Running DTrace Userland probes at times terminates traced process

Shrikanth Kamath shrikanth07 at gmail.com
Fri Oct 16 05:53:02 UTC 2015


It maybe a non issue but wanted to check with the forum,

I am running the following dtrace one liner on the login process

root at bsdvm#dtrace -ln 'pid$target::*:entry' -p <pid of login>

root at bsdvm:~ # ps
 PID TT  STAT    TIME COMMAND
1820 u0  Ss   0:00.02 login [pam] (login)
...

root at bsdvm:~ # uname -a
FreeBSD bsdvm 10.2-STABLE FreeBSD 10.2-STABLE #0 r286878: Tue Aug 18
22:14:16 UTC 2015
root at releng1.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC  i386


But before it can finish listing all the probes I issue a CTRL-C and
thereby stopping dtrace. This results in terminating the login
process.

When I ran ktrace on dtrace I see it does a PT_ATTACH but since I do
not allow to run it to completion and terminate early it fails to do a
 clean PT_DETACH thereby terminating the traced process.

May not be an issue if we don't kill DTrace after it has done a PT_ATTACH...

--
Shrikanth R K


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