From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 82FBAF4F1; Thu, 26 Mar 2026 01:28:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774488531; cv=none; b=PfZcJtRbXoGVAEVhBuPV/c8amRd0+d9nPDDbcTRhcSRkSlozRgxI4LJvZx1N/VrC80RHM3LZ/ocKuQPJV2arhQoYk01jYtCCA0qkqOho9eL/k0wiHSDMoc/DEqUrWTYJt3YsffIBxctROBTU7nowukEM4Y3mghA7t7ve9zuE9P4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774488531; c=relaxed/simple; bh=0Cq7OMqDyz29Hy/YQIvOOTgh39yp/jjxAwDycnlq/O0=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=WUy6Adt/wTSA2KclWJzTRK3DBM6NvXfdRYO9O51OS3uJiN2S7VmuEBVqfV8fJKFB2cSIbxPioovUs2hkuyPWfq91a2RmVbTK4c8EEq1oxtWUObO/STRlK9n4A+qNfMA5NFkC4CyQ1uy1srPr8fUy2zIJnxggaM3wMmZZPJef4YM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MLfhqhkz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MLfhqhkz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3592AC4CEF7; Thu, 26 Mar 2026 01:28:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774488531; bh=0Cq7OMqDyz29Hy/YQIvOOTgh39yp/jjxAwDycnlq/O0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MLfhqhkzsxa7tc0jHzhytzV6qchl81dHU9KAPgpYRYmOHYLzk4wblKHPtqEHyv28p Q/b1ZGVBAKVMA2DtsWIH4xs0i1VJ2p7crVWlc/njQGIq3j2rxJcz4zZlqQtGtXSKGY qE7kmn3skAAmdHpynUh6G1IcDYzRBpRJQJ2v9dHtuEYl1SHM9u79m3ODxDTtFbRHwF TrXVRIXikjQcC748T/h8YzRRuj5Is74hno4IqadGPqhCATzpJM+vXtHmT1645lImlw xbcKSEnaeY6vjDCFgor9rDZ7RPAf5TB+nN0PUncVs3G3ToCrGTMxxDR5q52eHlIdvK yL93d9yknBOTA== Date: Thu, 26 Mar 2026 10:28:40 +0900 From: Masami Hiramatsu (Google) To: "Vineeth Pillai (Google)" Cc: Steven Rostedt , Peter Zijlstra , Dmitry Ilvokhin , 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 , Christian =?UTF-8?B?S8O2bmln?= , 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 , Nuno =?UTF-8?B?U8Oh?= , 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: Re: [PATCH v2 01/19] tracepoint: Add trace_call__##name() API Message-Id: <20260326102840.80a270ec818fea7e000aeef4@kernel.org> In-Reply-To: <20260323160052.17528-2-vineeth@bitbyteword.org> References: <20260323160052.17528-1-vineeth@bitbyteword.org> <20260323160052.17528-2-vineeth@bitbyteword.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 23 Mar 2026 12:00:20 -0400 "Vineeth Pillai (Google)" wrote: > 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 */ nit: trace_call_foo() instead of trace_invoke_foo()? Anyway looks good to me. Acked-by: Masami Hiramatsu (Google) > > 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 > -- Masami Hiramatsu (Google)