From patchwork Fri Oct 23 14:46:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederic Weisbecker X-Patchwork-Id: 1323999 Return-Path: Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CAC57C4363A for ; Fri, 23 Oct 2020 14:48:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7029620853 for ; Fri, 23 Oct 2020 14:48:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603464501; bh=4nDVa8AWwZ+W9cuyfOQDOCLr65TDab1p9NGvByeim7c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=s2oLtdrA4glAcE4nVG8WHR6oFQ6b7+vAFQ5/OhlYNHXwSd7Y84pKKldOwV3YTmo62 oOkbLqN8Jyg806qm2Sj5Hn9x9Myp8pJfP2zZ/xv+oKcFPjGAWqTijkV3tdc4Oplkxa lFW1kDGKXdJE9UmhYnqRVD3ZYass2qzfEO8+Qooc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750735AbgJWOsU (ORCPT ); Fri, 23 Oct 2020 10:48:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:33542 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750780AbgJWOrc (ORCPT ); Fri, 23 Oct 2020 10:47:32 -0400 Received: from localhost.localdomain (unknown [176.167.163.208]) (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 A755C22254; Fri, 23 Oct 2020 14:47:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603464451; bh=4nDVa8AWwZ+W9cuyfOQDOCLr65TDab1p9NGvByeim7c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wE+CoSVcT1zXnOr+FweFDGskNVo60+LKg1nnxtjBAWU/WXEVZ6PnQqq7ytY5nqHsS hh3xiwsQuPxM85TYSggeZ1yz+hqagTpxpXDef0n0Jq0hieoFuBLee80RQB3OnaokT7 0hkth8s22C0OJakV31UYhNebuPTaaE9PpqBu+w3M= From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Steven Rostedt , Mathieu Desnoyers , "Paul E . McKenney" , Lai Jiangshan , Neeraj Upadhyay , Joel Fernandes , Josh Triplett Subject: [PATCH 14/16] rcu: Locally accelerate callbacks as long as offloading isn't complete Date: Fri, 23 Oct 2020 16:46:47 +0200 Message-Id: <20201023144649.53046-15-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201023144649.53046-1-frederic@kernel.org> References: <20201023144649.53046-1-frederic@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The local callbacks processing checks if some callbacks need acceleration. Keep that behaviour under nocb lock protection when rcu_core() executes concurrently with GP/CB kthreads. Inspired-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes Cc: Neeraj Upadhyay --- kernel/rcu/tree.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 45fad6977bea..4af5fed11885 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2673,7 +2673,6 @@ static __latent_entropy void rcu_core(void) unsigned long flags; struct rcu_data *rdp = raw_cpu_ptr(&rcu_data); struct rcu_node *rnp = rdp->mynode; - const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist); const bool do_batch = !rcu_segcblist_completely_offloaded(&rdp->cblist); if (cpu_is_offline(smp_processor_id())) @@ -2694,11 +2693,11 @@ static __latent_entropy void rcu_core(void) /* No grace period and unregistered callbacks? */ if (!rcu_gp_in_progress() && - rcu_segcblist_is_enabled(&rdp->cblist) && !offloaded) { - local_irq_save(flags); + rcu_segcblist_is_enabled(&rdp->cblist) && do_batch) { + rcu_nocb_lock_irqsave(rdp, flags); if (!rcu_segcblist_restempty(&rdp->cblist, RCU_NEXT_READY_TAIL)) rcu_accelerate_cbs_unlocked(rnp, rdp); - local_irq_restore(flags); + rcu_nocb_unlock_irqrestore(rdp, flags); } rcu_check_gp_start_stall(rnp, rdp, rcu_jiffies_till_stall_check());