From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-101.mailbox.org (mout-p-101.mailbox.org [80.241.56.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 412A2286D70; Sat, 11 Jul 2026 04:41:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.151 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783744870; cv=none; b=ibHjaoFIIEOzzgDLd+8gjYdRaBCnt7pxBIZQP5U4S4Tpz+tSGZSBDM83lAtDIc60J5U4gZepMlTrdkifKNODECjwPKUByCM2Mx963Xlvak+YW8BotiSUBV1sTF0CyePfBj+iMPVNYjMSY9rBJDxj3j3bGgyEFfcCqSrr/kilvvA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783744870; c=relaxed/simple; bh=togALykcuUOAaOKZnU5+keMWktwavqkGC+6SZdVlIpU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=WOS9LrahBEKY/aUvmGq7mx5NrNQ/gw7cfeHC+H4sVHgRBjgpqaY+vqLhjTKG0kvYQmFA1vZkWnSiM8PoRo9UH3VFbspLaPpcObuRbSbNPfEdm1b6G+cfVJC6gxC6x9MckjaQ6Q0UTty/PkMfCEipxRTFnh81viSbYxYuPgSH408= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mavick.dev; spf=pass smtp.mailfrom=mavick.dev; dkim=pass (2048-bit key) header.d=mavick.dev header.i=@mavick.dev header.b=i9Xo9o4D; arc=none smtp.client-ip=80.241.56.151 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mavick.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mavick.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mavick.dev header.i=@mavick.dev header.b="i9Xo9o4D" Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:b231:465::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA512) (No client certificate requested) by mout-p-101.mailbox.org (Postfix) with ESMTPS id 4gxwxt41NSz8v1p; Sat, 11 Jul 2026 06:41:06 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mavick.dev; s=MBO0001; t=1783744866; 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: in-reply-to:in-reply-to:references:references; bh=5fRYBbl/zFHo/ph55CpxjBKpforkcs9UdExdzuIQ868=; b=i9Xo9o4De01YdLlfiFfiUO4cTTk+rdHz9XoaG27qFEXE8Dr2HpfhUlzoH9sqJ5FJ5+S3p2 1UDvwaIavR7TQSjMd2scSqfFieEPssjD9yEbWuGaHjjl97INZAgw7UhSqPXsG3KssX5oKj xcgRhqffsfD+Qinnf1y0HAwo2t3xOrQyoHAKk1EHFp8fI/j/FMWUnVnO2oX/J4Or3eKz2y pJrR25bJCRYlGvZ+653qV72ImAm3q310S/yZD0u5B2l8qrtCocQ/vcpNM6NYglC458J0Ep lv/gn1+E4i0utnWL+Kf7TIy7X+dxPN3rhbY0b8GqJxF3X25uA6atUto+AAsYCg== Authentication-Results: outgoing_mbo_mout; dkim=none; spf=pass (outgoing_mbo_mout: domain of m@mavick.dev designates 2001:67c:2050:b231:465::1 as permitted sender) smtp.mailfrom=m@mavick.dev From: Eugene Mavick Date: Sat, 11 Jul 2026 12:40:19 +0800 Subject: [PATCH v3 1/5] tracing: add ref_trace_final_put tracepoint Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260711-refcount-final-put-trace-v3-1-674c8f03d9f9@mavick.dev> References: <20260711-refcount-final-put-trace-v3-0-674c8f03d9f9@mavick.dev> In-Reply-To: <20260711-refcount-final-put-trace-v3-0-674c8f03d9f9@mavick.dev> 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; a=openpgp-sha256; l=4418; i=m@mavick.dev; h=from:subject:message-id; bh=togALykcuUOAaOKZnU5+keMWktwavqkGC+6SZdVlIpU=; b=owGbwMvMwCU2V/5U3e1aE3/G02pJDFmBJ20vBxSl+CqVOyzui55aOcfuqR/rIrPjf5PmrK87L bWtzWxSRykLgxgXg6yYIktNVoJ7xspZicZHJ/XAzGFlAhnCwMUpABMpNGT4K/dCtMKuz5OT9X4p /92Sq1Pn3Shns5Xlrl2m2WT1xm5bFSPDCo7AM3P+er9OesvRs++ogfkx9pdPPt+sDmyqMPwXWHe BGwA= X-Developer-Key: i=m@mavick.dev; a=openpgp; fpr=7C6A604768A99A6133C5928C9D1FCA7EDB7D344F X-Rspamd-Queue-Id: 4gxwxt41NSz8v1p Add ref_trace_final_put tracepoint and related core infrastructure ref_trace_final_put fires when a reference count reaches zero and the object enters its final release path. 