Re: [Ksummit-2008-discuss] DTrace

["Frank Ch. Eigler" <fche at redhat dot com>]

Hi -

On Sat, Jul 05, 2008 at 12:05:36PM +0200, Christoph Hellwig wrote:
> > Also, it would be really great if you could write probes in regular C,
> > some pseudo C language just messes up my mind.
> 
> You can write probes in plain C, in fact I do this all the time.  what's
> missing is a nice and easy to use channel to get the traces to userspace
> and interpret them, and helper for poking at kernel data structures.

Perhaps something like like this:


probe kernel.function("foobar") // or kernel.statement("*@dir/file.c:222")
{
    probe_me_harder ($var1, $ptr->field)
}

%{
#include "linux/something.h"
%}
function probe_me_harder (v1, f1) 
%{
   struct something *s = (struct something*) THIS->v1;
   struct something_else *w = (struct something_else*) THIS->f1;
   call_some_safe_kernel_function__be_careful_out_there (s, w);
   _stp_printf ("I did something fun with %p and %p\n", s, w);
%}


# stap -g probe.stp
I did something fun with 0xdick and 0xjane.
^C


- FChE