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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 3B5FAC4CECE for ; Tue, 15 Oct 2019 01:50:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF53421835 for ; Tue, 15 Oct 2019 01:50:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="vQsyyf02" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727528AbfJOBue (ORCPT ); Mon, 14 Oct 2019 21:50:34 -0400 Received: from mail-io1-f65.google.com ([209.85.166.65]:36683 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727524AbfJOBue (ORCPT ); Mon, 14 Oct 2019 21:50:34 -0400 Received: by mail-io1-f65.google.com with SMTP id b136so42277952iof.3; Mon, 14 Oct 2019 18:50:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=o1GMB0sQwNmGsfNZM7UqWz45dZIDAUIhPA3ZbjBqGtI=; b=vQsyyf02EO0FnNh9d538Q/mRuJM9Ue1WndwV1PhNO2wlZ4q2hotCjL1vORz09zQcaW pF8djKcU7HbkbajvqQGGohVvsqzDRM6EDr9iCG1JHAacvG3UQj16ytEBe45QQZTfw7o/ QLlAzQvGOw+cnoRRsM9lWTmqOoUYXwNM4z/iQwIkukBjxeF30iFYLejXF/yDdXZT4ECf 3vF4EzA05Dfld4BVrfOAvxGTQGqGaVBSi1f5D713xcYGqgdIyC/RvHLx6I+NS104tKpv nXapfBFfhemYLbYMr7Rge7nVeN/EmJaqLlzdRdEppOQ+w3ctnbTB2BD4zBbUsy+19Veb Qw3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=o1GMB0sQwNmGsfNZM7UqWz45dZIDAUIhPA3ZbjBqGtI=; b=J7vhy/mvAt/X40OlcFkE5tbZKJ3ZiYmhtub04NOb9VQd3VJztATOUumefCnBAsOpWE jwCa7lwT5tkrfZ/eR+08uLYF4pUbWaGOAbTdBBTr1Kp2RZ23O0ieFd5IKRi9jlU3x2HH OUlX1za3mFc0JctSq7eYuLTkrkkevskVAi46Z9LC+g+IvSa/VXqsDxXXHOo12ApMb5NO SuYIgTMjVH++e/eXw5m63cBMrc6BUUZlxCAtp3dw3rlwHIWnSc8cMm3lpcgKRmUR0Qqe P2Az0B6KcR6+WhK7Uc1+PnUlRD/8nYZCSpJ/qBhI1nBk40QK47MqTTJA/EvXl5f7fMFj oE5Q== X-Gm-Message-State: APjAAAVZHkZIs27ioIUwCAgS8MhHDmpZCdz9T30SeKYpZZy/3GEEopBg JhFN9kfHazcdQ4ZrgZyLnboUup1MNJSj4AI++V0= X-Google-Smtp-Source: APXvYqz+TNcAfzLZNF4xDs6wk0izz0ptDLkUZyRWF+PMFGtXVpQyjOZRlymY96h3gYcaMS8V4sYIVLzSQXdEB20qPBI= X-Received: by 2002:a92:1d5c:: with SMTP id d89mr3461053ild.94.1571104233184; Mon, 14 Oct 2019 18:50:33 -0700 (PDT) MIME-Version: 1.0 References: <20191013125959.3280-1-laijs@linux.alibaba.com> <20191014184832.GA125935@google.com> <20191015014650.GL2689@paulmck-ThinkPad-P72> In-Reply-To: <20191015014650.GL2689@paulmck-ThinkPad-P72> From: Lai Jiangshan Date: Tue, 15 Oct 2019 09:50:21 +0800 Message-ID: Subject: Re: [PATCH] rcu: make PREEMPT_RCU to be a decoration of TREE_RCU To: paulmck@kernel.org Cc: Joel Fernandes , Lai Jiangshan , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Ingo Molnar , Luis Chamberlain , Kees Cook , David Sterba , Yafang Shao , Mike Rapoport , Petr Mladek , Sakari Ailus , rcu@vger.kernel.org, LKML , Linux FS Devel Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Oct 15, 2019 at 9:46 AM Paul E. McKenney wrote: > > On Mon, Oct 14, 2019 at 02:48:32PM -0400, Joel Fernandes wrote: > > On Sun, Oct 13, 2019 at 12:59:57PM +0000, Lai Jiangshan wrote: > > > Currently PREEMPT_RCU and TREE_RCU are "contrary" configs > > > when they can't be both on. But PREEMPT_RCU is actually a kind > > > of TREE_RCU in the implementation. It seams to be appropriate > > > to make PREEMPT_RCU to be a decorative option of TREE_RCU. > > > > > > > Looks like a nice simplification and so far I could not poke any holes in the > > code... > > > > I am in support of this patch for further review and testing. Thanks! > > > > Reviewed-by: Joel Fernandes (Google) > > Thank you both! > > Lai, what is this patch against? It does not want to apply to the current > -rcu "dev" branch. Oh, sorry I wrongly made the change base on upstream. I will rebase later. thanks Lai > > Thanx, Paul > > > thanks, > > > > - Joel > > > > > > > Signed-off-by: Lai Jiangshan > > > Signed-off-by: Lai Jiangshan > > > --- > > > include/linux/rcupdate.h | 4 ++-- > > > include/trace/events/rcu.h | 4 ++-- > > > kernel/rcu/Kconfig | 13 +++++++------ > > > kernel/rcu/Makefile | 1 - > > > kernel/rcu/rcu.h | 2 +- > > > kernel/rcu/update.c | 2 +- > > > kernel/sysctl.c | 2 +- > > > 7 files changed, 14 insertions(+), 14 deletions(-) > > > > > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > > > index 75a2eded7aa2..1eee9f6c27f9 100644 > > > --- a/include/linux/rcupdate.h > > > +++ b/include/linux/rcupdate.h > > > @@ -167,7 +167,7 @@ do { \ > > > * TREE_RCU and rcu_barrier_() primitives in TINY_RCU. > > > */ > > > > > > -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) > > > +#if defined(CONFIG_TREE_RCU) > > > #include > > > #elif defined(CONFIG_TINY_RCU) > > > #include > > > @@ -583,7 +583,7 @@ do { \ > > > * read-side critical section that would block in a !PREEMPT kernel. > > > * But if you want the full story, read on! > > > * > > > - * In non-preemptible RCU implementations (TREE_RCU and TINY_RCU), > > > + * In non-preemptible RCU implementations (pure TREE_RCU and TINY_RCU), > > > * it is illegal to block while in an RCU read-side critical section. > > > * In preemptible RCU implementations (PREEMPT_RCU) in CONFIG_PREEMPTION > > > * kernel builds, RCU read-side critical sections may be preempted, > > > diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h > > > index 694bd040cf51..1ce15c5be4c8 100644 > > > --- a/include/trace/events/rcu.h > > > +++ b/include/trace/events/rcu.h > > > @@ -41,7 +41,7 @@ TRACE_EVENT(rcu_utilization, > > > TP_printk("%s", __entry->s) > > > ); > > > > > > -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) > > > +#if defined(CONFIG_TREE_RCU) > > > > > > /* > > > * Tracepoint for grace-period events. Takes a string identifying the > > > @@ -425,7 +425,7 @@ TRACE_EVENT_RCU(rcu_fqs, > > > __entry->cpu, __entry->qsevent) > > > ); > > > > > > -#endif /* #if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) */ > > > +#endif /* #if defined(CONFIG_TREE_RCU) */ > > > > > > /* > > > * Tracepoint for dyntick-idle entry/exit events. These take a string > > > diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig > > > index 7644eda17d62..0303934e6ef0 100644 > > > --- a/kernel/rcu/Kconfig > > > +++ b/kernel/rcu/Kconfig > > > @@ -7,7 +7,7 @@ menu "RCU Subsystem" > > > > > > config TREE_RCU > > > bool > > > - default y if !PREEMPTION && SMP > > > + default y if SMP > > > help > > > This option selects the RCU implementation that is > > > designed for very large SMP system with hundreds or > > > @@ -17,6 +17,7 @@ config TREE_RCU > > > config PREEMPT_RCU > > > bool > > > default y if PREEMPTION > > > + select TREE_RCU > > > help > > > This option selects the RCU implementation that is > > > designed for very large SMP systems with hundreds or > > > @@ -78,7 +79,7 @@ config TASKS_RCU > > > user-mode execution as quiescent states. > > > > > > config RCU_STALL_COMMON > > > - def_bool ( TREE_RCU || PREEMPT_RCU ) > > > + def_bool TREE_RCU > > > help > > > This option enables RCU CPU stall code that is common between > > > the TINY and TREE variants of RCU. The purpose is to allow > > > @@ -86,13 +87,13 @@ config RCU_STALL_COMMON > > > making these warnings mandatory for the tree variants. > > > > > > config RCU_NEED_SEGCBLIST > > > - def_bool ( TREE_RCU || PREEMPT_RCU || TREE_SRCU ) > > > + def_bool ( TREE_RCU || TREE_SRCU ) > > > > > > config RCU_FANOUT > > > int "Tree-based hierarchical RCU fanout value" > > > range 2 64 if 64BIT > > > range 2 32 if !64BIT > > > - depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT > > > + depends on TREE_RCU && RCU_EXPERT > > > default 64 if 64BIT > > > default 32 if !64BIT > > > help > > > @@ -112,7 +113,7 @@ config RCU_FANOUT_LEAF > > > int "Tree-based hierarchical RCU leaf-level fanout value" > > > range 2 64 if 64BIT > > > range 2 32 if !64BIT > > > - depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT > > > + depends on TREE_RCU && RCU_EXPERT > > > default 16 > > > help > > > This option controls the leaf-level fanout of hierarchical > > > @@ -187,7 +188,7 @@ config RCU_BOOST_DELAY > > > > > > config RCU_NOCB_CPU > > > bool "Offload RCU callback processing from boot-selected CPUs" > > > - depends on TREE_RCU || PREEMPT_RCU > > > + depends on TREE_RCU > > > depends on RCU_EXPERT || NO_HZ_FULL > > > default n > > > help > > > diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile > > > index 020e8b6a644b..82d5fba48b2f 100644 > > > --- a/kernel/rcu/Makefile > > > +++ b/kernel/rcu/Makefile > > > @@ -9,6 +9,5 @@ obj-$(CONFIG_TINY_SRCU) += srcutiny.o > > > obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o > > > obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o > > > obj-$(CONFIG_TREE_RCU) += tree.o > > > -obj-$(CONFIG_PREEMPT_RCU) += tree.o > > > obj-$(CONFIG_TINY_RCU) += tiny.o > > > obj-$(CONFIG_RCU_NEED_SEGCBLIST) += rcu_segcblist.o > > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > > > index 8fd4f82c9b3d..4149ba76824f 100644 > > > --- a/kernel/rcu/rcu.h > > > +++ b/kernel/rcu/rcu.h > > > @@ -452,7 +452,7 @@ enum rcutorture_type { > > > INVALID_RCU_FLAVOR > > > }; > > > > > > -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) > > > +#if defined(CONFIG_TREE_RCU) > > > void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, > > > unsigned long *gp_seq); > > > void rcutorture_record_progress(unsigned long vernum); > > > diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c > > > index 1861103662db..34a7452b25fd 100644 > > > --- a/kernel/rcu/update.c > > > +++ b/kernel/rcu/update.c > > > @@ -435,7 +435,7 @@ struct debug_obj_descr rcuhead_debug_descr = { > > > EXPORT_SYMBOL_GPL(rcuhead_debug_descr); > > > #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ > > > > > > -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE) > > > +#if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE) > > > void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, > > > unsigned long secs, > > > unsigned long c_old, unsigned long c) > > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > > > index 00fcea236eba..2ace158a4d72 100644 > > > --- a/kernel/sysctl.c > > > +++ b/kernel/sysctl.c > > > @@ -1268,7 +1268,7 @@ static struct ctl_table kern_table[] = { > > > .proc_handler = proc_do_static_key, > > > }, > > > #endif > > > -#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) > > > +#if defined(CONFIG_TREE_RCU) > > > { > > > .procname = "panic_on_rcu_stall", > > > .data = &sysctl_panic_on_rcu_stall, > > > -- > > > 2.20.1 > > >