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[Bug tapsets/6525] need utrace task-finder-based pid->execname, pid->cwd-path-name tables
- From: "wenji dot huang at oracle dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 3 Mar 2009 04:29:00 -0000
- Subject: [Bug tapsets/6525] need utrace task-finder-based pid->execname, pid->cwd-path-name tables
- References: <20080516134833.6525.fche@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From wenji dot huang at oracle dot com 2009-03-03 04:29 -------
(In reply to comment #6)
> > But it can't return the execname of most running processes like init, mingetty,
> > kjournald because the callback is never invoked.
> > Only works fine on my forked test process. My box is 2.6.27.9-159.fc10.i686.
>
> The task_finder will never be able to return the execname or pathname of kernel
> threads, like 'init' or 'kjournald'. The 'u' in 'utrace' stands for 'user' - it
> only works on user threads. I'm unsure of why 'mingetty' couldn't be found.
>
> > Did I miss something or misunderstand the mechanism?
>
> Besides the above problem of returning the execname/pathname for kernel threads,
> there are other things that won't work well in the code you posted. As
> currently written, the task_finder isn't designed to register new targets while
> running (since there is no locking provided) or to be started/stopped more than
> once.
>
Thank you for letting me know this. Seems task_finder is not good candidate
for pid lookup functions. Maybe my patch in #4 is a choice.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=6525
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