[PATCH 0/4] tracing: add ref_trace_final_put tracing

[Eugene Mavick]

When debugging use-after-free(UAF) bugs, knowing when the object reaches
0 references and enters final release can significantly aide the
debugging process.

There is currently no universal way to trace this information.

This patches traces the final puts in the most widely used refcounting
implementations, refcount_t(and thus kref which uses it), and
percpu-ref.

The tracepoint records three fields:
- caller: function that called the refcounting
  function(refcount_sub_and_test, percpu_ref_put_many)
- fn: refcounting function(eg refcount_sub_and_test)
- obj: refcount object(struct percpu_ref, refcount_t) 

Signed-off-by: Eugene Mavick <m@xxxxxxxxxx>
---
Eugene Mavick (4):
      tracing: add ref_trace_final_put tracepoint
      refcount: add ref_trace_final_put tracepoint
      percpu-refcount: add ref_trace_final_put trace
      kunit: add test for ref_trace_final_put

 MAINTAINERS                      |   3 +
 include/linux/percpu-refcount.h  |   5 +-
 include/linux/ref_trace.h        |  26 ++++++++
 include/linux/refcount.h         |   2 +
 include/trace/events/ref_trace.h |  46 +++++++++++++
 lib/Kconfig                      |  10 +++
 lib/Makefile                     |   2 +
 lib/ref_trace.c                  |  12 ++++
 lib/tests/Makefile               |   1 +
 lib/tests/ref_trace_kunit.c      | 138 +++++++++++++++++++++++++++++++++++++++
 10 files changed, 244 insertions(+), 1 deletion(-)
---
base-commit: df685633c3dbc67441cc86f1c3fee58de4652ba2
change-id: 20260624-refcount-final-put-trace-49bd7c39bd5a

Best regards,
-- 
Eugene Mavick <m@xxxxxxxxxx>