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

["ananth at in dot ibm dot com" <sourceware-bugzilla at sourceware dot org>]

A normal ^c to terminate a stap script induces the following signals:
sender sh signal SIGCHLD receiver stap
sender sshd signal SIGINT receiver stapio
sender sshd signal SIGINT receiver staprun
sender sshd signal SIGINT receiver stap
sender stapio signal SIGUSR2 receiver stapio
sender stapio signal SIGCHLD receiver staprun
sender staprun signal 0x20 receiver staprun
sender staprun signal SIGCHLD receiver stap
sender rm signal SIGCHLD receiver stap
sender stap signal SIGCHLD receiver bash

However, kill -9 on stap and then staprun, leads to an orphaned module
kill -9 to <stap_pid>
sender bash signal SIGKILL receiver stap
sender stap signal SIGCHLD receiver bash

then kill -9 to <staprun_pid>
sender bash signal SIGKILL receiver staprun
sender staprun signal SIGCHLD receiver init

then kill -9 to <stapio_pid>
sender bash signal SIGKILL receiver stapio
sender stapio signal SIGCHLD receiver init

The module is left unloaded. Probes from the module are unregistered though.

However, if we first do a kill -9 <stapio_pid>, things are fine:
sender bash signal SIGKILL receiver stapio
sender stapio signal SIGCHLD receiver staprun
sender staprun signal 0x20 receiver staprun
sender staprun signal SIGCHLD receiver stap
sender rm signal SIGCHLD receiver stap
sender stap signal SIGCHLD receiver bash

Similar issues are seen with a kill -SIGINT to <stap_pid> or <staprun_pid>

There needs to be a clean way of killing all three process along with module
unload when one of the processes is killed.

-- 
           Summary: stap, staprun, stapio interaction quirks: stale module
                    left unloaded
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: runtime
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: ananth at in dot ibm dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=6030

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