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 --- include/linux/ref_trace.h | 26 +++++++++++++++++++++++ include/trace/events/ref_trace.h | 46 ++++++++++++++++++++++++++++++++++++++++ lib/Makefile | 2 ++ lib/ref_trace.c | 13 ++++++++++++ 4 files changed, 87 insertions(+) diff --git a/include/linux/ref_trace.h b/include/linux/ref_trace.h new file mode 100644 index 000000000000..6c6600938a47 --- /dev/null +++ b/include/linux/ref_trace.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_REF_TRACE_H +#define _LINUX_REF_TRACE_H + +#include +#include + +/* Declare the tracepoint so tracepoint_enabled() can be used */ +DECLARE_TRACEPOINT(ref_trace_final_put); + +#ifdef CONFIG_TRACEPOINTS +/* Wrapper function implemented in lib/ref_trace.c */ +extern void do_ref_trace_final_put(unsigned long caller, const char *fn, const void *obj); + +#define do_trace_ref_final_put(obj) \ + do { \ + if (tracepoint_enabled(ref_trace_final_put)) \ + do_ref_trace_final_put(_RET_IP_, __func__, obj); \ + } while (0) + +#else /* !CONFIG_TRACEPOINTS */ +static inline void do_ref_trace_final_put(unsigned long caller, const char *fn, const void *obj) { } +#define do_trace_ref_final_put(obj) do { } while (0) +#endif + +#endif /* _LINUX_REF_TRACE_H */ diff --git a/include/trace/events/ref_trace.h b/include/trace/events/ref_trace.h new file mode 100644 index 000000000000..3bf1b1d390b8 --- /dev/null +++ b/include/trace/events/ref_trace.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM ref_trace + +#if !defined(_TRACE_REF_TRACE_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_REF_TRACE_H + +#include + +/** + * ref_trace_final_put - trace when a reference count reaches zero + * @caller: return address of refcount + * 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) + * + * Tracepoint instrumentation can be added using the do_ref_trace_final_put + * macro defined in include/linux/ref_trace.h + * which uses _RET_IP_ and __func__ for caller and fn arguments respectively, + * thus only requiring obj arg to be supplied + */ +TRACE_EVENT(ref_trace_final_put, + + TP_PROTO(unsigned long caller, const char *fn, const void *obj), + + TP_ARGS(caller, fn, obj), + + TP_STRUCT__entry( + __field(unsigned long, caller) + __string(fn, fn) + __field(const void *, obj) + ), + + TP_fast_assign( + __entry->caller = caller; + __assign_str(fn); + __entry->obj = obj; + ), + + TP_printk("caller=%pS fn=%s obj=%p", (void *)__entry->caller, __get_str(fn), __entry->obj) +); + +#endif /* _TRACE_REF_TRACE_H */ + +/* This part must be outside protection */ +#include diff --git a/lib/Makefile b/lib/Makefile index f33a24bf1c19..41737090a95d 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -335,3 +335,5 @@ CONTEXT_ANALYSIS_test_context-analysis.o := y obj-$(CONFIG_CONTEXT_ANALYSIS_TEST) += test_context-analysis.o subdir-$(CONFIG_FORTIFY_SOURCE) += test_fortify + +obj-$(CONFIG_TRACEPOINTS) += ref_trace.o diff --git a/lib/ref_trace.c b/lib/ref_trace.c new file mode 100644 index 000000000000..466647772ce1 --- /dev/null +++ b/lib/ref_trace.c @@ -0,0 +1,13 @@ +// SPDX-License-Identifier: GPL-2.0 +#define CREATE_TRACE_POINTS +#include +#include + +//Wrapper function for functions defined entirely in header files +void do_ref_trace_final_put(unsigned long caller, const char *fn, const void *obj) +{ + trace_call__ref_trace_final_put(caller, fn, obj); +} +EXPORT_SYMBOL_GPL(do_ref_trace_final_put); + +EXPORT_TRACEPOINT_SYMBOL_GPL(ref_trace_final_put); -- 2.51.2