[Bug testsuite/13158] New: rename_module.exp leaving module behind

[Bug testsuite/13158] New: rename_module.exp leaving module behind

[dsmith at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13158

             Bug #: 13158
           Summary: rename_module.exp leaving module behind
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: testsuite
        AssignedTo: systemtap@sourceware.org
        ReportedBy: dsmith@redhat.com
    Classification: Unclassified


After the rename_module.exp testcase is run, it leaves a module behind:

------------------
# lsmod | fgrep stap
# make installcheck RUNTESTFLAGS='systemtap.base/rename_module.exp'

... stuff deleted ...

Host: Linux kvm-f15-64-1.usersys.redhat.com 2.6.40.3-0.fc15.x86_64.debug #1 SMP
Tue Aug 16 04:04:00 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
Snapshot: version 1.7/0.152 commit release-1.6-171-gd354062 + changes
GCC: 4.6.0 [gcc (GCC) 4.6.0 20110603 (Red Hat 4.6.0-10)]
Distro: Fedora release 15 (Lovelock)

Running systemtap/src/testsuite/systemtap.base/rename_module.exp ...

        === systemtap Summary ===

# of expected passes        3

... stuff deleted ...

# lsmod | fgrep stap
stap_951b7d48fc8a19bff19415442ed9be4b_677    34009  0 
------------------

This happens every time I run this test.  The problem appears to be the 2nd
test in the testcase.  Note that no staprun/stapio processes are left behind,
just the module itself.

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[Bug testsuite/13158] rename_module.exp leaving module behind

[mjw at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13158

Mark Wielaard <mjw at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mjw at redhat dot com

--- Comment #1 from Mark Wielaard <mjw at redhat dot com> 2011-09-07 11:26:05 UTC ---
It is the second test. I get the same (even when commenting out the first and
third test). But I am unable to replicate it outside the test harness.

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[Bug testsuite/13158] rename_module.exp leaving module behind

[dsmith at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13158

--- Comment #2 from David Smith <dsmith at redhat dot com> 2011-09-07 13:43:35 UTC ---
(In reply to comment #1)
> It is the second test. I get the same (even when commenting out the first and
> third test). But I am unable to replicate it outside the test harness.

I've improved the test case, making it more robust, but I think as written it
has discovered a real problem.

I finally got a reproducer outside the test harness:

# lsmod | fgrep stap
# staprun ~/.systemtap/cache/c2/stap_c216255bba9c8e0942596f8aa9732125_677.ko &
\
> killall staprun; killall stapio
[1] 20214
stapio: no process found
[1]+  Terminated              staprun
~/.systemtap/cach/c2/stap_c216255bba9c8e0942596f8aa9732125_677.ko
# lsmod | fgrep stap
stap_c216255bba9c8e0942596f8aa9732125_677    34009  0

It appears that if you kill staprun/stapio before the module has a chance to
print (the script was a simple "probe begin { printf("hello\n") }'), this bug
can happen.

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[Bug testsuite/13158] rename_module.exp leaving module behind

[dsmith at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13158

--- Comment #3 from David Smith <dsmith at redhat dot com> 2011-09-07 17:39:38 UTC ---
Here's what I believe is happening here.  The 'staprun' executable is getting
killed after it loads the module but before it exec's 'stapio'.  Since
'staprun' doesn't handle SIGINT/SIGTERM, the module remains after staprun
exits.

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[Bug testsuite/13158] rename_module.exp leaving module behind

[dsmith at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13158

David Smith <dsmith at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #4 from David Smith <dsmith at redhat dot com> 2011-10-19 15:02:58 UTC ---
Fixed in commit cedf63f by adding a SIGINT/SIGTERM/SIGHUP/SIGQUIT handler to
staprun that removes the module if this staprun had loaded the module.

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