From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 599F7CAC59A for ; Thu, 18 Sep 2025 16:13:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 95CB28E0149; Thu, 18 Sep 2025 12:13:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 90B288E00F6; Thu, 18 Sep 2025 12:13:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 847F28E0149; Thu, 18 Sep 2025 12:13:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 703E28E00F6 for ; Thu, 18 Sep 2025 12:13:27 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 1FCE2C0240 for ; Thu, 18 Sep 2025 16:13:27 +0000 (UTC) X-FDA: 83902866054.21.0134C95 Received: from relay.hostedemail.com (unirelay06 [10.200.18.69]) by imf05.hostedemail.com (Postfix) with ESMTP id 3FDD1100012 for ; Thu, 18 Sep 2025 16:13:25 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1758212005; h=from:from:sender: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=QYza+B6UX/oNghkY805fNwVtOdXsgka//Us/2M2ST3g=; b=tzs2AjyZRzFhiYmLtaZmHYcSh/al+evM7djqIDgPYdRqSGVwRU+uPSgq4q8NjxV1KdrVUD 4H2sFH6spfQE+Xie6wzUEJRzoGYV0vlMUB1x/mBJQu6p3L3ISGPzUUANgvV3me5ltDTuxg BRU+FRLmrZoCyXzTubnht6No6RLv26s= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1758212005; a=rsa-sha256; cv=none; b=ljdrs/RhMytaEGkjhfvz/Crna4rVbTKsDWjx8XmvXxRsh7twaql0ft8lVbYPfWpzrATf78 ZVtXq2oUpb7GOHP3pK8JXwHQ5lU7Hi0fapjMEflSUI4tGyC6oH1+itMi1XJ70YyRedW+U4 mzzDr2ZKLJRt+2yA8mEt2fhRGqOCKGU= ARC-Authentication-Results: i=1; imf05.hostedemail.com; none Received: from omf15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 0D508118E89; Thu, 18 Sep 2025 16:13:21 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf15.hostedemail.com (Postfix) with ESMTPA id 2846618; Thu, 18 Sep 2025 16:13:08 +0000 (UTC) Date: Thu, 18 Sep 2025 12:14:16 -0400 From: Steven Rostedt To: Bart Van Assche Cc: Ian Rogers , Marco Elver , Peter Zijlstra , Boqun Feng , Ingo Molnar , Will Deacon , "David S. Miller" , Luc Van Oostenryck , "Paul E. McKenney" , Alexander Potapenko , Arnd Bergmann , Bill Wendling , Christoph Hellwig , Dmitry Vyukov , Eric Dumazet , Frederic Weisbecker , Greg Kroah-Hartman , Herbert Xu , Jann Horn , Joel Fernandes , Jonathan Corbet , Josh Triplett , Justin Stitt , Kees Cook , Kentaro Takeda , Lukas Bulwahn , Mark Rutland , Mathieu Desnoyers , Miguel Ojeda , Nathan Chancellor , Neeraj Upadhyay , Nick Desaulniers , Tetsuo Handa , Thomas Gleixner , Thomas Graf , Uladzislau Rezki , Waiman Long , kasan-dev@googlegroups.com, linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-sparse@vger.kernel.org, llvm@lists.linux.dev, rcu@vger.kernel.org Subject: Re: [PATCH v3 02/35] compiler-capability-analysis: Add infrastructure for Clang's capability analysis Message-ID: <20250918121416.19a8041e@gandalf.local.home> In-Reply-To: <1ca90ba0-7bdc-43d1-af12-bba73dd3234a@acm.org> References: <20250918140451.1289454-1-elver@google.com> <20250918140451.1289454-3-elver@google.com> <1ca90ba0-7bdc-43d1-af12-bba73dd3234a@acm.org> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX187tFXsL5Le7f+OEdXPb8EfevPMdYJjxao= X-HE-Meta: U2FsdGVkX19m1tAn22PHk3kX2Wk2POBgAZFzgAQIMCx/TzKCFJHSRgy7lqGNU4t4JpUf2LxrofFc8Ml/SzvQUemqI2s/M2eVv2TcCTTofn0gFGf1qiKnggle2+rBi9jozqgLP+w5zmTzD8j5BYGNETdC7HYpSCmlxzgRl1HmUDgT6vBPRbNQKlew/GiSPntamWI4BN+3BQMlrQzHKrw2Hd44nH0TJbDzGUvq4EnHN5l77wWkx8yamYKm0wF/UonjU1auAq1+e+AHgLIMHgDBTy/q+l9/HvzB2gWDjclvwsnGTS+Jv2LDmjZbgWOiLNXP1sp9TafIX1LTwyRs55KIsTFDvD2gur62c5R5bpv6t02yJBvS9Pt6FACmEbxkfSaUp1nLcDU5Q19B7Ha8v33a91ClwZlXoj1UYYAtqvo6OkbX+GZwbhQ0RoFfAYIW3JVWEzxWKbCA0qFysRVjwJOtsFC2FqAYNCgDAkEhxNFg1LQ= X-Stat-Signature: oyrrhu7nbq6ifkoonpoonkjsywp67qgd X-HE-Tag-Orig: 1758211988-794253 X-Rspamd-Queue-Id: 3FDD1100012 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1758212005-681569 X-HE-Meta: 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 uMa2Al9N pxD2B3E6WIUXr13hn7zxL1MpgnqCJEpctkVgZAyrhueAvnDU7zktNMNABD1S8VxvSCNaB8IjX0Oi+d4cUC+aHKKTVMlQU9eY3ZeRyWhTIDG1nUqzGQMZN4amdQfZSiA7D4aUdM404Dd7N6wTZNNp1iUh6hbFnNcBMcyOfAYNNbm0gSI4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 18 Sep 2025 09:03:17 -0700 Bart Van Assche wrote: > On 9/18/25 8:58 AM, Ian Rogers wrote: > > On Thu, Sep 18, 2025 at 7:05=E2=80=AFAM Marco Elver = wrote: =20 > >> +config WARN_CAPABILITY_ANALYSIS > >> + bool "Compiler capability-analysis warnings" > >> + depends on CC_IS_CLANG && CLANG_VERSION >=3D 220000 > >> + # Branch profiling re-defines "if", which messes with the comp= iler's > >> + # ability to analyze __cond_acquires(..), resulting in false p= ositives. > >> + depends on !TRACE_BRANCH_PROFILING =20 > >=20 > > Err, wow! What and huh, and why? Crikes. I'm amazed you found such an > > option exists. I must be very naive to have never heard of it and now > > I wonder if it is needed and load bearing? =20 >=20 > (+Steven) >=20 > This is an old option. I think this commit introduced it: >=20 > commit 52f232cb720a7babb752849cbc2cab2d24021209 > Author: Steven Rostedt > Date: Wed Nov 12 00:14:40 2008 -0500 >=20 > tracing: likely/unlikely branch annotation tracer >=20 I still use it every year (enable it during December for a few weeks on my workstation and server) and post the results publicly. When I get time, I try to fix (add / remove) likely/unlikely statements. Unfortunately, I haven't had time to look deeper at them. https://rostedt.org/branches/current/ This year I missed December and ended up running it in January instead. -- Steve