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

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2008-04-08 14:12 -------
(In reply to comment #3)
> cron wouldn't work well. If you wanted to run the same script you would
> not be able to until cron had triggered the cleanup.  As a user, I find
> stuff like that extremely annoying.

Remember, the scenario here is that the user killed his own stap*
processes with kill -9.  Such extreme annoyance is self-induced.

I recall we came across some runes that perform pseudo-renaming of a
compiled module before insmod time.  If that can be made to work
(as a part of staprun presumably), then reexecuting the same probe
several times concurrently would be possible.

Another simple possibility is for staprun to attempt to *unload* a
module with the same name that it's about to load - to clean up an
orphaned zombie.  (It'd use sys_delete_module(2) with O_NONBLOCK.)


> I still prefer the solution I described here
> http://sources.redhat.com/bugzilla/show_bug.cgi?id=5716
> 
> "I think a simpler, more secure approach would be to simply separate the
> module removal and build it as a standalone suid program.   [...]

Perhaps, but is it useful & necessary enough to overcome the natural
skepticism toward adding anything setuid?


-- 


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

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