Re: [RFC PATCH] qemu: Do not report eof when processing monitor IO

On 10/8/21 11:37 PM, Jim Fehlig wrote: > There have been countless reports from users concerned about the following > error reported by libvirtd when qemu domains are shutdown > > internal error: End of file from qemu monitor > > While the error is harmless, users often mistaken it for real problem with > their deployments. EOF from the monitor can't be entirely ignored since > other threads may be using the monitor and must be able to detect the EOF > condition. > > One potential fix is to delay reporting EOF until the monitor is used > after EOF is detected. This patch adds a 'goteof' member to the > qemuMonitor structure, which is set when EOF is detected on the monitor > socket. If another thread later tries to send data on the monitor, the > EOF error is reported. > > Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; > --- > > An RFC patch to squelch qemu monitor EOF error messages on VM shutdown. > Previous discussions and information on testing of the patch can be > found in this thread > > https://listman.redhat.com/archives/libvir-list/2021-September/msg00949.html > > src/qemu/qemu_monitor.c | 29 ++++++++++++++++------------- > 1 file changed, 16 insertions(+), 13 deletions(-) > > diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c > index 5fc23f13d3..751ec8ba6c 100644 > --- a/src/qemu/qemu_monitor.c > +++ b/src/qemu/qemu_monitor.c > @@ -113,6 +113,7 @@ struct _qemuMonitor { > > /* true if qemu no longer wants 'props' sub-object of object-add */ > bool objectAddNoWrap; > + bool goteof; > }; > > /** > @@ -526,10 +527,10 @@ qemuMonitorIO(GSocket *socket G_GNUC_UNUSED, > { > qemuMonitor *mon = opaque; > bool error = false; > - bool eof = false; > bool hangup = false; > > virObjectRef(mon); > + mon->goteof = false; > At this point, the monitor object is unlocked (see the line below). So setting this flag outside is potentially dangerous. But, I don't think we need to set ->goteof here at all, do we? I mean, the moment we see EOF the monitor object will be disposed and not ever used again.