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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 CD7BDC4CECE for ; Mon, 14 Oct 2019 18:48:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A37F5217F9 for ; Mon, 14 Oct 2019 18:48:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="FINe/Hky" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732695AbfJNSsg (ORCPT ); Mon, 14 Oct 2019 14:48:36 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:35913 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731506AbfJNSsg (ORCPT ); Mon, 14 Oct 2019 14:48:36 -0400 Received: by mail-pl1-f196.google.com with SMTP id j11so8386099plk.3 for ; Mon, 14 Oct 2019 11:48:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=sjM15tTgKj3X6UIGIKv9yo7y4Z0++2yHpJVAwICI39U=; b=FINe/HkyYgzCZMpzzJa0VdHcrhwqPEOVm8IYAmsjZctp7jETjAd66xmj9RZqGvrPmj H+FXIhIyR9JSZsKbgRmxWh8p28fI2KaUWsusFrvNmbNdsTSE3WiaTc27SDDPElkItf6I z/5s0o92bcyT34XUr1rDgKnW/+LXvtxg1VAP8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=sjM15tTgKj3X6UIGIKv9yo7y4Z0++2yHpJVAwICI39U=; b=I/GQ3fStV6d1mCHHnGNrJoPEs5bUzRqmGfO2nsIa6wqNrSgEvoUT3li7W88QzJCy4D oyLRq+dYBmzUecdsPSZCOnPCJq5NyMCAQHbLmMAsGuVLhBmtqPj2rAW/4rCsLAAPsczu b7xejpA5rC/ehQXwAVbBxaDUO8BsFdLNTnSSHbhHSyPzQpYXRjEIzAhJ6ATKy6eJ93DH 7+htxajssCeP3B1fqjgKn6iIrcG9XeP19FG7k4+5uA3BbQTx7wOI0DbvGsowuYapHFAS qw3/m5vO5y6wTftL9hUCZNyGSZz7k/L+Esm8mpienTishwSAnEZBzEx6EOjmcEoWx67Q 9Vpw== X-Gm-Message-State: APjAAAV7vSZOOAYyhbNk2VjJfyVND+F07n7uXOj2AGeOL8zJE+o3CvYI IS4SeJsWnR5/YVfVasVtKdCGCA== X-Google-Smtp-Source: APXvYqzR872QIebmrMRQzexybPQBLDCvqPQOvZpwTZP2NY+lIhk2vjsBWna0jd+hGgKFRTdxl/i3zA== X-Received: by 2002:a17:902:aa91:: with SMTP id d17mr30610336plr.69.1571078913729; Mon, 14 Oct 2019 11:48:33 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id j26sm18406495pgl.38.2019.10.14.11.48.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Oct 2019 11:48:33 -0700 (PDT) Date: Mon, 14 Oct 2019 14:48:32 -0400 From: Joel Fernandes To: Lai Jiangshan Cc: Lai Jiangshan , "Paul E. McKenney" , 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: <20191014184832.GA125935@google.com> References: <20191013125959.3280-1-laijs@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191013125959.3280-1-laijs@linux.alibaba.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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) 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 >