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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD845C43A1D for ; Thu, 12 Jul 2018 13:35:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 87D152147C for ; Thu, 12 Jul 2018 13:35:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 87D152147C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727597AbeGLNov (ORCPT ); Thu, 12 Jul 2018 09:44:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:47868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726782AbeGLNov (ORCPT ); Thu, 12 Jul 2018 09:44:51 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 188BF213A2; Thu, 12 Jul 2018 13:35:14 +0000 (UTC) Date: Thu, 12 Jul 2018 09:35:12 -0400 From: Steven Rostedt To: Joel Fernandes Cc: "Paul E. McKenney" , Peter Zijlstra , linux-kernel@vger.kernel.org, Boqun Feng , Byungchul Park , Ingo Molnar , Julia Cartwright , linux-kselftest@vger.kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Namhyung Kim , Thomas Glexiner , Tom Zanussi Subject: Re: [PATCH v9 4/7] tracepoint: Make rcuidle tracepoint callers use SRCU Message-ID: <20180712093512.1f612a24@gandalf.local.home> In-Reply-To: <20180712042825.GA154647@joelaf.mtv.corp.google.com> References: <20180628182149.226164-1-joel@joelfernandes.org> <20180628182149.226164-5-joel@joelfernandes.org> <20180711124954.GE2476@hirez.programming.kicks-ass.net> <20180711090003.42596c2b@gandalf.local.home> <20180711142744.GN3593@linux.vnet.ibm.com> <20180711104618.05dc4b46@gandalf.local.home> <20180711205249.GA32091@joelaf.mtv.corp.google.com> <20180711232120.5dbfa1c7@vmware.local.home> <20180712042825.GA154647@joelaf.mtv.corp.google.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 11 Jul 2018 21:28:25 -0700 Joel Fernandes wrote: > On Wed, Jul 11, 2018 at 11:21:20PM -0400, Steven Rostedt wrote: > > On Wed, 11 Jul 2018 13:52:49 -0700 > > Joel Fernandes wrote: > > > > > > #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ > > > > extern struct tracepoint __tracepoint_##name; \ > > > > static inline void trace_##name(proto) \ > > > > { \ > > > > if (static_key_false(&__tracepoint_##name.key)) \ > > > > __DO_TRACE(&__tracepoint_##name, \ > > > > TP_PROTO(data_proto), \ > > > > TP_ARGS(data_args), \ > > > > TP_CONDITION(cond), 0); \ > > > > if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ > > > > rcu_read_lock_sched_notrace(); \ > > > > rcu_dereference_sched(__tracepoint_##name.funcs);\ > > > > rcu_read_unlock_sched_notrace(); \ > > > > } \ > > > > } > > > > > > > > Because lockdep would only trigger warnings when the tracepoint was > > > > enabled and used in a place it shouldn't be, we added the above > > > > IS_ENABLED(CONFIG_LOCKDEP) part to test regardless if the the > > > > tracepoint was enabled or not. Because we do this, we don't need to > > > > have the test in the __DO_TRACE() code itself. That means we can clean > > > > up the code as per Peter's suggestion. > > > > > > Sounds good, I'm Ok with making this change. > > > > > > Just to clarify, are you proposing to change the rcu_dereference_sched to > > > rcu_dereference_raw in both __DECLARE_TRACE and __DO_TRACE? > > > > No, just in __DO_TRACE(). The rcu_dereference_sched() above in > > __DECLARE_TRACE() in the if (IS_ENABLED(CONFIG_LOCKDEP) block is > > required to show the warnings if trace_##name() is used wrong, and is > > the reason we can use rcu_dereference_raw() in __DO_TRACE() in the > > first place ;-) > > > > This brings up another point. We should probably add to > > __DECLARE_TRACE_RCU() this: > > > > #ifndef MODULE > > #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ > > static inline void trace_##name##_rcuidle(proto) \ > > { \ > > if (static_key_false(&__tracepoint_##name.key)) \ > > __DO_TRACE(&__tracepoint_##name, \ > > TP_PROTO(data_proto), \ > > TP_ARGS(data_args), \ > > TP_CONDITION(cond), 1); \ > > + if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ > > + int idx; \ > > + idx = srcu_read_lock_notrace(&tracepoint_srcu); \ > > + srcu_dereference_notrace(__tracepoint_##name.funcs, \ > > + &tracepoint_srcu); \ > > + srcu_read_unlock_notrace(&tracepoint_srcu, idx); \ > > + } \ > > } > > #else > > > > > > So