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 9903AC7EE36 for ; Sun, 26 Feb 2023 14:45:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229762AbjBZOpF (ORCPT ); Sun, 26 Feb 2023 09:45:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229746AbjBZOpC (ORCPT ); Sun, 26 Feb 2023 09:45:02 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16044126FD; Sun, 26 Feb 2023 06:45:01 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 48409B80BAA; Sun, 26 Feb 2023 14:44:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA7C7C433A1; Sun, 26 Feb 2023 14:44:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677422698; bh=l9FWa21ginmfls4OPysB6O4H3EHsYylnkhLN0FMsqS0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tJffoGL6AccGuG8+l3aqWfVzXeGgjydvxZJqumiFNFGxKSmAo1vGdmanifQK6uw2c 1zpXqJvV3jXp4P0ri6/RSmtvhVmMewU71Y3IpEn80LRl7gD1I7YjI4VSl7WrxcMq0E H67OS6dO6Z5sU0SwynlxPSdXAcI+iov+OQ2IRzoC2IJh7ucS13dw9plspxEAhfqFTq O8d0uCsGETCUOt9/GyQ+lvwQL8xOCPWBS9cM3TydCFFyb+ul34RSPECuZe0oLgpwBu FxEgLJ4pUPXH/ZYjxVCKGkd3eD0tSfxdTQp2QT+V+a6mkpwwJgEkVilRxX6tDMwl6/ 1rEpFA8y85NPA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Paul E. McKenney" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Boqun Feng , Matthew Wilcox , Thomas Gleixner , Sasha Levin , frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, rcu@vger.kernel.org Subject: [PATCH AUTOSEL 6.2 04/53] rcu: Make RCU_LOCKDEP_WARN() avoid early lockdep checks Date: Sun, 26 Feb 2023 09:43:56 -0500 Message-Id: <20230226144446.824580-4-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226144446.824580-1-sashal@kernel.org> References: <20230226144446.824580-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" [ Upstream commit 0cae5ded535c3a80aed94f119bbd4ee3ae284a65 ] Currently, RCU_LOCKDEP_WARN() checks the condition before checking to see if lockdep is still enabled. This is necessary to avoid the false-positive splats fixed by commit 3066820034b5dd ("rcu: Reject RCU_LOCKDEP_WARN() false positives"). However, the current state can result in false-positive splats during early boot before lockdep is fully initialized. This commit therefore checks debug_lockdep_rcu_enabled() both before and after checking the condition, thus avoiding both sets of false-positive error reports. Reported-by: Steven Rostedt Reported-by: Masami Hiramatsu (Google) Reported-by: Mathieu Desnoyers Signed-off-by: Paul E. McKenney Reviewed-by: Mathieu Desnoyers Cc: Boqun Feng Cc: Matthew Wilcox Cc: Thomas Gleixner Signed-off-by: Sasha Levin --- include/linux/rcupdate.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 03abf883a281b..aa86de01aab6d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -374,11 +374,18 @@ static inline int debug_lockdep_rcu_enabled(void) * RCU_LOCKDEP_WARN - emit lockdep splat if specified condition is met * @c: condition to check * @s: informative message + * + * This checks debug_lockdep_rcu_enabled() before checking (c) to + * prevent early boot splats due to lockdep not yet being initialized, + * and rechecks it after checking (c) to prevent false-positive splats + * due to races with lockdep being disabled. See commit 3066820034b5dd + * ("rcu: Reject RCU_LOCKDEP_WARN() false positives") for more detail. */ #define RCU_LOCKDEP_WARN(c, s) \ do { \ static bool __section(".data.unlikely") __warned; \ - if ((c) && debug_lockdep_rcu_enabled() && !__warned) { \ + if (debug_lockdep_rcu_enabled() && (c) && \ + debug_lockdep_rcu_enabled() && !__warned) { \ __warned = true; \ lockdep_rcu_suspicious(__FILE__, __LINE__, s); \ } \ -- 2.39.0