RE: udp.sendmsg

[<webman@manfbraun.de>]

Hello !

Thanks for this good information!
I just removed this code snippet and only use "execname()"
and the error went away!

I am new to Linux and it is really very hard for me ;-)
But I was able to use SystemTap to track some Virtualbox
calls, just to show them, what brings to whole server
to stop (!!) - but they are not interested .... and now,
I am trying to avoid Virtualbox like the devil the
holy water ;-)

So, this is the same machine and was my new delay ....

Best regards,
Manfred

BTW: I am of that type, that will not use "--skip-badvars",
at least, in a permanent running script ;-)

> -----Original Message-----
> From: systemtap-owner@sourceware.org [mailto:systemtap-
> owner@sourceware.org] On Behalf Of David Smith
> Sent: Thursday, August 25, 2016 9:52 PM
> To: webman@manfbraun.de; 'Frank Ch. Eigler'
> Cc: systemtap@sourceware.org
> Subject: Re: udp.sendmsg
> 
> On 08/25/2016 11:18 AM, webman@manfbraun.de wrote:
> > Hello !
> >
> > Many thanks for your answer!
> > Sometimes, writing "it's not working" reactivates some areas
> > in the own brain, do dig deeper ...
> > What ist failing for me, is my modified version of the original
> > script. I run the original and no errors at all ... ;-)
> >
> > So, here is MY version - with my little newbies thinking about
> > this type of scripts ;-)
> >
> > =======================
> > probe begin { printf("Monitoring use of port 53\n") }
> > probe end { printf("Stopped.\n") }
> >
> > probe udp.sendmsg {
> >         if ( dport == 53 ) {
> >                 task = pid2task(pid());
> >                 printf(
> >                         "UDP53 %5d.%6d %15s %d(%s/%s) %d(%s)\n",
> >                         gettimeofday_s(),
> >                         gettimeofday_ms(),
> >                         daddr,
> >                         pid(),
> >                         task_execname(task),
> >                         execname(),
> >                         ppid(),
> >                         pexecname()
> >                         )
> >         }
> > }
> 
> OK, here's a couple of things about your script.
> 
>   task = pid2task(pid())
> 
> is the same thing as:
> 
>   task = task_current()
> 
> Plus, since task is the current task, task_execname(task) and execname()
> are always going to return the same string.
> 
> So, at that point you really don't need your 'task' variable.
> 
> If you are still getting that kernel_string copy fault error, you'll
> need to delete/replace one function call at a time so that we can narrow
> down which function is causing the fault.
> 
> --
> David Smith
> dsmith@redhat.com
> Red Hat
> http://www.redhat.com
> 256.217.0141 (direct)
> 256.837.0057 (fax)