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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=ham 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 67913C432BE for ; Wed, 1 Sep 2021 22:29:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39E3B61075 for ; Wed, 1 Sep 2021 22:29:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240694AbhIAWaX (ORCPT ); Wed, 1 Sep 2021 18:30:23 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:39638 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230059AbhIAWaW (ORCPT ); Wed, 1 Sep 2021 18:30:22 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id C48452251F; Wed, 1 Sep 2021 22:29:23 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id D2D8A13B03; Wed, 1 Sep 2021 22:29:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id VhRiJ8D+L2FiJgAAMHmgww (envelope-from ); Wed, 01 Sep 2021 22:29:20 +0000 From: Davidlohr Bueso To: tglx@linutronix.de Cc: peterz@infradead.org, mingo@kernel.org, rostedt@goodmis.org, longman@redhat.com, bigeasy@linutronix.de, boqun.feng@gmail.com, dave@stgolabs.net, linux-kernel@vger.kernel.org Subject: [PATCH 0/2] locking/rwbase_rt: Use wake_q for lockless reader waker Date: Wed, 1 Sep 2021 15:28:23 -0700 Message-Id: <20210901222825.6313-1-dave@stgolabs.net> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Patch 1 does some necessary code reordering. Patch 2 introduces wake_up_q_state() and converts rwbase_read_unlock() slowpath to use wake_q instead of holding the wait_lock across the entire wakeup. I have tested equivalent changes in the preempt_rt kernel (v5.14.y-rt) stressing mmap_sem, without anything falling out. Thanks! Davidlohr Bueso (2): sched: Move wake_q code below try_to_wake_up() locking/rwbase_rt: Lockless reader waking up a writer kernel/locking/rwbase_rt.c | 4 +- kernel/sched/core.c | 182 +++++++++++++++++++------------------ 2 files changed, 99 insertions(+), 87 deletions(-) -- 2.26.2