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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 69BB4C433E2 for ; Mon, 31 Aug 2020 18:03:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A05A2083E for ; Mon, 31 Aug 2020 18:03:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897021; bh=NnGBpXZSq43kSLTyDI5C4JhFIRLf2MDu2t6S3WvNpMw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=id+xzbp8oGkzXxe6IZZMi3XzXP/mzW9yJTBXL5QCoJ51LlkVbaw11sbrNQCyrJgUZ s8K+GwbkvU4dAw38GK17E5Q719EXjnFKCx3ix8ei5Nksc1iCZL1DvmYOgR0nggLf/a kvTANOEoPO3Val1PZiz+KOP8AEH7B8f16fuvaeas= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729296AbgHaSDk (ORCPT ); Mon, 31 Aug 2020 14:03:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:35926 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728651AbgHaSBX (ORCPT ); Mon, 31 Aug 2020 14:01:23 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 35A4020E65; Mon, 31 Aug 2020 18:01:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598896882; bh=NnGBpXZSq43kSLTyDI5C4JhFIRLf2MDu2t6S3WvNpMw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xoxcJ1hEipPyQBXUNQoix5s52okU3v66/+hDxo/vDOaksDOFWDjAtoNoktp5TOf1l j/YXMwojSX7SHU/RMUhypVUrd1ijYQUYAnnZlhWiKW3aLcD77s4EpCQuceK5rkkbul Swj/ibwBMRo2/EObs9Aj79WyrTuosFm+pStBkHUg= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.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, Neeraj Upadhyay , "Paul E . McKenney" Subject: [PATCH tip/core/rcu 09/24] rcu/tree: Remove CONFIG_PREMPT_RCU check in force_qs_rnp() Date: Mon, 31 Aug 2020 11:01:01 -0700 Message-Id: <20200831180116.32690-9-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831180050.GA32590@paulmck-ThinkPad-P72> References: <20200831180050.GA32590@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Neeraj Upadhyay Originally, the call to rcu_preempt_blocked_readers_cgp() from force_qs_rnp() had to be conditioned on CONFIG_PREEMPT_RCU=y, as in commit a77da14ce9af ("rcu: Yet another fix for preemption and CPU hotplug"). However, there is now a CONFIG_PREEMPT_RCU=n definition of rcu_preempt_blocked_readers_cgp() that unconditionally returns zero, so invoking it is now safe. In addition, the CONFIG_PREEMPT_RCU=n definition of rcu_initiate_boost() simply releases the rcu_node structure's ->lock, which is what happens when the "if" condition evaluates to false. This commit therefore drops the IS_ENABLED(CONFIG_PREEMPT_RCU) check, so that rcu_initiate_boost() is called only in CONFIG_PREEMPT_RCU=y kernels when there are readers blocking the current grace period. This does not change the behavior, but reduces code-reader confusion by eliminating non-CONFIG_PREEMPT_RCU=y calls to rcu_initiate_boost(). Signed-off-by: Neeraj Upadhyay Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 4770d77..acc926f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2533,8 +2533,7 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp)) raw_spin_lock_irqsave_rcu_node(rnp, flags); rcu_state.cbovldnext |= !!rnp->cbovldmask; if (rnp->qsmask == 0) { - if (!IS_ENABLED(CONFIG_PREEMPT_RCU) || - rcu_preempt_blocked_readers_cgp(rnp)) { + if (rcu_preempt_blocked_readers_cgp(rnp)) { /* * No point in scanning bits because they * are all zero. But we might need to -- 2.9.5