so the memory leak take place. >>> What's the difference between the path that would terminate normally and >>> the one that terminates abnormally. It seems to me there might be (an) >>> extra Ref(s) on the client which prevents virNetServerClientDispose from >>> calling it's @privateDataFreeFunc which would call remoteClientFreeFunc >>> since remoteClientInitHook worked properly. >>> >>> That's what needs to be found. >> If client terminate normally, client would call >> virConnectDomainEventDeregisterAny to >> clear eventCallbacks. Then libvirt daemon will call >> remoteDispatchConnectDomainEventDeregisterAny >> -> remoteEventCallbackFree -> virObjectUnref(callback->client) to free >> eventCallbacks and unRef client. >> just think if client don't call  virConnectDomainEventDeregisterAny and >> be killed. then there is no way to call call >> remoteDispatchConnectDomainEventDeregisterAny -> remoteEventCallbackFree >> -> virObjectUnref(callback->client) >> so client's ref can't down to zero. so remoteClientFreeFunc can't be >> called. then client object memory leak. > So the client/sample code is not calling Deregister because it has no > "handling" of an abnormal exit. That is no signal handler to call > Deregister in the event some outside force kills the client/sample code > while it's processing. > > So a different solution would be to add signal handling to the code in > order to handle the kill and make the Deregister (and close) calls. signal handler can handle such as kill -15 signal, But can't handle kill -9 signal. so we also need to resolve it in libvirt