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[73.143.21.186]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cfc9088df1sm843364185a.25.2026.03.23.09.00.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Mar 2026 09:01:00 -0700 (PDT) From: "Vineeth Pillai (Google)" To: Steven Rostedt , Peter Zijlstra , Dmitry Ilvokhin Cc: "Vineeth Pillai (Google)" , Masami Hiramatsu , Mathieu Desnoyers , Ingo Molnar , Jens Axboe , io-uring@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Marcelo Ricardo Leitner , Xin Long , Jon Maloy , Aaron Conole , Eelco Chaudron , Ilya Maximets , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-sctp@vger.kernel.org, tipc-discussion@lists.sourceforge.net, dev@openvswitch.org, Jiri Pirko , Oded Gabbay , Koby Elbaz , dri-devel@lists.freedesktop.org, "Rafael J. Wysocki" , Viresh Kumar , "Gautham R. Shenoy" , Huang Rui , Mario Limonciello , Len Brown , Srinivas Pandruvada , linux-pm@vger.kernel.org, MyungJoo Ham , Kyungmin Park , Chanwoo Choi , =?UTF-8?q?Christian=20K=C3=B6nig?= , Sumit Semwal , linaro-mm-sig@lists.linaro.org, Eddie James , Andrew Jeffery , Joel Stanley , linux-fsi@lists.ozlabs.org, David Airlie , Simona Vetter , Alex Deucher , Danilo Krummrich , Matthew Brost , Philipp Stanner , Harry Wentland , Leo Li , amd-gfx@lists.freedesktop.org, Jiri Kosina , Benjamin Tissoires , linux-input@vger.kernel.org, Wolfram Sang , linux-i2c@vger.kernel.org, Mark Brown , Michael Hennerich , =?UTF-8?q?Nuno=20S=C3=A1?= , linux-spi@vger.kernel.org, "James E.J. Bottomley" , "Martin K. Petersen" , linux-scsi@vger.kernel.org, Chris Mason , David Sterba , linux-btrfs@vger.kernel.org, Thomas Gleixner , Andrew Morton , SeongJae Park , linux-mm@kvack.org, Borislav Petkov , Dave Hansen , x86@kernel.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 01/19] tracepoint: Add trace_call__##name() API Date: Mon, 23 Mar 2026 12:00:20 -0400 Message-ID: <20260323160052.17528-2-vineeth@bitbyteword.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323160052.17528-1-vineeth@bitbyteword.org> References: <20260323160052.17528-1-vineeth@bitbyteword.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add trace_call__##name() as a companion to trace_##name(). When a caller already guards a tracepoint with an explicit enabled check: if (trace_foo_enabled() && cond) trace_foo(args); trace_foo() internally repeats the static_branch_unlikely() test, which the compiler cannot fold since static branches are patched binary instructions. This results in two static-branch evaluations for every guarded call site. trace_call__##name() calls __do_trace_##name() directly, skipping the redundant static-branch re-check. This avoids leaking the internal __do_trace_##name() symbol into call sites while still eliminating the double evaluation: if (trace_foo_enabled() && cond) trace_invoke_foo(args); /* calls __do_trace_foo() directly */ Three locations are updated: - __DECLARE_TRACE: invoke form omits static_branch_unlikely, retains the LOCKDEP RCU-watching assertion. - __DECLARE_TRACE_SYSCALL: same, plus retains might_fault(). - !TRACEPOINTS_ENABLED stub: empty no-op so callers compile cleanly when tracepoints are compiled out. Suggested-by: Steven Rostedt Suggested-by: Peter Zijlstra Signed-off-by: Vineeth Pillai (Google) Assisted-by: Claude:claude-sonnet-4-6 --- include/linux/tracepoint.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 22ca1c8b54f32..ed969705341f1 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -294,6 +294,10 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) WARN_ONCE(!rcu_is_watching(), \ "RCU not watching for tracepoint"); \ } \ + } \ + static inline void trace_call__##name(proto) \ + { \ + __do_trace_##name(args); \ } #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto) \ @@ -313,6 +317,11 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) WARN_ONCE(!rcu_is_watching(), \ "RCU not watching for tracepoint"); \ } \ + } \ + static inline void trace_call__##name(proto) \ + { \ + might_fault(); \ + __do_trace_##name(args); \ } /* @@ -398,6 +407,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) #define __DECLARE_TRACE_COMMON(name, proto, args, data_proto) \ static inline void trace_##name(proto) \ { } \ + static inline void trace_call__##name(proto) \ + { } \ static inline int \ register_trace_##name(void (*probe)(data_proto), \ void *data) \ -- 2.53.0