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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD601CCA483 for ; Thu, 9 Jun 2022 09:17:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241141AbiFIJRB (ORCPT ); Thu, 9 Jun 2022 05:17:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233025AbiFIJQz (ORCPT ); Thu, 9 Jun 2022 05:16:55 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9AA0E1A046; Thu, 9 Jun 2022 02:16:53 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 31C7E1FDAF; Thu, 9 Jun 2022 09:16:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1654766212; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=d57/DrqDiiJ2foYz2ew+5Cqn+PqODCYrsHqzu7X2C2Q=; b=fo+sYmFjpmQOmpyD3JvJl9AYNinBjxAVeUE+HbamyvnKBmUJ4aJ/YSAu3A8+CqB7Ibeuz8 5d8JOsM43+X+4Im3fKziKImYEhGOTr+/e/e7kKF981tYnqb1CU7vBLnpyqhaj1HOQaPm0q 8dfR9EB/TBh2sOsSKiFiTu8q7nOVsPQ= Received: from suse.cz (unknown [10.100.208.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id B45BB2C14F; Thu, 9 Jun 2022 09:16:46 +0000 (UTC) Date: Thu, 9 Jun 2022 11:16:46 +0200 From: Petr Mladek To: Peter Zijlstra Cc: ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@hansenpartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, senozhatsky@chromium.org, john.ogness@linutronix.de, paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org Subject: Re: [PATCH 24/36] printk: Remove trace_.*_rcuidle() usage Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.444659212@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220608144517.444659212@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org On Wed 2022-06-08 16:27:47, Peter Zijlstra wrote: > The problem, per commit fc98c3c8c9dc ("printk: use rcuidle console > tracepoint"), was printk usage from the cpuidle path where RCU was > already disabled. > > Per the patches earlier in this series, this is no longer the case. My understanding is that this series reduces a lot the amount of code called with RCU disabled. As a result the particular printk() call mentioned by commit fc98c3c8c9dc ("printk: use rcuidle console tracepoint") is called with RCU enabled now. Hence this particular problem is fixed better way now. But is this true in general? Does this "prevent" calling printk() a safe way in code with RCU disabled? I am not sure if anyone cares. printk() is the best effort functionality because of the consoles code anyway. Also I wonder if anyone uses this trace_console(). Therefore if this patch allows to remove some tricky tracing code then it might be worth it. But if trace_console_rcuidle() variant is still going to be available then I would keep using it. Best Regards, Petr > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/printk/printk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -2238,7 +2238,7 @@ static u16 printk_sprint(char *text, u16 > } > } > > - trace_console_rcuidle(text, text_len); > + trace_console(text, text_len); > > return text_len; > } > 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 smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 20DA4C43334 for ; Thu, 9 Jun 2022 09:16:59 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 9744A4018F; Thu, 9 Jun 2022 09:16:58 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id p4D12LTBhh_t; 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Thu, 9 Jun 2022 09:16:54 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 317C521DE0; Thu, 9 Jun 2022 09:16:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1654766212; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=d57/DrqDiiJ2foYz2ew+5Cqn+PqODCYrsHqzu7X2C2Q=; b=fo+sYmFjpmQOmpyD3JvJl9AYNinBjxAVeUE+HbamyvnKBmUJ4aJ/YSAu3A8+CqB7Ibeuz8 5d8JOsM43+X+4Im3fKziKImYEhGOTr+/e/e7kKF981tYnqb1CU7vBLnpyqhaj1HOQaPm0q 8dfR9EB/TBh2sOsSKiFiTu8q7nOVsPQ= Received: from suse.cz (unknown [10.100.208.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id B45BB2C14F; Thu, 9 Jun 2022 09:16:46 +0000 (UTC) Date: Thu, 9 Jun 2022 11:16:46 +0200 To: Peter Zijlstra Subject: Re: [PATCH 24/36] printk: Remove trace_.*_rcuidle() usage Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.444659212@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220608144517.444659212@infradead.org> Cc: juri.lelli@redhat.com, rafael@kernel.org, benh@kernel.crashing.org, 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, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, mturquette@baylibre.com, sammy@sammy.net, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.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, paulus@samba.org, 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, quic_neeraju@quicinc.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, mathieu.desnoyers@efficios.com, frederic@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, shorne@gmail.com, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, 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, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, 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, paulmck@kernel.org, hca@linux.ibm.com, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, ink@jurassic.park.msu.ru, 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: , From: Petr Mladek via Virtualization Reply-To: Petr Mladek Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Wed 2022-06-08 16:27:47, Peter Zijlstra wrote: > The problem, per commit fc98c3c8c9dc ("printk: use rcuidle console > tracepoint"), was printk usage from the cpuidle path where RCU was > already disabled. > > Per the patches earlier in this series, this is no longer the case. My understanding is that this series reduces a lot the amount of code called with RCU disabled. As a result the particular printk() call mentioned by commit fc98c3c8c9dc ("printk: use rcuidle console tracepoint") is called with RCU enabled now. Hence this particular problem is fixed better way now. But is this true in general? Does this "prevent" calling printk() a safe way in code with RCU disabled? I am not sure if