Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754418AbbESKAa (ORCPT ); Tue, 19 May 2015 06:00:30 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:15665 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753153AbbESKAN (ORCPT ); Tue, 19 May 2015 06:00:13 -0400 X-IronPort-AV: E=Sophos;i="5.01,1,1399996800"; d="scan'208";a="92458505" From: Lai Jiangshan To: CC: Lai Jiangshan , Tejun Heo Subject: [PATCH 1/2] workqueue: separate out and refactor the locking of applying attrs Date: Tue, 19 May 2015 18:03:47 +0800 Message-ID: <1432029828-3386-2-git-send-email-laijs@cn.fujitsu.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1432029828-3386-1-git-send-email-laijs@cn.fujitsu.com> References: <1432029828-3386-1-git-send-email-laijs@cn.fujitsu.com> 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 Content-Length: 4971 Lines: 152 Applying attrs requires two locks: get_online_cpus() and wq_pool_mutex, and this code is duplicated at two places (apply_workqueue_attrs() and workqueue_set_unbound_cpumask()). So we separate out this locking code into apply_wqattrs_[un]lock() and do a minor refactor on apply_workqueue_attrs(). The apply_wqattrs_[un]lock() will be also used on later patch for ensuring attrs changes are properly synchronized. Signed-off-by: Lai Jiangshan --- kernel/workqueue.c | 82 ++++++++++++++++++++++++++++++++---------------------- 1 file changed, 49 insertions(+), 33 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 4a9f65b..1c950f9 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3621,24 +3621,25 @@ static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) mutex_unlock(&ctx->wq->mutex); } -/** - * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue - * @wq: the target workqueue - * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() - * - * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA - * machines, this function maps a separate pwq to each NUMA node with - * possibles CPUs in @attrs->cpumask so that work items are affine to the - * NUMA node it was issued on. Older pwqs are released as in-flight work - * items finish. Note that a work item which repeatedly requeues itself - * back-to-back will stay on its current pwq. - * - * Performs GFP_KERNEL allocations. - * - * Return: 0 on success and -errno on failure. - */ -int apply_workqueue_attrs(struct workqueue_struct *wq, - const struct workqueue_attrs *attrs) +static void apply_wqattrs_lock(void) +{ + /* + * CPUs should stay stable across pwq creations and installations. + * Pin CPUs, determine the target cpumask for each node and create + * pwqs accordingly. + */ + get_online_cpus(); + mutex_lock(&wq_pool_mutex); +} + +static void apply_wqattrs_unlock(void) +{ + mutex_unlock(&wq_pool_mutex); + put_online_cpus(); +} + +static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, + const struct workqueue_attrs *attrs) { struct apply_wqattrs_ctx *ctx; int ret = -ENOMEM; @@ -3651,14 +3652,6 @@ int apply_workqueue_attrs(struct workqueue_struct *wq, if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))) return -EINVAL; - /* - * CPUs should stay stable across pwq creations and installations. - * Pin CPUs, determine the target cpumask for each node and create - * pwqs accordingly. - */ - get_online_cpus(); - mutex_lock(&wq_pool_mutex); - ctx = apply_wqattrs_prepare(wq, attrs); /* the ctx has been prepared successfully, let's commit it */ @@ -3667,15 +3660,40 @@ int apply_workqueue_attrs(struct workqueue_struct *wq, ret = 0; } - mutex_unlock(&wq_pool_mutex); - put_online_cpus(); - apply_wqattrs_cleanup(ctx); return ret; } /** + * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue + * @wq: the target workqueue + * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() + * + * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA + * machines, this function maps a separate pwq to each NUMA node with + * possibles CPUs in @attrs->cpumask so that work items are affine to the + * NUMA node it was issued on. Older pwqs are released as in-flight work + * items finish. Note that a work item which repeatedly requeues itself + * back-to-back will stay on its current pwq. + * + * Performs GFP_KERNEL allocations. + * + * Return: 0 on success and -errno on failure. + */ +int apply_workqueue_attrs(struct workqueue_struct *wq, + const struct workqueue_attrs *attrs) +{ + int ret; + + apply_wqattrs_lock(); + ret = apply_workqueue_attrs_locked(wq, attrs); + apply_wqattrs_unlock(); + + return ret; +} + +/** * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug * @wq: the target workqueue * @cpu: the CPU coming up or going down @@ -4799,10 +4817,9 @@ int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL)) return -ENOMEM; - get_online_cpus(); cpumask_and(cpumask, cpumask, cpu_possible_mask); if (!cpumask_empty(cpumask)) { - mutex_lock(&wq_pool_mutex); + apply_wqattrs_lock(); /* save the old wq_unbound_cpumask. */ cpumask_copy(saved_cpumask, wq_unbound_cpumask); @@ -4815,9 +4832,8 @@ int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) if (ret < 0) cpumask_copy(wq_unbound_cpumask, saved_cpumask); - mutex_unlock(&wq_pool_mutex); + apply_wqattrs_unlock(); } - put_online_cpus(); free_cpumask_var(saved_cpumask); return ret; -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/