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=-10.1 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,USER_AGENT_GIT 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 E775BC4360C for ; Thu, 3 Oct 2019 01:39:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B14D2222D1 for ; Thu, 3 Oct 2019 01:39:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570066758; bh=R4+8y7N9zQgrqWaJoUYn/0mob3suNOYTLqxQSBYW3A0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iGDWkmLGN0z464BpBdTeyQqJ5cy98LqagEeIBPLufIl1jeccqNW73hypLsrHsq+BQ jSCQ2Vea3Q/gFyKBUROYEQWksSW+HwCydmCidTDjy2MRKfEvZhlthBajbHZyxDz4TO 0mK4Okd6LUivakU1cAubRqbhftfyCgJqt2ndtmgY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728575AbfJCBjL (ORCPT ); Wed, 2 Oct 2019 21:39:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:44818 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727866AbfJCBjH (ORCPT ); Wed, 2 Oct 2019 21:39:07 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D3104222C9; Thu, 3 Oct 2019 01:39:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570066747; bh=R4+8y7N9zQgrqWaJoUYn/0mob3suNOYTLqxQSBYW3A0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HW070pkccYDNcKw7OKYXUyV9GyonGVRezBxdDSvc9hW1pZS+BRJqfoRlsp/2QhxKn YGE0AABiUG0JEjPmybbAI1kBgQpe8LBfvy4xDXMUIzvwGenr1G0AFxs/P6xsOELgdi YqNcIt37xwO35dY87x9BnN+CutmGKyJd8Yr5h5DU= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 05/12] stop_machine: EXP Provide RCU quiescent state in multi_cpu_stop() Date: Wed, 2 Oct 2019 18:38:56 -0700 Message-Id: <20191003013903.13079-5-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20191003013834.GA12927@paulmck-ThinkPad-P72> References: <20191003013834.GA12927@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" When multi_cpu_stop() loops waiting for other tasks, it can trigger an RCU CPU stall warning. This can be misleading because what is instead needed is information on whatever task is blocking multi_cpu_stop(). This commit therefore inserts an RCU quiescent state into the multi_cpu_stop() function's waitloop. Signed-off-by: Paul E. McKenney --- include/linux/rcutree.h | 1 + kernel/rcu/tree.c | 2 +- kernel/stop_machine.c | 1 + 3 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 18b1ed9..c5147de 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -37,6 +37,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func); void rcu_barrier(void); bool rcu_eqs_special_set(int cpu); +void rcu_momentary_dyntick_idle(void); unsigned long get_state_synchronize_rcu(void); void cond_synchronize_rcu(unsigned long oldstate); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index db673ae..f708d54 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -364,7 +364,7 @@ bool rcu_eqs_special_set(int cpu) * * The caller must have disabled interrupts and must not be idle. */ -static void __maybe_unused rcu_momentary_dyntick_idle(void) +void rcu_momentary_dyntick_idle(void) { int special; diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index c7031a2..34c4f11 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -233,6 +233,7 @@ static int multi_cpu_stop(void *data) */ touch_nmi_watchdog(); } + rcu_momentary_dyntick_idle(); } while (curstate != MULTI_STOP_EXIT); local_irq_restore(flags); -- 2.9.5