From patchwork Thu Aug 13 01:45:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 257107 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=-10.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS 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 21E89C433DF for ; Thu, 13 Aug 2020 01:46:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 055162184D for ; Thu, 13 Aug 2020 01:46:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726656AbgHMBqC (ORCPT ); Wed, 12 Aug 2020 21:46:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:33076 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726518AbgHMBp5 (ORCPT ); Wed, 12 Aug 2020 21:45:57 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9BFE92087C; Thu, 13 Aug 2020 01:45:56 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94) (envelope-from ) id 1k62JX-00750B-Lg; Wed, 12 Aug 2020 21:45:55 -0400 Message-ID: <20200813014555.550173612@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 12 Aug 2020 21:45:36 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Daniel Wagner , Tom Zanussi , "Srivatsa S. Bhat" Subject: [PATCH RT 2/6] workqueue: Sync with upstream References: <20200813014534.833107526@goodmis.org> MIME-Version: 1.0 Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org 5.4.54-rt33-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior This is an all-on-one patch reverting the following commits: workqueue: Don't assume that the callback has interrupts disabled sched/swait: Add swait_event_lock_irq() workqueue: Use swait for wq_manager_wait workqueue: Convert the locks to raw type and introducing the following commits from upstream: workqueue: Use rcuwait for wq_manager_wait workqueue: Convert the pool::lock and wq_mayday_lock to raw_spinlock_t as an replacement. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt (VMware) --- include/linux/swait.h | 14 -------------- kernel/workqueue.c | 28 +++++++++++++++++++--------- 2 files changed, 19 insertions(+), 23 deletions(-) diff --git a/include/linux/swait.h b/include/linux/swait.h index 21ae66cd41d3..f426a0661aa0 100644 --- a/include/linux/swait.h +++ b/include/linux/swait.h @@ -299,18 +299,4 @@ do { \ __ret; \ }) -#define __swait_event_lock_irq(wq, condition, lock, cmd) \ - ___swait_event(wq, condition, TASK_UNINTERRUPTIBLE, 0, \ - raw_spin_unlock_irq(&lock); \ - cmd; \ - schedule(); \ - raw_spin_lock_irq(&lock)) - -#define swait_event_lock_irq(wq_head, condition, lock) \ - do { \ - if (condition) \ - break; \ - __swait_event_lock_irq(wq_head, condition, lock, ); \ - } while (0) - #endif /* _LINUX_SWAIT_H */ diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 26341e8101ee..7c968aea01e1 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -50,7 +50,6 @@ #include #include #include -#include #include "workqueue_internal.h" @@ -302,7 +301,8 @@ static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ -static DECLARE_SWAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */ +/* wait for manager to go away */ +static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait); static LIST_HEAD(workqueues); /* PR: list of all workqueues */ static bool workqueue_freezing; /* PL: have wqs started freezing? */ @@ -1615,11 +1615,9 @@ EXPORT_SYMBOL_GPL(queue_work_node); void delayed_work_timer_fn(struct timer_list *t) { struct delayed_work *dwork = from_timer(dwork, t, timer); - unsigned long flags; - local_irq_save(flags); + /* should have been called from irqsafe timer with irq already off */ __queue_work(dwork->cpu, dwork->wq, &dwork->work); - local_irq_restore(flags); } EXPORT_SYMBOL(delayed_work_timer_fn); @@ -2147,7 +2145,7 @@ static bool manage_workers(struct worker *worker) pool->manager = NULL; pool->flags &= ~POOL_MANAGER_ACTIVE; - swake_up_one(&wq_manager_wait); + rcuwait_wake_up(&manager_wait); return true; } @@ -3511,6 +3509,18 @@ static void rcu_free_pool(struct rcu_head *rcu) kfree(pool); } +/* This returns with the lock held on success (pool manager is inactive). */ +static bool wq_manager_inactive(struct worker_pool *pool) +{ + raw_spin_lock_irq(&pool->lock); + + if (pool->flags & POOL_MANAGER_ACTIVE) { + raw_spin_unlock_irq(&pool->lock); + return false; + } + return true; +} + /** * put_unbound_pool - put a worker_pool * @pool: worker_pool to put @@ -3546,10 +3556,10 @@ static void put_unbound_pool(struct worker_pool *pool) * Become the manager and destroy all workers. This prevents * @pool's workers from blocking on attach_mutex. We're the last * manager and @pool gets freed with the flag set. + * Because of how wq_manager_inactive() works, we will hold the + * spinlock after a successful wait. */ - raw_spin_lock_irq(&pool->lock); - swait_event_lock_irq(wq_manager_wait, - !(pool->flags & POOL_MANAGER_ACTIVE), pool->lock); + rcuwait_wait_event(&manager_wait, wq_manager_inactive(pool)); pool->flags |= POOL_MANAGER_ACTIVE; while ((worker = first_idle_worker(pool)))