[Bug runtime/6030] stap, staprun, stapio interaction quirks: stale module left unloaded

[Frank Ch. Eigler]

anithra <anithra@linux.vnet.ibm.com> writes:

> [...]  kill(SIGTERM, -stap_pid) solves the problem from the StapGUI
> point of qview. I'm able to terminate both the stap& stapio process
> and thereby unload the module.

Good.

> But the behaviour of the stap process still doesn't seem correct. If
> a signal is sent to the stap process it terminates leaving stapio
> running as a zombie and the module still loaded.

I still don't quite see how this scenario would happen.  If stapio is
a zombie, then this means that it has exited.  As a part of exiting,
stapio attempts to exec "staprun -d MODULE" to unload the module.  If
a module is left behind loaded, something other than stap process's
own signal processing must have been involved.

(By the way, there is no such thing as "running as a zombie".  Zombie
processes are unsightly but otherwise consume essentially no
resources.)

- FChE