From patchwork Wed Oct 19 22:58:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13012480 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 3DFE4C04A95 for ; Wed, 19 Oct 2022 22:59:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230357AbiJSW70 (ORCPT ); Wed, 19 Oct 2022 18:59:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231392AbiJSW65 (ORCPT ); Wed, 19 Oct 2022 18:58:57 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A9821CC762; Wed, 19 Oct 2022 15:58:54 -0700 (PDT) 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 7E0CAB82625; Wed, 19 Oct 2022 22:58:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F2CFC43158; Wed, 19 Oct 2022 22:58:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666220328; bh=q+Nh2vqtEVu5d5wW0RvHG/vkrFq6MOVxBevrDf1eSrY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uN2Y657PIuHGDtEfThRsABBfDWmMY2nPkfEzviDg/z53XUHh45lsuuSSilpTZJSpz 3NHYNYSreQ/zQyMhpaYFRd684T2E8r+C4cuCUGN8buVHW+bgLaKsVO5niw4BheQgfv oI5CKDeCHTWd2QrYmZc51KrYDFFP33b8kAwHeXne1pIAaKFfwlxGCJq7Uzo7gTSBRC lXUSAqY6VVWYmet5AZvswNsazH0XCr6W2/y4lIkcQ/XP8gY6a5SvaeLcOPBmnkRYcq /qOtDVcglyW/+UqM11sLKetAjdUp4xjzvBGSdoE0dPfB32hce9PNR70MKY34hCpHgA t5I0+l6rN+eLw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B781A5C0AC5; Wed, 19 Oct 2022 15:58:47 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, "Paul E. McKenney" , Neeraj Upadhyay , Frederic Weisbecker , Boqun Feng , Huacai Chen , WANG Xuerui , Thomas Gleixner , John Ogness , Petr Mladek , loongarch@lists.linux.dev Subject: [PATCH v3 rcu 07/11] arch/loongarch: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option Date: Wed, 19 Oct 2022 15:58:42 -0700 Message-Id: <20221019225846.2501109-7-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20221019225838.GA2500612@paulmck-ThinkPad-P17-Gen-1> References: <20221019225838.GA2500612@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org The loongarch architecture uses the atomic read-modify-write amadd instruction to implement this_cpu_add(), which is NMI safe. This means that the old and more-efficient srcu_read_lock() may be used in NMI context, without the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/x86/Kconfig, which will cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current srcu_read_lock() behavior. Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ Suggested-by: Neeraj Upadhyay Suggested-by: Frederic Weisbecker Suggested-by: Boqun Feng Signed-off-by: Paul E. McKenney Cc: Huacai Chen Cc: WANG Xuerui Cc: Thomas Gleixner Cc: John Ogness Cc: Petr Mladek Cc: --- arch/loongarch/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 903096bd87f88..386adde2feffb 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -10,6 +10,7 @@ config LOONGARCH select ARCH_ENABLE_MEMORY_HOTPLUG select ARCH_ENABLE_MEMORY_HOTREMOVE select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI + select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_INLINE_READ_LOCK if !PREEMPTION