libvirt users - Aug 2017 - dump in virEventPollRunOnce

libvirt
version: 3.4.0
architecture: x86_64 ubuntu16.04-server

hypervisor: kvm,qemu

My program use libvirt event , the program is a module(.so) file in cloud
application, when unload the module, program will dump in virEventPoolRunOnce
call.
program frame

virInitialize
virEventAddTimeOut
virEventRunDefaultImpl
virConnectXXX
virConnectDomainEventRegisterAny
...
virConnectDomainEventDeregisterAny
...

when unload the module will dump , the gdb bt commad output is
[Thread debugging using libthread_db enabled]
Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/usr/local/lssa/bin/lssa -f'.
Program terminated with signal SIGSEGV, Segmentation fault.
---Type <return> to continue, or q <return> to quit---
#0  0x00007f9a3e9fc2f2 in ?? ()
[Current thread is 1 (Thread 0x7f9a39349700 (LWP 2897))]
(gdb) bt
#0  0x00007f9a3e9fc2f2 in ?? ()
#1  0x00007f9a3e1728bd in virEventPollRunOnce () from /usr/lib/libvirt.so.0
#2  0x00007f9a3e171391 in virEventRunDefaultImpl () from /usr/lib/libvirt.so.0
#3  0x00007f9a3e9fbc16 in ?? ()
#4  0x0000000000000000 in ?? ()
(gdb)

Thanks

On 08/21/2017 05:22 AM, llilulu wrote:
> libvirt
> version: 3.4.0
> architecture: x86_64 ubuntu16.04-server
> 
> hypervisor: kvm,qemu
> 
> My program use libvirt event , the program is a module(.so) file in cloud
application, when unload the module, program will dump in virEventPoolRunOnce
call.
> program frame
> 
This is perfectly expected. IIUC you're providing your own event loop
callbacks (virEventRegisterImpl()) which are implemented in your module.
Well, if you remove it dead pointers are left behind in libvirt's
internals and thus when libvirt tries to call your function it accesses
dead pointer and thus SIGSEGVs. The proper way to do it is to unload
your module only after the last call to libvirt (and after every
connection was closed).

Michal