[DTrace-devel] test time-out signal

[Eugene Loh]

We create uprobes and kprobes for some providers (dtrace and fbt) and 
try to clean these probes up when we finish, even if a job was 
terminated with Ctrl-C.  There turn out to be some limitations on this, 
and if you run the test suite you'll find lots of orphaned uprobes and 
kprobes.  I think I understand the basic issues and am addressing them.

There aren't too many things going on, really.  One of them is that the 
dtrace tool sets a signal handler for SIGINT and SIGTERM.  So if you 
Ctrl-C dtrace, it captures the signal, sets a flag (g_intr++), and 
proceeds with an orderly shutdown, including cleaning up uprobes and 
kprobes.  However, if the test suite runs and a test times out, then 
"timeout --signal=KILL" sends a signal that is not captured.  The job is 
killed abruptly, and probes are *NOT* cleaned up.

How should this problem be addressed?
*)  Just let the uprobes and kprobes accumulate?
*)  Have the test suite clean the probes up?
*)  Have dtrace capture KILL the same way it captures INT and TERM?
*)  Have the test suite timeout tests with INT or TERM rather than KILL?

I would suggest a choice if one of them felt much better than the others.