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 B83D9C4332F for ; Tue, 22 Mar 2022 13:17:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235296AbiCVNSv (ORCPT ); Tue, 22 Mar 2022 09:18:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235280AbiCVNSs (ORCPT ); Tue, 22 Mar 2022 09:18:48 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BC2885BF2; Tue, 22 Mar 2022 06:17:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647955041; x=1679491041; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=uMUVcf+gEIjrdXadMEnObr5jiYSkzHM/l0NttbKfDx4=; b=AsQbe+Vm61YQ1EK7seYK6Y34B2GNZ9+cnRk3H/o2u5qeGHHOk7Orj0L+ 1bFULHxQ29uZ45UdB5+3otlp5dwO/2q7ibB2d/8IKlPxXUqFvv/jWYyCj x33yDQ0g7lqn22CzmRgsffIrtGnJygoAC7PpOiW1x1f8484jSvdq8SRCQ 159Ndfu25gQO4QIVtC1RscMgv2IFFGtPmtlpjJJttsP3J4K7qTPGKzFzk eiGiztvV6MvHCT3GaQkTtV7LWLiXEyGIusb+bSYrmRFezyohFMECJ03U5 WHcCiIXBz4RTGmw1grSNDFQB9k5dlqgLB5sXQrUNLMB1/ZrUYVitxI2UR A==; X-IronPort-AV: E=McAfee;i="6200,9189,10293"; a="237755609" X-IronPort-AV: E=Sophos;i="5.90,201,1643702400"; d="scan'208";a="237755609" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2022 06:17:20 -0700 X-IronPort-AV: E=Sophos;i="5.90,201,1643702400"; d="scan'208";a="543686441" Received: from zq-optiplex-7090.bj.intel.com ([10.238.156.125]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Mar 2022 06:17:19 -0700 From: Zqiang To: paulmck@kernel.org, frederic@kernel.org Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/2] rcu: Invert the locking dependency order between rcu_state.barrier_mutex and hotplug lock Date: Tue, 22 Mar 2022 21:17:53 +0800 Message-Id: <20220322131753.1680329-3-qiang1.zhang@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220322131753.1680329-1-qiang1.zhang@intel.com> References: <20220322131753.1680329-1-qiang1.zhang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When call rcutree_prepare_cpu(), the cpus write lock has been held, just lock the barrier_mutex before calling rcu_nocb_rdp_deoffload() from failure path. therefore, invert the locking dependency order. Signed-off-by: Zqiang --- kernel/rcu/tree_nocb.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index 154934f3daa9..e3d1bd26d6eb 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1074,8 +1074,8 @@ int rcu_nocb_cpu_deoffload(int cpu) struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); int ret = 0; - mutex_lock(&rcu_state.barrier_mutex); cpus_read_lock(); + mutex_lock(&rcu_state.barrier_mutex); if (rcu_rdp_is_offloaded(rdp)) { if (cpu_online(cpu)) { ret = work_on_cpu(cpu, rcu_nocb_rdp_deoffload, rdp); @@ -1086,8 +1086,8 @@ int rcu_nocb_cpu_deoffload(int cpu) ret = -EINVAL; } } - cpus_read_unlock(); mutex_unlock(&rcu_state.barrier_mutex); + cpus_read_unlock(); return ret; } @@ -1169,8 +1169,8 @@ int rcu_nocb_cpu_offload(int cpu) struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); int ret = 0; - mutex_lock(&rcu_state.barrier_mutex); cpus_read_lock(); + mutex_lock(&rcu_state.barrier_mutex); if (!rcu_rdp_is_offloaded(rdp)) { if (cpu_online(cpu)) { ret = work_on_cpu(cpu, rcu_nocb_rdp_offload, rdp); @@ -1181,8 +1181,8 @@ int rcu_nocb_cpu_offload(int cpu) ret = -EINVAL; } } - cpus_read_unlock(); mutex_unlock(&rcu_state.barrier_mutex); + cpus_read_unlock(); return ret; } -- 2.25.1