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=-19.7 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=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 3501CC433B4 for ; Tue, 11 May 2021 23:07:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1CE0561625 for ; Tue, 11 May 2021 23:07:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230075AbhEKXJB (ORCPT ); Tue, 11 May 2021 19:09:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:45554 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229848AbhEKXIz (ORCPT ); Tue, 11 May 2021 19:08:55 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3DF8B61919; Tue, 11 May 2021 23:07:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620774468; bh=JKlIzbvIU/cyHISlHCUNpKgOKDgTFohESIuAMUdNs7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eR53HZN56IwaRXE07Vs/hPxYXn7xexFHdrk+Pj1hUoLHq//GoxlWtmzOLmx3oxKzJ CDf9QsRIpdsv4KLevbXVcVONdna8g1sYKHTtElEqPfnV1EjqMNrvIFB14K6eG9ARR3 q5mleMOvhg7fID+eTqF6BhGso9bWTB979OSoLQgHlLsnb9oYSBRxeluJN+NPGw0aVE /hChzgtgV3ntfxPF8zqbujNRMPvuA8ZlKl7sUVjRBFudPFza6XQQTb1H5I6+xKdei5 GbK3IpfETbJ6G+fmKrrF27XsD4AZrwnR/q5WOATvNuQ28s3LJ+gqnC/NmFX7YuA3VI E1uE5ojMwVfEA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id E0D535C0B55; Tue, 11 May 2021 16:07:47 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.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, Frederic Weisbecker , Uladzislau Rezki , Boqun Feng , Neeraj Upadhyay , "Paul E . McKenney" Subject: [PATCH tip/core/rcu 4/6] srcu: Initialize SRCU after timers Date: Tue, 11 May 2021 16:07:43 -0700 Message-Id: <20210511230745.2894650-4-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210511230720.GA2894512@paulmck-ThinkPad-P17-Gen-1> References: <20210511230720.GA2894512@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Frederic Weisbecker Once srcu_init() is called, the SRCU core will make use of delayed workqueues, which rely on timers. However init_timers() is called several steps after rcu_init(). This means that a call_srcu() after rcu_init() but before init_timers() would find itself within a dangerously uninitialized timer core. This commit therefore creates a separate call to srcu_init() after init_timer() completes, which ensures that we stay in early SRCU mode until timers are safe(r). Signed-off-by: Frederic Weisbecker Cc: Uladzislau Rezki Cc: Boqun Feng Cc: Lai Jiangshan Cc: Neeraj Upadhyay Cc: Josh Triplett Cc: Joel Fernandes Signed-off-by: Paul E. McKenney --- 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 eb01e121d2f1..7b6f49c4d388 100644 --- a/init/main.c +++ b/init/main.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include #include @@ -979,6 +980,7 @@ 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 bf0827d4b659..ca3f2af32bf8 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 f4f0cbf7a02b..9ec35c158740 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 8e78b2430c16..c35b15229cff 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4735,7 +4735,6 @@ 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! */ -- 2.31.1.189.g2e36527f23