that lockdep works with trace_##name##__rcuidle() when the trace > > event is not enabled. > > > > But that should be a separate patch and not part of this series. I may > > write that up tomorrow. > > Yes, that sounds good to me and would be good to add the safe guard there. > But you meant srcu_dereference above, not srcu_dereference_notrace right? We don't need to trace them. I believe that the "srcu_*_notrace" still performs the lockdep checks. That's what we want. If they don't then we should not use notrace. But I believe they still do lockdep. -- Steve From mboxrd@z Thu Jan 1 00:00:00 1970 From: rostedt at goodmis.org (Steven Rostedt) Date: Thu, 12 Jul 2018 09:35:12 -0400 Subject: [PATCH v9 4/7] tracepoint: Make rcuidle tracepoint callers use SRCU In-Reply-To: <20180712042825.GA154647@joelaf.mtv.corp.google.com> References: <20180628182149.226164-1-joel@joelfernandes.org> <20180628182149.226164-5-joel@joelfernandes.org> <20180711124954.GE2476@hirez.programming.kicks-ass.net> <20180711090003.42596c2b@gandalf.local.home> <20180711142744.GN3593@linux.vnet.ibm.com> <20180711104618.05dc4b46@gandalf.local.home> <20180711205249.GA32091@joelaf.mtv.corp.google.com> <20180711232120.5dbfa1c7@vmware.local.home> <20180712042825.GA154647@joelaf.mtv.corp.google.com> Message-ID: <20180712093512.1f612a24@gandalf.local.home> On Wed, 11 Jul 2018 21:28:25 -0700 Joel Fernandes wrote: > On Wed, Jul 11, 2018 at 11:21:20PM -0400, Steven Rostedt wrote: > > On Wed, 11 Jul 2018 13:52:49 -0700 > > Joel Fernandes wrote: > > > > > > #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ > > > > extern struct tracepoint __tracepoint_##name; \ > > > > static inline void trace_##name(proto) \ > > > > { \ > > > > if (static_key_false(&__tracepoint_##name.key)) \ > > > > __DO_TRACE(&__tracepoint_##name, \ > > > > TP_PROTO(data_proto), \ > > > > TP_ARGS(data_args), \ > > > > TP_CONDITION(cond), 0); \ > > > > if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ > > > > rcu_read_lock_sched_notrace(); \ > > > > rcu_dereference_sched(__tracepoint_##name.funcs);\ > > > > rcu_read_unlock_sched_notrace(); \ > > > > } \ > > > > } > > > > > > > > Because lockdep would only trigger warnings when the tracepoint was > > > > enabled and used in a place it shouldn't be, we added the above > > > > IS_ENABLED(CONFIG_LOCKDEP) part to test regardless if the the > > > > tracepoint was enabled or not. Because we do this, we don't need to > > > > have the test in the __DO_TRACE() code itself. That means we can clean > > > > up the code as per Peter's suggestion. > > > > > > Sounds good, I'm Ok with making this change. > > > > > > Just to clarify, are you proposing to change the rcu_dereference_sched to > > > rcu_dereference_raw in both __DECLARE_TRACE and __DO_TRACE? > > > > No, just in __DO_TRACE(). The rcu_dereference_sched() above in > > __DECLARE_TRACE() in the if (IS_ENABLED(CONFIG_LOCKDEP) block is > > required to show the warnings if trace_##name() is used wrong, and is > > the reason we can use rcu_dereference_raw() in __DO_TRACE() in the > > first place ;-) > > > > This brings up another point. We should probably add to > > __DECLARE_TRACE_RCU() this: > > > > #ifndef MODULE > > #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ > > static inline void trace_##name##_rcuidle(proto) \ > > { \ > > if (static_key_false(&__tracepoint_##name.key)) \ > > __DO_TRACE(&__tracepoint_##name, \ > > TP_PROTO(data_proto), \ > > TP_ARGS(data_args), \ > > TP_CONDITION(cond), 1); \ > > + if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ > > + int idx; \ > > + idx = srcu_read_lock_notrace(&tracepoint_srcu); \ > > + srcu_dereference_notrace(__tracepoint_##name.funcs, \ > > + &tracepoint_srcu); \ > > + srcu_read_unlock_notrace(&tracepoint_srcu, idx); \ > > + } \ > > } > > #else > > > > > > So that lockdep works with trace_##name##__rcuidle() when the trace > > event is not enabled. > > > > But that should be a separate patch and not part of this series. I may > > write that up tomorrow. > > Yes, that sounds good to me and would be good to add the safe guard there. > But you meant srcu_dereference above, not srcu_dereference_notrace right? We don't need to trace them. I believe that the "srcu_*_notrace" still performs the lockdep checks. That's what we want. If they don't then we should not use notrace. But I believe they still do lockdep. