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,URIBL_BLOCKED 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 44EF2C432BE for ; Wed, 11 Aug 2021 12:24:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 270BC6101D for ; Wed, 11 Aug 2021 12:24:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238295AbhHKMZI (ORCPT ); Wed, 11 Aug 2021 08:25:08 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:50490 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237716AbhHKMXV (ORCPT ); Wed, 11 Aug 2021 08:23:21 -0400 Message-ID: <20210811121415.403149201@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1628684576; 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=+YnMRjsnxk84Or/H+2smifp2SyRHTm7IycMX/nyQ9U0=; b=TsO4JhqrNlsL4MUYiCt3CA5XnD8n74sOfKmp5/ECXE9oy6BmWlDTjli+ogccXlxGAwilT8 pxQeK227/q473wp/bF3yHUFqplTk3rOtsJI+FuLPtNGB053ZCWYMONfEoWNa8Ox+q7QLa7 Hqi5tgxS0JPgclIEcAEg17Ut9DGaXvErsvUZ7eCjxv8CoOUVBY4V6gBQlwEYUbYRgRlPWa /0ujDo0mhVuCAjw4s5abEiRS2M+y5mvCzMwuOfNypNvYcny7wgEAd5deJ81PY2PSM6GPbT K50V9s8dt5qZaTZj5rA7Q7qtNRlS2c8FuKMdd+CEfiGKSHlp/SpZzaqfFI/eIw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1628684576; 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=+YnMRjsnxk84Or/H+2smifp2SyRHTm7IycMX/nyQ9U0=; b=eO4Yterc9XzVBiobmi+pJtXtV/xMsDJE4Pe87Ef7p48WoeDrHiciUADnO/L+u9x/+41kse dyC2IOAn22qLpEAQ== 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 V4 21/68] locking/rtmutex: Prepare RT rt_mutex_wake_q for RT locks References: <20210811120348.855823694@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit Date: Wed, 11 Aug 2021 14:22:56 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner Add a rtlock_task pointer to rt_mutex_wake_q which allows to handle the RT specific wakeup for spin/rwlock waiters. The pointer is just consuming 4/8 bytes on stack so it is provided unconditionaly to avoid #ifdeffery all over the place. This cannot use a wake_q because a task can have concurrent wakeups which would make it miss either lock or the regular wakeup depending on what gets queued first unless task struct gains a separate wake_q_node for this which would be overkill because there can only be a single task which gets woken up in the spin/rw_lock unlock path. No functional change for non-RT enabled kernels. Signed-off-by: Thomas Gleixner --- V3: Switch back to the working version (Mike) V2: Make it symmetric (PeterZ) --- include/linux/sched/wake_q.h | 1 - kernel/locking/rtmutex.c | 18 ++++++++++++++++-- kernel/locking/rtmutex_common.h | 5 ++++- 3 files changed, 20 insertions(+), 4 deletions(-) --- --- a/include/linux/sched/wake_q.h +++ b/include/linux/sched/wake_q.h @@ -62,5 +62,4 @@ static inline bool wake_q_empty(struct w extern void wake_q_add(struct wake_q_head *head, struct task_struct *task); extern void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task); extern void wake_up_q(struct wake_q_head *head); - #endif /* _LINUX_SCHED_WAKE_Q_H */ --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -351,12 +351,26 @@ static __always_inline void rt_mutex_adj static __always_inline void rt_mutex_wake_q_add(struct rt_wake_q_head *wqh, struct rt_mutex_waiter *w) { - wake_q_add(&wqh->head, w->task); + if (IS_ENABLED(CONFIG_PREEMPT_RT) && w->wake_state != TASK_NORMAL) { + if (IS_ENABLED(CONFIG_PROVE_LOCKING)) + WARN_ON_ONCE(wqh->rtlock_task); + get_task_struct(w->task); + wqh->rtlock_task = w->task; + } else { + wake_q_add(&wqh->head, w->task); + } } static __always_inline void rt_mutex_wake_up_q(struct rt_wake_q_head *wqh) { - wake_up_q(&wqh->head); + if (IS_ENABLED(CONFIG_PREEMPT_RT) && wqh->rtlock_task) { + wake_up_state(wqh->rtlock_task, TASK_RTLOCK_WAIT); + put_task_struct(wqh->rtlock_task); + wqh->rtlock_task = NULL; + } + + if (!wake_q_empty(&wqh->head)) + wake_up_q(&wqh->head); /* Pairs with preempt_disable() in mark_wakeup_next_waiter() */ preempt_enable(); --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -42,15 +42,18 @@ struct rt_mutex_waiter { /** * rt_wake_q_head - Wrapper around regular wake_q_head to support * "sleeping" spinlocks on RT - * @head: The regular wake_q_head for sleeping lock variants + * @head: The regular wake_q_head for sleeping lock variants + * @rtlock_task: Task pointer for RT lock (spin/rwlock) wakeups */ struct rt_wake_q_head { struct wake_q_head head; + struct task_struct *rtlock_task; }; #define DEFINE_RT_WAKE_Q(name) \ struct rt_wake_q_head name = { \ .head = WAKE_Q_HEAD_INITIALIZER(name.head), \ + .rtlock_task = NULL, \ } /*