anyone cares. printk() is the best effort functionality because of the consoles code anyway. Also I wonder if anyone uses this trace_console(). Therefore if this patch allows to remove some tricky tracing code then it might be worth it. But if trace_console_rcuidle() variant is still going to be available then I would keep using it. Best Regards, Petr > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/printk/printk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -2238,7 +2238,7 @@ static u16 printk_sprint(char *text, u16 > } > } > > - trace_console_rcuidle(text, text_len); > + trace_console(text, text_len); > > return text_len; > } > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization 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 mail.librecores.org (lists.librecores.org [88.198.125.70]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3FE9C43334 for ; Thu, 9 Jun 2022 10:42:01 +0000 (UTC) Received: from [172.31.1.100] (localhost.localdomain [127.0.0.1]) by mail.librecores.org (Postfix) with ESMTP id 9AC1B248F2; 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Thu, 9 Jun 2022 09:16:46 +0000 (UTC) Date: Thu, 9 Jun 2022 11:16:46 +0200 From: Petr Mladek To: Peter Zijlstra Subject: Re: [PATCH 24/36] printk: Remove trace_.*_rcuidle() usage Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.444659212@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220608144517.444659212@infradead.org> X-Mailman-Approved-At: Thu, 09 Jun 2022 12:41:56 +0200 X-BeenThere: openrisc@lists.librecores.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Discussion around the OpenRISC processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: juri.lelli@redhat.com, rafael@kernel.org, benh@kernel.crashing.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, srivatsa@csail.mit.edu, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, mpe@ellerman.id.au, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, borntraeger@linux.ibm.com, mturquette@baylibre.com, sammy@sammy.net, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.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, paulus@samba.org, 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, quic_neeraju@quicinc.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, mathieu.desnoyers@efficios.com, frederic@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, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, 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, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, 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, paulmck@kernel.org, hca@linux.ibm.com, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org Errors-To: openrisc-bounces@lists.librecores.org Sender: "OpenRISC" On Wed 2022-06-08 16:27:47, Peter Zijlstra wrote: > The problem, per commit fc98c3c8c9dc ("printk: use rcuidle console > tracepoint"), was printk usage from the cpuidle path where RCU was > already disabled. > > Per the patches earlier in this series, this is no longer the case. My understanding is that this series reduces a lot the amount of code called with RCU disabled. As a result the particular printk() call mentioned by commit fc98c3c8c9dc ("printk: use rcuidle console tracepoint") is called with RCU enabled now. Hence this particular problem is fixed better way now. But is this true in general? Does this "prevent" calling printk() a safe way in code with RCU disabled? I am not sure if anyone cares. printk() is the best effort functionality because of the consoles code anyway. Also I wonder if anyone uses this trace_console(). Therefore if this patch allows to remove some tricky tracing code then it might be worth it. But if trace_console_rcuidle() variant is still going to be available then I would keep using it. Best Regards, Petr > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/printk/printk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -2238,7 +2238,7 @@ static u16 printk_sprint(char *text, u16 > } > } > > - trace_console_rcuidle(text, text_len); > + trace_console(text, text_len); > > return text_len; > } > 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6B87EC43334 for ; Fri, 10 Jun 2022 11:12:10 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LKJFh4JDtz3cjY for ; Fri, 10 Jun 2022 21:12:08 +1000 (AEST) Authentication-Results: lists.ozlabs.org; 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Thu, 9 Jun 2022 09:16:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1654766212; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=d57/DrqDiiJ2foYz2ew+5Cqn+PqODCYrsHqzu7X2C2Q=; b=fo+sYmFjpmQOmpyD3JvJl9AYNinBjxAVeUE+HbamyvnKBmUJ4aJ/YSAu3A8+CqB7Ibeuz8 5d8JOsM43+X+4Im3fKziKImYEhGOTr+/e/e7kKF981tYnqb1CU7vBLnpyqhaj1HOQaPm0q 8dfR9EB/TBh2sOsSKiFiTu8q7nOVsPQ= Received: from suse.cz (unknown [10.100.208.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id B45BB2C14F; Thu, 9 Jun 2022 09:16:46 +0000 (UTC) Date: Thu, 9 Jun 2022 11:16:46 +0200 From: Petr Mladek To: Peter Zijlstra Subject: Re: [PATCH 24/36] printk: Remove trace_.*_rcuidle() usage Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.444659212@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220608144517.444659212@infradead.org> X-Mailman-Approved-At: Fri, 10 Jun 2022 21:09:20 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: juri.lelli@redhat.com, rafael@kernel.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, srivatsa@csail.mit.edu, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, borntraeger@linux.ibm.com, mturquette@baylibre.com, sammy@sammy.net, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.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, paulus@samba.org, 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, quic_neeraju@quicinc.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, mathieu.desnoyers@efficios.com, frederic@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, shorne@gmail.com, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, 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.p an@linux.intel.com, Arnd Bergmann , ul li.