[PATCH] tracing/function-return-tracer: clean up task start/exitcallbacks

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote:

> Impact: use deeper tracing depth safely
> 
> Some tests showed that function return tracing needed a more deeper depth
> of function calls. But it could be unsafe to store these return addresses
> to the stack.
> So these arrays will now be allocated dynamically into task_struct of current
> only when the tracer is activated.
> 
> Typical scheme when tracer is activated:
> _ allocate a return stack for each task in global list.
> _ fork: allocate the return stack for the newly created task
> _ exit: free return stack of current
> _ idle init: same as fork
> 
> I chose a default depth of 50. I don't have anymore overruns (didn't tested for
> a long time).
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> ---
>  arch/x86/include/asm/ftrace.h      |    1 -
>  arch/x86/include/asm/thread_info.h |   29 -----------
>  arch/x86/kernel/ftrace.c           |   29 ++++++-----
>  include/linux/ftrace.h             |    5 ++
>  include/linux/sched.h              |   23 ++++-----
>  kernel/exit.c                      |    5 ++-
>  kernel/fork.c                      |    4 ++
>  kernel/sched.c                     |    3 +
>  kernel/trace/ftrace.c              |   96 +++++++++++++++++++++++++++++++++++-
>  9 files changed, 137 insertions(+), 58 deletions(-)

nice! Applied to tip/tracing/function-return-tracer and i started 
testing it as well.

I've done the small cleanup below on top of your patch - we try to 
avoid #ifdefs in core kernel code as much as possible, by hiding 
.config details into include files.

	Ingo

-------------->