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Mon, 26 Sep 2022 18:41:06 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 70D3BB80D67; Mon, 26 Sep 2022 18:41:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8346C433D7; Mon, 26 Sep 2022 18:40:49 +0000 (UTC) Date: Mon, 26 Sep 2022 14:41:57 -0400 From: Steven Rostedt To: Peter Zijlstra Subject: Re: [PATCH v2 33/44] ftrace: WARN on rcuidle Message-ID: <20220926144157.0406dfbb@gandalf.local.home> In-Reply-To: <20220919101522.573936213@infradead.org> References: <20220919095939.761690562@infradead.org> <20220919101522.573936213@infradead.org> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Cc: juri.lelli@redhat.com, rafael@kernel.org, catalin.marinas@arm.com, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, mpe@ellerman.id.au, chenhuacai@kernel.org, christophe.leroy@csgroup.eu, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, vgupta@kernel.org, mattst88@gmail.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, Sascha Hauer , linux-um@lists.infradead.org, npiggin@gmail.com, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, andreyknvl@gmail.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, tj@kernel.org, Andrew Morton , mark.rutland@arm.com, linux-ia64@vger.kernel.org, dave.hansen@linux.intel.com, virtualization@lists.linux-foundation.org, James.Bottomley@HansenPartnership.com, jcmvbkbc@gmail.com, thierry.reding@gmail.com, kernel@xen0n.name, cl@linux.com, linux-s390@vger.kernel.org, vschneid@redhat.com, john.ogness@linutronix.de, ysato@users.sourceforge.jp, linux-sh@vger.kernel.org, festevam@gmail.com, deller@gmx.de, daniel.lezcano@linaro.org, jonathanh@nvidia.com, dennis@kernel.org, lenb@kernel.org, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de, gor@linux.ibm.com, linux-arm-msm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-m68k@lists.linux-m68k.org, loongarch@lists.linux.dev, shorne@gmail.com, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, fweisbec@gmail.com, lpieralisi@kernel.org, atishp@atishpatra.org, linux@rasmusvillemoes.dk, kasan-dev@googlegroups.com, will@kernel.org, boris.ostrovsky@oracle.com, khilman@kernel.org, linux-csky@vger.kernel.org, pv-drivers@vmware.com, linux-snps-arc@lists.infradead.org, mgorman@suse.de, jacob.jun.pan@linux.intel.com, Arnd Bergmann , ulli.kroll@googlemail.com, linux-clk@vger.kernel.org, ink@jurassic.park.msu.ru, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, ryabinin.a.a@gmail.com, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, konrad.dybcio@somainline.org, bjorn.andersson@linaro.org, glider@google.com, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, vincenzo.frascino@arm.com, anton.ivanov@cambridgegreys.com, jonas@southpole.se, yury.norov@gmail.com, richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, richard.henderson@linaro.org, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, acme@kernel.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, dvyukov@google.com, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, bp@alien8.de, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" Nit, the subject should have "tracing:" an not "ftrace:" as the former encompasses the tracing infrastructure and the latter is for the function hook part of that. On Mon, 19 Sep 2022 12:00:12 +0200 Peter Zijlstra wrote: > CONFIG_GENERIC_ENTRY disallows any and all tracing when RCU isn't > enabled. > > XXX if s390 (the only other GENERIC_ENTRY user as of this writing) > isn't comfortable with this, we could switch to > HAVE_NOINSTR_VALIDATION which is x86_64 only atm. > > Signed-off-by: Peter Zijlstra (Intel) > --- > include/linux/tracepoint.h | 13 ++++++++++++- > kernel/trace/trace.c | 3 +++ > 2 files changed, 15 insertions(+), 1 deletion(-) > > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -178,6 +178,16 @@ static inline struct tracepoint *tracepo > #endif /* CONFIG_HAVE_STATIC_CALL */ > > /* > + * CONFIG_GENERIC_ENTRY archs are expected to have sanitized entry and idle > + * code that disallow any/all tracing/instrumentation when RCU isn't watching. > + */ > +#ifdef CONFIG_GENERIC_ENTRY > +#define RCUIDLE_COND(rcuidle) (rcuidle) > +#else Should probably move the below comment to here: /* srcu can't be used from NMI */ > +#define RCUIDLE_COND(rcuidle) (rcuidle && in_nmi()) > +#endif > + > +/* > * it_func[0] is never NULL because there is at least one element in the array > * when the array itself is non NULL. > */ > @@ -189,7 +199,8 @@ static inline struct tracepoint *tracepo > return; \ > \ > /* srcu can't be used from NMI */ \ And remove the above. -- Steve > - WARN_ON_ONCE(rcuidle && in_nmi()); \ > + if (WARN_ON_ONCE(RCUIDLE_COND(rcuidle))) \ > + return; \ > \ > /* keep srcu and sched-rcu usage consistent */ \ > preempt_disable_notrace(); \ > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -3104,6 +3104,9 @@ void __trace_stack(struct trace_array *t > return; > } > > + if (WARN_ON_ONCE(IS_ENABLED(CONFIG_GENERIC_ENTRY))) > + return; > + > /* > * When an NMI triggers, RCU is enabled via ct_nmi_enter(), > * but if the above rcu_is_watching() failed, then the NMI > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization