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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260705-refcount-final-put-trace-v1-1-a41d3fd0e869@mavick.dev> References: <20260705-refcount-final-put-trace-v1-0-a41d3fd0e869@mavick.dev> In-Reply-To: <20260705-refcount-final-put-trace-v1-0-a41d3fd0e869@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=4836; i=m@mavick.dev; h=from:subject:message-id; bh=qHwnbzvpK9wYBzbeGmnuCtzzLwF8aY1zM3ldVu/OfqE=; b=owGbwMvMwCU2V/5U3e1aE3/G02pJDFmey20tX0Uv+uo9wcO1T/IDF/s+XU9nj3XtiUxM00Jnn 2Bi49neUcrCIMbFICumyFKTleCesXJWovHRST0wc1iZQIYwcHEKwETWVTL8T2+7m3q0rGDbIYVf tlNavGeYX9rGcrNgn13McuubTG885Bj+Z4t5HgmRc08+Wnty8xrdb2GHFuzybQq7eF59bYOWdoM mIwA= X-Developer-Key: i=m@mavick.dev; a=openpgp; fpr=7C6A604768A99A6133C5928C9D1FCA7EDB7D344F X-Stat-Signature: nwhkad1g7jtnmta16yo9rmeruijcs9bb X-Rspamd-Queue-Id: 8E6A7140006 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1783320202-664514 X-HE-Meta: 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 oMt16t8e JpsPFJL7KZmp4OAtDWtzwZYuIWT90G3PMGTYmVpJRG913cgkBpqgkP6H7RBkL3vp5ZT6woPgLdPVCd0KJ36AVGTiTtobxc2dlRpRGyfQi6ovZQjbYFwve1on5OADgLlHegKw65bjZQtk2qaA8ZuxXdCKhC9TNbD3rK31EyEd5Zlo5l6kZWVSlUPO6HIR3pQOo8d6SAOEurBEkMBJzuKBZ0xNfMbwtWCo9NvB5MfIMvyg2bMIXRyY2VbUOM44ZiWah8hjg Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 --- MAINTAINERS | 2 ++ include/linux/ref_trace.h | 26 +++++++++++++++++++++++ include/trace/events/ref_trace.h | 46 ++++++++++++++++++++++++++++++++++++++++ lib/Makefile | 2 ++ lib/ref_trace.c | 12 +++++++++++ 5 files changed, 88 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index 10e8253181d3..8dab37726b9d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -4210,7 +4210,9 @@ S: Maintained F: Documentation/atomic_*.txt F: arch/*/include/asm/atomic*.h F: include/*/atomic*.h +F: include/linux/ref_trace.h F: include/linux/refcount.h +F: lib/ref_trace.h F: scripts/atomic/ F: rust/kernel/sync/atomic.rs F: rust/kernel/sync/atomic/ diff --git a/include/linux/ref_trace.h b/include/linux/ref_trace.h new file mode 100644 index 000000000000..54e9fba9e3e9 --- /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 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 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..e6037a325be2 --- /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: 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) + * + * Tracepoint instrumentation can be added using the 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..25f7c17c7c47 --- /dev/null +++ b/lib/ref_trace.c @@ -0,0 +1,12 @@ +// SPDX-License-Identifier: GPL-2.0 +#define CREATE_TRACE_POINTS +#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_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