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h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=cBoaakX6zBs/gj7AiDhBmuJ67OOemsvukMx0aYqxBDA=; b=O07omYD/TKlY63qs5PoW+4ZZDTwT++VB+WIsmTm3OoxI5CHDTxH+/38tsULm3OLJo7rPRT Fd6C2ctmmJbNp9OwmPmp2RhwO6irb62yallXsFSvv8eQ0cbWpvWMWnWYrpV7KHj4SQrlqz 3KU5ievSD16OPQOYw+IkA8Nm+D19guSXZBJ40LlRbNZi+sjVF1y/qs1sRL/EqOxT8LpDe/ DHEcMor8Zegp7VTwGHY0BSepw5ZjG6TGyRK7Ag+rh5AOeaTKLLBtbJCtH87pC9WH8hdhEp i1PFhnjbk9Mr34S/7oVIBfhyjiq4PUcJZmDhIg19hSxqxMKvmj8NO07iqlDtog== From: Eugene Mavick Subject: [PATCH v4 0/5] tracing: add ref_trace_final_put tracing Date: Sat, 01 Aug 2026 18:59:40 +0800 Message-Id: <20260801-refcount-final-put-trace-v4-0-2e58678f0ffd@mavick.dev> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAJzRbWoC/53QzWrDMAwH8FcpPs9F/oid7LT3GD0olryadklxU rNR8u5z2h26Swe9CP7C/knoIibOiSfxurmIzCVNaRxqsC8bEfY4fLBMVLPQoB04bWXmGMbzMMu YBjzK03mWc8bA0nY9+WBqbVDU76f6Mn1d6fddzfs0zWP+vk4qau3eUA8P0KIkyN623jpCFbV/+ 8SSwmFLXNYhv0LzjxCIAJR12mH3nIBWkYkE3LonBUDujGPqfQP3wnqbYu7uodQDyVTJeRvaCIa 6+GeX3bIsP6HZLKnRAQAA X-Change-ID: 20260624-refcount-final-put-trace-49bd7c39bd5a To: Will Deacon , Peter Zijlstra , Boqun Feng , Mark Rutland , Gary Guo , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, Eugene Mavick X-Developer-Signature: v=1; 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There is currently no universal way to trace this information. This patch series implements tracing of 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) - ip: return address of the trace wrapper macro call - obj: refcount object(struct percpu_ref, refcount_t) Signed-off-by: Eugene Mavick --- Changes in v4: ref-trace: -remove fn -add ip variable -change trace wrapper macro respectively, _THIS_IP_ is used for ip variable -change relevant code respect to fn removal and ip addition -fix style issues in include/linux/ref_trace.h -add new macro do_trace_ref_final_put_cond that only calls tracepoint if cond is true lib/refcount.c: -change from do_trace_ref_final_put to *_cond -remove if statement above since _cond already performs the check KUnit: -change relevant code respect to fn removal and ip addition -check if caller and ip are valid addresses -change timeout from 10 jiffies to 10 seconds -move didn't timeout assertion from before to after probe unregistration, to prevent it from impacting next test Changes in v3: include/trace/events/ref_trace.h kernel doc comments: -caller of refcount function -> return address of refcount function -ref_trace_final_put->do_ref_trace_final_put lib/ref_trace.c: add include trace/events/ref_trace.h kunit: -change Kconfig depends from FTRACE->TRACEPOINTS -EXPECT_FALSE->ASSERT_FALSE for calling percpu_ref_init -add tracepoint_synchronise_unregister to test_exit macro -added timeout to capture.count waiting -remove noinline and __always_inline from function attributes (added for testing, but accidentally submitted) -add period to the end of Kconfig help text v2 link: https://lore.kernel.org/all/20260710-refcount-final-put-trace-v2-0-557cfce860a2@mavick.dev/ Changes in v2: -include/linux/ref_trace.h: change macro name, use direct tracepoint call in macro to avoid double check -add tracepoint to refcount_dec_if_one -kunit: make significant improvements to design, fix critical bug, add test case for refcount_dec_if_one() -Link to v1: https://lore.kernel.org/r/20260705-refcount-final-put-trace-v1-0-0ae936edb750@mavick.dev --- Eugene Mavick (5): 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: add entries for ref_trace_final_put MAINTAINERS | 3 + include/linux/percpu-refcount.h | 5 +- include/linux/ref_trace.h | 40 +++++++++++ include/linux/refcount.h | 2 + include/trace/events/ref_trace.h | 51 ++++++++++++++ lib/Kconfig | 10 +++ lib/Makefile | 2 + lib/ref_trace.c | 13 ++++ lib/refcount.c | 6 +- lib/tests/Makefile | 1 + lib/tests/ref_trace_kunit.c | 141 +++++++++++++++++++++++++++++++++++++++ 11 files changed, 272 insertions(+), 2 deletions(-) --- base-commit: df685633c3dbc67441cc86f1c3fee58de4652ba2 change-id: 20260624-refcount-final-put-trace-49bd7c39bd5a Best regards, -- Eugene Mavick