Backward compatibility for insn probe point

[Roland McGrath]

> I poked around the kernel source some more, but couldn't see what was
> going wrong.  

I figured you'd use some stap probes to follow the code paths!

> I've changed the itrace code to stop the task after each step trap (so
> that it acts more like ptrace).  I've tested this on several kernels
> (2.6.18-141.el5/ppc, 2.6.18-128.1.10.el5/x86_64/i686, and
> 2.6.25-14.fc9.ppc64) and it seems to work correctly.
> 
> Does this seem like a reasonable work-around?  Could there be problems
> with this approach?

I presume it kills performance.  But what works works, that's a what a
work-around is.  I'd hope that you don't make it use this "not really
right" mode for kernels with the modern utrace interface that doesn't have
this bug.


Thanks,
Roland