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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 E79BFECE58C for ; Tue, 15 Oct 2019 01:46:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B903021882 for ; Tue, 15 Oct 2019 01:46:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571104018; bh=2zvjhfClW+jLFv0PYyXxNcN6jh1yXpLkZP3XES31WkQ=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=jFURe4v0VuBvZxyt8I7ekaQozxNAapKnCP7cZZ+LKKOf4O2gj9KXEXXJdLOxg0ac8 tRkoRvXq+fX79itz8lN5VHNYGnt3CJvRWPEgPL3iFNM1smsdcRMsr0gcoA6Ss0xp1S 5wgk96vPO7S1+dhxfqA7VxmBZY9Py+K8wXO3gl4k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727474AbfJOBqy (ORCPT ); Mon, 14 Oct 2019 21:46:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:42374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726450AbfJOBqy (ORCPT ); Mon, 14 Oct 2019 21:46:54 -0400 Received: from paulmck-ThinkPad-P72 (unknown [76.14.14.11]) (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 89688217F9; Tue, 15 Oct 2019 01:46:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571104013; bh=2zvjhfClW+jLFv0PYyXxNcN6jh1yXpLkZP3XES31WkQ=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=UMFA9/LdUh1dYx+IBDAozJymR8FuvrK8SdRmpOpPYXayTra4KaUr7I70vZxUMdklT 0gRIFmyDLM0J6Lh4PXBivSNVLKxljDrK6VWYVtj+q7gRMYjL+XJn4SNDHaK8tfhq1b KyRzRj031in/rP1IrpOvqph/JJuu2Oh/YVyZ0C3Q= Date: Mon, 14 Oct 2019 18:46:50 -0700 From: "Paul E. McKenney" To: Joel Fernandes Cc: Lai Jiangshan , 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, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] rcu: make PREEMPT_RCU to be a decoration of TREE_RCU Message-ID: <20191015014650.GL2689@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20191013125959.3280-1-laijs@linux.alibaba.com> <20191014184832.GA125935@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191014184832.GA125935@google.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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. 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 > >