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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 30CE8C43214 for ; Sun, 15 Aug 2021 21:28:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1485F61373 for ; Sun, 15 Aug 2021 21:28:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231803AbhHOV2a (ORCPT ); Sun, 15 Aug 2021 17:28:30 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:47738 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230124AbhHOV2L (ORCPT ); Sun, 15 Aug 2021 17:28:11 -0400 Message-ID: <20210815211302.088945085@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1629062860; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=q3uXNGa1+gGA4rMhiSsZsQbWYW3cnQwm2UD5Io6f0II=; b=rIarkDDs6cmIBj7NwY7kus6CR3pyG4TsxbzbuyjoOAQZL94D0BIViHrcVJqRXqeiJkLluj E+kR9zlqwy7cqXKTmGZC4Xju7ZGi83fZLSv5ezJLBk3IcZGiKfCXR78q4B3vvcM5FOAtA5 dXbbzBEYO+rP6U0Z1SFayD/Z4sPlxd9/D4wSu6DHoYTIXwkTwAlGaAxDSWY6RblJvz0GQa QJ+m1qFuJ+ABLC1zoT5kx6kXojI8U5ybg2iBiQMiFTAdJLR5xhLrK7Xx8FRBstUTKGtGbV DaCJI94SRfkV605dnkAVtWYQTKs3wMmHs1gN0ukJKOBf2yVDLz2YnTUbiVZhDQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1629062860; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=q3uXNGa1+gGA4rMhiSsZsQbWYW3cnQwm2UD5Io6f0II=; b=ygq/5zqTW4cdFO1xZ3haCi11wG24TRugvouozsEymC1mhSoHkFeGp4vc0dsz0SEKFiRjgu FoWkD+6j8rDiQ+BA== From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Ingo Molnar , Juri Lelli , Steven Rostedt , Daniel Bristot de Oliveira , Will Deacon , Waiman Long , Boqun Feng , Sebastian Andrzej Siewior , Davidlohr Bueso , Mike Galbraith Subject: [patch V5 03/72] sched: Split out the wakeup state check References: <20210815203225.710392609@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit Date: Sun, 15 Aug 2021 23:27:40 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner RT kernels have a slightly more complicated handling of wakeups due to 'sleeping' spin/rwlocks. If a task is blocked on such a lock then the original state of the task is preserved over the blocking and any regular (non lock related) wakeup has to be targeted at the saved state to ensure that these wakeups are not lost. Once the task acquired the lock it restores the task state from the saved state. To avoid cluttering try_to_wake_up() with that logic, split the wake up state check out into an inline helper and use it at both places where task::state is checked against the state argument of try_to_wake_up(). No functional change. Signed-off-by: Thomas Gleixner --- kernel/sched/core.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) --- --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3577,6 +3577,22 @@ static void ttwu_queue(struct task_struc } /* + * Invoked from try_to_wake_up() to check whether the task can be woken up. + * + * The caller holds p::pi_lock if p != current or has preemption + * disabled when p == current. + */ +static __always_inline +bool ttwu_state_match(struct task_struct *p, unsigned int state, int *success) +{ + if (READ_ONCE(p->__state) & state) { + *success = 1; + return true; + } + return false; +} + +/* * Notes on Program-Order guarantees on SMP systems. * * MIGRATION @@ -3715,10 +3731,9 @@ try_to_wake_up(struct task_struct *p, un * - we're serialized against set_special_state() by virtue of * it disabling IRQs (this allows not taking ->pi_lock). */ - if (!(READ_ONCE(p->__state) & state)) + if (!ttwu_state_match(p, state, &success)) goto out; - success = 1; trace_sched_waking(p); WRITE_ONCE(p->__state, TASK_RUNNING); trace_sched_wakeup(p); @@ -3733,14 +3748,11 @@ try_to_wake_up(struct task_struct *p, un */ raw_spin_lock_irqsave(&p->pi_lock, flags); smp_mb__after_spinlock(); - if (!(READ_ONCE(p->__state) & state)) + if (!ttwu_state_match(p, state, &success)) goto unlock; trace_sched_waking(p); - /* We're going to change ->state: */ - success = 1; - /* * Ensure we load p->on_rq _after_ p->state, otherwise it would * be possible to, falsely, observe p->on_rq == 0 and get stuck