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, tony@atomide.com, amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, 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, paulmck@kernel.org, hca@linux.ibm.com, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, monstr@monstr.eu, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, ink@ jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed 2022-06-08 16:27:47, Peter Zijlstra wrote: > The problem, per commit fc98c3c8c9dc ("printk: use rcuidle console > tracepoint"), was printk usage from the cpuidle path where RCU was > already disabled. > > Per the patches earlier in this series, this is no longer the case. My understanding is that this series reduces a lot the amount of code called with RCU disabled. As a result the particular printk() call mentioned by commit fc98c3c8c9dc ("printk: use rcuidle console tracepoint") is called with RCU enabled now. Hence this particular problem is fixed better way now. But is this true in general? Does this "prevent" calling printk() a safe way in code with RCU disabled? I am not sure if anyone cares. printk() is the best effort functionality because of the consoles code anyway. Also I wonder if anyone uses this trace_console(). Therefore if this patch allows to remove some tricky tracing code then it might be worth it. But if trace_console_rcuidle() variant is still going to be available then I would keep using it. Best Regards, Petr > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/printk/printk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -2238,7 +2238,7 @@ static u16 printk_sprint(char *text, u16 > } > } > > - trace_console_rcuidle(text, text_len); > + trace_console(text, text_len); > > return text_len; > } > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Mladek Date: Thu, 09 Jun 2022 09:16:46 +0000 Subject: Re: [PATCH 24/36] printk: Remove trace_.*_rcuidle() usage Message-Id: List-Id: References: <20220608142723.103523089@infradead.org> <20220608144517.444659212@infradead.org> In-Reply-To: <20220608144517.444659212@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@hansenpartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, senozhatsky@chromium.org, john.ogness@linutronix.de, paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org On Wed 2022-06-08 16:27:47, Peter Zijlstra wrote: > The problem, per commit fc98c3c8c9dc ("printk: use rcuidle console > tracepoint"), was printk usage from the cpuidle path where RCU was > already disabled. > > Per the patches earlier in this series, this is no longer the case. My understanding is that this series reduces a lot the amount of code called with RCU disabled. As a result the particular printk() call mentioned by commit fc98c3c8c9dc ("printk: use rcuidle console tracepoint") is called with RCU enabled now. Hence this particular problem is fixed better way now. But is this true in general? Does this "prevent" calling printk() a safe way in code with RCU disabled? I am not sure if anyone cares. printk() is the best effort functionality because of the consoles code anyway. Also I wonder if anyone uses this trace_console(). Therefore if this patch allows to remove some tricky tracing code then it might be worth it. But if trace_console_rcuidle() variant is still going to be available then I would keep using it. Best Regards, Petr > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/printk/printk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -2238,7 +2238,7 @@ static u16 printk_sprint(char *text, u16 > } > } > > - trace_console_rcuidle(text, text_len); > + trace_console(text, text_len); > > return text_len; > } > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Petr Mladek Subject: Re: [PATCH 24/36] printk: Remove trace_.*_rcuidle() usage Date: Thu, 9 Jun 2022 11:16:46 +0200 Message-ID: References: <20220608142723.103523089@infradead.org> <20220608144517.444659212@infradead.org> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1654766212; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=d57/DrqDiiJ2foYz2ew+5Cqn+PqODCYrsHqzu7X2C2Q=; b=fo+sYmFjpmQOmpyD3JvJl9AYNinBjxAVeUE+HbamyvnKBmUJ4aJ/YSAu3A8+CqB7Ibeuz8 5d8JOsM43+X+4Im3fKziKImYEhGOTr+/e/e7kKF981tYnqb1CU7vBLnpyqhaj1HOQaPm0q 8dfR9EB/TBh2sOsSKiFiTu8q7nOVsPQ= Content-Disposition: inline In-Reply-To: <20220608144517.444659212@infradead.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Zijlstra Cc: ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@hansenpartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, On Wed 2022-06-08 16:27:47, Peter Zijlstra wrote: > The problem, per commit fc98c3c8c9dc ("printk: use rcuidle console > tracepoint"), was printk usage from the cpuidle path where RCU was > already disabled. > > Per the patches earlier in this series, this is no longer the case. My understanding is that this series reduces a lot the amount of code called with RCU disabled. As a result the particular printk() call mentioned by commit fc98c3c8c9dc ("printk: use rcuidle console tracepoint") is called with RCU enabled now. Hence this particular problem is fixed better way now. But is this true in general? Does this "prevent" calling printk() a safe way in code with RCU disabled? I am not sure if anyone cares. printk() is the best effort functionality because of the consoles code anyway. Also I wonder if anyone uses this trace_console(). Therefore if this patch allows to remove some tricky tracing code then it might be worth it. But if trace_console_rcuidle() variant is still going to be available then I would keep using it. Best Regards, Petr > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/printk/printk.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -2238,7 +2238,7 @@ static u16 printk_sprint(char *text, u16 > } > } > > - trace_console_rcuidle(text, text_len); > + trace_console(text, text_len); > > return text_len; > } >