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: rostedt@goodmis.org (Steven Rostedt) Date: Thu, 12 Jul 2018 09:35:12 -0400 Subject: [PATCH v9 4/7] tracepoint: Make rcuidle tracepoint callers use SRCU In-Reply-To: <20180712042825.GA154647@joelaf.mtv.corp.google.com> References: <20180628182149.226164-1-joel@joelfernandes.org> <20180628182149.226164-5-joel@joelfernandes.org> <20180711124954.GE2476@hirez.programming.kicks-ass.net> <20180711090003.42596c2b@gandalf.local.home> <20180711142744.GN3593@linux.vnet.ibm.com> <20180711104618.05dc4b46@gandalf.local.home> <20180711205249.GA32091@joelaf.mtv.corp.google.com> <20180711232120.5dbfa1c7@vmware.local.home> <20180712042825.GA154647@joelaf.mtv.corp.google.com> Message-ID: <20180712093512.1f612a24@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" Message-ID: <20180712133512.CMTPOi-CeOhkwv_moxnVciuZbGA2sRHDtoKP-du7gFA@z> On Wed, 11 Jul 2018 21:28:25 -0700 Joel Fernandes wrote: > On Wed, Jul 11, 2018@11:21:20PM -0400, Steven Rostedt wrote: > > On Wed, 11 Jul 2018 13:52:49 -0700 > > Joel Fernandes wrote: > > > > > > #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ > > > > extern struct tracepoint __tracepoint_##name; \ > > > > static inline void trace_##name(proto) \ > > > > { \ > > > > if (static_key_false(&__tracepoint_##name.key)) \ > > > > __DO_TRACE(&__tracepoint_##name, \ > > > > TP_PROTO(data_proto), \ > > > > TP_ARGS(data_args), \ > > > > TP_CONDITION(cond), 0); \ > > > > if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ > > > > rcu_read_lock_sched_notrace(); \ > > > > rcu_dereference_sched(__tracepoint_##name.funcs);\ > > > > rcu_read_unlock_sched_notrace(); \ > > > > } \ > > > > } > > > > > > > > Because lockdep would only trigger warnings when the tracepoint was > > > > enabled and used in a place it shouldn't be, we added the above > > > > IS_ENABLED(CONFIG_LOCKDEP) part to test regardless if the the > > > > tracepoint was enabled or not. Because we do this, we don't need to > > > > have the test in the __DO_TRACE() code itself. That means we can clean > > > > up the code as per Peter's suggestion. > > > > > > Sounds good, I'm Ok with making this change. > > > > > > Just to clarify, are you proposing to change the rcu_dereference_sched to > > > rcu_dereference_raw in both __DECLARE_TRACE and __DO_TRACE? > > > > No, just in __DO_TRACE(). The rcu_dereference_sched() above in > > __DECLARE_TRACE() in the if (IS_ENABLED(CONFIG_LOCKDEP) block is > > required to show the warnings if trace_##name() is used wrong, and is > > the reason we can use rcu_dereference_raw() in __DO_TRACE() in the > > first place ;-) > > > > This brings up another point. We should probably add to > > __DECLARE_TRACE_RCU() this: > > > > #ifndef MODULE > > #define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ > > static inline void trace_##name##_rcuidle(proto) \ > > { \ > > if (static_key_false(&__tracepoint_##name.key)) \ > > __DO_TRACE(&__tracepoint_##name, \ > > TP_PROTO(data_proto), \ > > TP_ARGS(data_args), \ > > TP_CONDITION(cond), 1); \ > > + if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ > > + int idx; \ > > + idx = srcu_read_lock_notrace(&tracepoint_srcu); \ > > + srcu_dereference_notrace(__tracepoint_##name.funcs, \ > > + &tracepoint_srcu); \ > > + srcu_read_unlock_notrace(&tracepoint_srcu, idx); \ > > + } \ > > } > > #else > > > > > > So that lockdep works with trace_##name##__rcuidle() when the trace > > event is not enabled. > > > > But that should be a separate patch and not part of this series. I may > > write that up tomorrow. > > Yes, that sounds good to me and would be good to add the safe guard there. > But you meant srcu_dereference above, not srcu_dereference_notrace right? We don't need to trace them. I believe that the "srcu_*_notrace" still performs the lockdep checks. That's what we want. If they don't then we should not use notrace. But I believe they still do lockdep. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html