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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 32C3DC433ED for ; Thu, 8 Apr 2021 22:39:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF11F61159 for ; Thu, 8 Apr 2021 22:39:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232866AbhDHWj1 (ORCPT ); Thu, 8 Apr 2021 18:39:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:48108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232834AbhDHWjY (ORCPT ); Thu, 8 Apr 2021 18:39:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8B7A361106; Thu, 8 Apr 2021 22:39:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617921552; bh=/8lOvv02fbJoqAABTAzMdRSZlGS0NO/Q+ZmhS6o46SI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nT27ewTW6Ph+2/gZtTNfaimWbfZnPLkF/BKwFATkdkPjBkyFzVaDUfnsL50cuSAoE FTEoNyPJw+XwFRB6GDfuFa62+Sm5oufWbqlWMvmhsZDcGZjqcorz8Vy7eur0esuLoG 7j9Cs7Ga/Fd9ZADjEGj5h2J/a4xWtGEbCkrxm4NaY5mbxv3GjCiB453wH2QXVO53T3 VPzmz78lAJAvFXOC1ipgX/1vt6qLPq9YhOO99vFkOVe3ejkslVmlt+3gHIGHpAOE10 NatcRKvFtH4xhGYcmx+pd3SI7bD7r6Mq8Xj85IAQbpe6uErLCEm2zBL3BzP4XCwZHp s3+F7ov8ChylA== From: Frederic Weisbecker To: "Paul E . McKenney" Cc: LKML , Frederic Weisbecker , Uladzislau Rezki , Boqun Feng , Lai Jiangshan , Neeraj Upadhyay , Josh Triplett , Joel Fernandes Subject: [PATCH 2/5] srcu: Initialize SRCU after timers Date: Fri, 9 Apr 2021 00:38:59 +0200 Message-Id: <20210408223902.6405-3-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210408223902.6405-1-frederic@kernel.org> References: <20210408223902.6405-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Once srcu_init() is called, the SRCU core is free to queue delayed workqueues, which rely on timers. However init_timers() is called several steps after rcu_init(). Any call_srcu() in-between would finish its course inside a dangerously uninitialized timer core. Make sure we stay in early SRCU mode until everything is well settled. Signed-off-by: Frederic Weisbecker Cc: Uladzislau Rezki Cc: Boqun Feng Cc: Lai Jiangshan Cc: Neeraj Upadhyay Cc: Josh Triplett Cc: Joel Fernandes --- include/linux/srcu.h | 6 ++++++ init/main.c | 2 ++ kernel/rcu/rcu.h | 6 ------ kernel/rcu/srcutree.c | 5 +++++ kernel/rcu/tiny.c | 1 - kernel/rcu/tree.c | 1 - 6 files changed, 13 insertions(+), 8 deletions(-) diff --git a/include/linux/srcu.h b/include/linux/srcu.h index a0895bbf71ce..e6011a9975af 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -64,6 +64,12 @@ unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp); unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp); bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie); +#ifdef CONFIG_SRCU +void srcu_init(void); +#else /* #ifdef CONFIG_SRCU */ +static inline void srcu_init(void) { } +#endif /* #else #ifdef CONFIG_SRCU */ + #ifdef CONFIG_DEBUG_LOCK_ALLOC /** diff --git a/init/main.c b/init/main.c index 53b278845b88..1bc5cc9e52ef 100644 --- a/init/main.c +++ b/init/main.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include #include @@ -956,6 +957,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) tick_init(); rcu_init_nohz(); init_timers(); + srcu_init(); hrtimers_init(); softirq_init(); timekeeping_init(); diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index d64b842f4078..b3af34068051 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -422,12 +422,6 @@ do { \ #endif /* #if defined(CONFIG_SRCU) || !defined(CONFIG_TINY_RCU) */ -#ifdef CONFIG_SRCU -void srcu_init(void); -#else /* #ifdef CONFIG_SRCU */ -static inline void srcu_init(void) { } -#endif /* #else #ifdef CONFIG_SRCU */ - #ifdef CONFIG_TINY_RCU /* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */ static inline bool rcu_gp_is_normal(void) { return true; } diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 10e681ea7051..108f9ca06047 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1384,6 +1384,11 @@ void __init srcu_init(void) { struct srcu_struct *ssp; + /* + * Once that is set, call_srcu() can follow the normal path and + * queue delayed work. This must follow RCU workqueues creation + * and timers initialization. + */ srcu_init_done = true; while (!list_empty(&srcu_boot_list)) { ssp = list_first_entry(&srcu_boot_list, struct srcu_struct, diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c index c8a029fbb114..340b3f8b090d 100644 --- a/kernel/rcu/tiny.c +++ b/kernel/rcu/tiny.c @@ -221,5 +221,4 @@ void __init rcu_init(void) { open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); rcu_early_boot_tests(); - srcu_init(); } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5c214705c33f..740f5cd34459 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4714,7 +4714,6 @@ void __init rcu_init(void) WARN_ON(!rcu_gp_wq); rcu_par_gp_wq = alloc_workqueue("rcu_par_gp", WQ_MEM_RECLAIM, 0); WARN_ON(!rcu_par_gp_wq); - srcu_init(); /* Fill in default value for rcutree.qovld boot parameter. */ /* -After- the rcu_node ->lock fields are initialized! */ -- 2.25.1