From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754572AbaEVK5P (ORCPT ); Thu, 22 May 2014 06:57:15 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:3087 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752731AbaEVK5N (ORCPT ); Thu, 22 May 2014 06:57:13 -0400 X-IronPort-AV: E=Sophos;i="4.98,886,1392134400"; d="scan'208";a="30870289" From: Lai Jiangshan To: CC: Tejun Heo , Lai Jiangshan Subject: [PATCH] workqueue: remove the confusing POOL_FREEZING Date: Thu, 22 May 2014 19:01:16 +0800 Message-ID: <1400756486-12089-1-git-send-email-laijs@cn.fujitsu.com> X-Mailer: git-send-email 1.7.4.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.167.226.103] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While freezing takes place globally, its execution is per-workqueue; however, the current implementation makes use of the per-worker_pool POOL_FREEZING flag. While it's not broken, the flag makes the code more confusing and complicates freeze_workqueues_begin() and thaw_workqueues() by requiring them to walk through all pools. So we remove the POOL_FREEZING and use workqueue_freezing instead. Signed-off-by: Lai Jiangshan --- kernel/workqueue.c | 32 +++++++------------------------- 1 files changed, 7 insertions(+), 25 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 98b38b5..a87de61 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -69,7 +69,6 @@ enum { * worker_attach_to_pool() is in progress. */ POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ - POOL_FREEZING = 1 << 3, /* freeze in progress */ /* worker flags */ WORKER_DIE = 1 << 1, /* die die die */ @@ -3532,9 +3531,6 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) if (!pool || init_worker_pool(pool) < 0) goto fail; - if (workqueue_freezing) - pool->flags |= POOL_FREEZING; - lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ copy_workqueue_attrs(pool->attrs, attrs); @@ -3641,7 +3637,12 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq) spin_lock_irq(&pwq->pool->lock); - if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) { + /* + * pwq_adjust_max_active() is invoked at least once + * after workqueue_freezing is changed, so it can fetch + * the workqueue_freezing without wq_pool_mutex held. + */ + if (!freezable || !workqueue_freezing) { pwq->max_active = wq->saved_max_active; while (!list_empty(&pwq->delayed_works) && @@ -4750,24 +4751,14 @@ EXPORT_SYMBOL_GPL(work_on_cpu); */ void freeze_workqueues_begin(void) { - struct worker_pool *pool; struct workqueue_struct *wq; struct pool_workqueue *pwq; - int pi; mutex_lock(&wq_pool_mutex); WARN_ON_ONCE(workqueue_freezing); workqueue_freezing = true; - /* set FREEZING */ - for_each_pool(pool, pi) { - spin_lock_irq(&pool->lock); - WARN_ON_ONCE(pool->flags & POOL_FREEZING); - pool->flags |= POOL_FREEZING; - spin_unlock_irq(&pool->lock); - } - list_for_each_entry(wq, &workqueues, list) { mutex_lock(&wq->mutex); for_each_pwq(pwq, wq) @@ -4837,21 +4828,13 @@ void thaw_workqueues(void) { struct workqueue_struct *wq; struct pool_workqueue *pwq; - struct worker_pool *pool; - int pi; mutex_lock(&wq_pool_mutex); if (!workqueue_freezing) goto out_unlock; - /* clear FREEZING */ - for_each_pool(pool, pi) { - spin_lock_irq(&pool->lock); - WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); - pool->flags &= ~POOL_FREEZING; - spin_unlock_irq(&pool->lock); - } + workqueue_freezing = false; /* restore max_active and repopulate worklist */ list_for_each_entry(wq, &workqueues, list) { @@ -4861,7 +4844,6 @@ void thaw_workqueues(void) mutex_unlock(&wq->mutex); } - workqueue_freezing = false; out_unlock: mutex_unlock(&wq_pool_mutex); } -- 1.7.4.4