Re: [PATCH] Fix compilation errors for itrace probe point - v2

[Maynard Johnson <maynardj at us dot ibm dot com>]

David Smith wrote:
> Maynard Johnson wrote:
> > Hello,
> > I recently pulled down the systemtap src onto a Fedora 10 system and tried to use the itrace
> > probe point.  The resulting kernel module failed to compile because
> the runtime/itrace.c file
> > had not been updated to reflect the recent utrace interface changes.
> This problem had not
> > been caught because the itrace test is currently disabled (since it
> fails on x86_64).
>
> I looked at your changes a bit.  In remove_usr_itrace_info(), you
> probably need to ignore EALREADY (which means the DEATH callback has
> already begun so there is no point in detaching).
>
> The changes look reasonable, but with a bit more effort you should be
> able to support both the original utrace interface (for systems like
> RHEL5) and the new utrace interface simultaneously.  The task_finder
> layer does this now - look for '#ifdef UTRACE_ORIG_VERSION' sections and
> look at runtime/utrace_compatibility.h.  Basically you write to the new
> interface and use the defines and wrappers in
> runtime/utrace_compatibility.h to make the original utrace interface
> look like the new interface.
>
> It is possible you might need to add additional defines to
> runtime/utrace_compatibility.h since the itrace code uses parts of
> utrace that the task_finder layer doesn't use.
>
> Let me know if you need help with this or additional information.
Thanks for the feedback.  The revised patch I'm attaching here contains two 
changes compared to the original:  it ignores EALREADY in 
remove_usr_itrace_info(); and I've added a private version of 
'access_process_vm' (as discussed on a separate posting thread).

Other issues I will continue to work on are:
	- itrace test fails on x86_64
	- add backward support for older utrace interface

Frank had granted me write access to the SystemTap repository a few months ago, 
so I can commit this when I get approval.

Thanks.
-Maynard
>