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[24.6.216.183]) by smtp.gmail.com with ESMTPSA id x2-20020a170902820200b001afd821c057sm2278222pln.58.2023.05.25.22.17.44 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 May 2023 22:17:45 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3731.500.231\)) Subject: Re: [PATCH v2 2/3] compiler: inline does not imply notrace From: Nadav Amit In-Reply-To: <20230525222844.6a0d84f8@rorschach.local.home> Date: Thu, 25 May 2023 22:17:33 -0700 Cc: Arnd Bergmann , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, LKML , linux-ia64@vger.kernel.org, linux-um@lists.infradead.org, Linux-Arch , linux-mm , Andy Lutomirski , Ingo Molnar , Dave Hansen , Borislav Petkov , X86 ML , Peter Zijlstra Content-Transfer-Encoding: quoted-printable Message-Id: References: <20230525210040.3637-1-namit@vmware.com> <20230525210040.3637-3-namit@vmware.com> <20230525222844.6a0d84f8@rorschach.local.home> To: Steven Rostedt X-Mailer: Apple Mail (2.3731.500.231) Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org > On May 25, 2023, at 7:28 PM, Steven Rostedt = wrote: >=20 > On Thu, 25 May 2023 14:00:39 -0700 > Nadav Amit wrote: >=20 >> From: Nadav Amit >>=20 >> Functions that are marked as "inline" are currently also not = tracable. >> This limits tracing functionality for many functions for no reason. >> Apparently, this has been done for two reasons. >>=20 >> First, as described in commit 5963e317b1e9d2a ("ftrace/x86: Do not >> change stacks in DEBUG when calling lockdep"), it was intended to >> prevent some functions that cannot be traced from being traced as = these >> functions were marked as inline (among others). >>=20 >> Yet, this change has been done a decade ago, and according to Steven >> Rostedt, ftrace should have improved and hopefully resolved nested >> tracing issues by now. Arguably, if functions that should be traced - >> for instance since they are used during tracing - still exist, they >> should be marked as notrace explicitly. >>=20 >> The second reason, which Steven raised, is that attaching "notrace" = to >> "inline" prevented tracing differences between different configs, = which >> caused various problem. This consideration is not very strong, and = tying >> "inline" and "notrace" does not seem very beneficial. The "inline" >> keyword is just a hint, and many functions are currently not tracable >> due to this reason. >>=20 >> Disconnect "inline" from "notrace". >=20 > FYI, I have a patch queued (still needs to go through testing) that > already does this ;-) >=20 > = https://lore.kernel.org/all/20230502164102.1a51cdb4@gandalf.local.home/ Ugh. If you cc=E2=80=99d me, I wouldn=E2=80=99t bother you during your = vacation. :) I think you may like the first patch in my series to precede this patch though as some of the function I marked as =E2=80=9Cnotrace" are = currently =E2=80=9Cinline=E2=80=9D. Let me know how you want to proceed, so I would know how to break this series.