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 D815EC433F5 for ; Sat, 12 Mar 2022 23:23:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232950AbiCLXYp (ORCPT ); Sat, 12 Mar 2022 18:24:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231277AbiCLXYn (ORCPT ); Sat, 12 Mar 2022 18:24:43 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C8877004D for ; Sat, 12 Mar 2022 15:23:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=cPW9deNLTzJWDGiUMvxcRKPakWis975fOAZjzHmtJjs=; b=sHfzDbA6HYM1b0aKSrN9SL9J7x cdE0uPCWLjbTJFkblGUiL1z8H4Pj8KMem/FbEEQfU9wBbSBoqToZpqdNDQHB5nD8cgSb9x5Qgy+OB QjjH5XB9L1Ia1gk31c0hTjx5FVlpQiElSBtDEFvFh4V4a7JKGQ5YCK4mx1tJ/QOZoSiDA/264sUKh aYLrlWo0Vn7/cqoDvInfdQO2IO7IEqjF9+x8SySXXlI7seTUoArSQbPzWoPG6D17Udajsn6rQZgKL hwRaUZtM6JLn68YOQgdrI7L59pZrFFmo5bPUnPl4fc1YeAMHk0YsPX9GnuKiiok02q0EnzZCn4rVv DBguaadg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nTB4n-002m28-6U; Sat, 12 Mar 2022 23:23:09 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 53A30987D0D; Sun, 13 Mar 2022 00:23:07 +0100 (CET) Date: Sun, 13 Mar 2022 00:23:07 +0100 From: Peter Zijlstra To: Frederic Weisbecker Cc: LKML , Phil Auld , Alex Belits , Nicolas Saenz Julienne , Xiongfeng Wang , Neeraj Upadhyay , Thomas Gleixner , Yu Liao , Boqun Feng , "Paul E . McKenney" , Marcelo Tosatti , Paul Gortmaker , Uladzislau Rezki , Joel Fernandes Subject: Re: [PATCH 11/19] rcu/context_tracking: Move dynticks_nesting to context tracking Message-ID: <20220312232307.GJ28057@worktop.programming.kicks-ass.net> References: <20220302154810.42308-1-frederic@kernel.org> <20220302154810.42308-12-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220302154810.42308-12-frederic@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 02, 2022 at 04:48:02PM +0100, Frederic Weisbecker wrote: > @@ -441,7 +440,7 @@ static int rcu_is_cpu_rrupt_from_idle(void) > lockdep_assert_irqs_disabled(); > > /* Check for counter underflows */ > - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) < 0, > + RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nesting) < 0, > "RCU dynticks_nesting counter underflow!"); > RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 0, > "RCU dynticks_nmi_nesting counter underflow/zero!"); > @@ -457,7 +456,7 @@ static int rcu_is_cpu_rrupt_from_idle(void) > WARN_ON_ONCE(!nesting && !is_idle_task(current)); > > /* Does CPU appear to be idle from an RCU standpoint? */ > - return __this_cpu_read(rcu_data.dynticks_nesting) == 0; > + return __this_cpu_read(context_tracking.dynticks_nesting) == 0; > } > > #define DEFAULT_RCU_BLIMIT (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 1000 : 10) > @@ -798,7 +797,7 @@ void rcu_irq_exit_check_preempt(void) > { > lockdep_assert_irqs_disabled(); > > - RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0, > + RCU_LOCKDEP_WARN(__this_cpu_read(context_tracking.dynticks_nesting) <= 0, > "RCU dynticks_nesting counter underflow/zero!"); > RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) != > DYNTICK_IRQ_NONIDLE, Would it make sense to create __ct_wrappers() to access the dynticks_{nmi_,}_nesting counters ? > @@ -4122,12 +4121,13 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf) > static void __init > rcu_boot_init_percpu_data(int cpu) > { > + struct context_tracking *ct = this_cpu_ptr(&context_tracking); > struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); > > /* Set up local state, ensuring consistent view of global state. */ > rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu); > INIT_WORK(&rdp->strict_work, strict_work_handler); > - WARN_ON_ONCE(rdp->dynticks_nesting != 1); > + WARN_ON_ONCE(ct->dynticks_nesting != 1); > WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu))); > rdp->barrier_seq_snap = rcu_state.barrier_sequence; > rdp->rcu_ofl_gp_seq = rcu_state.gp_seq; > @@ -4152,6 +4152,7 @@ rcu_boot_init_percpu_data(int cpu) > int rcutree_prepare_cpu(unsigned int cpu) > { > unsigned long flags; > + struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu); > struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); > struct rcu_node *rnp = rcu_get_root(); > > diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h > index 202129b1c7e4..30a5e0a8ddb3 100644 > --- a/kernel/rcu/tree_stall.h > +++ b/kernel/rcu/tree_stall.h > @@ -429,6 +429,7 @@ static void print_cpu_stall_info(int cpu) > { > unsigned long delta; > bool falsepositive; > + struct context_tracking *ct = this_cpu_ptr(&context_tracking); > struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); > char *ticks_title; > unsigned long ticks_value; > @@ -459,7 +460,7 @@ static void print_cpu_stall_info(int cpu) > "!."[!delta], > ticks_value, ticks_title, > rcu_dynticks_snap(cpu) & 0xfff, > - rdp->dynticks_nesting, rdp->dynticks_nmi_nesting, > + ct->dynticks_nesting, rdp->dynticks_nmi_nesting, > rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), > data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, > falsepositive ? " (false positive?)" : ""); And perhaps helpers here too? RCU grubbing in the context_tracking internals seems a bit yuck.