workqueue: separate out and refactor the locking of applying attrs
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. tj: minor updates to comments Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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@ -3621,6 +3621,46 @@ static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
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mutex_unlock(&ctx->wq->mutex);
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}
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static void apply_wqattrs_lock(void)
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{
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/* CPUs should stay stable across pwq creations and installations */
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get_online_cpus();
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mutex_lock(&wq_pool_mutex);
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}
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static void apply_wqattrs_unlock(void)
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{
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mutex_unlock(&wq_pool_mutex);
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put_online_cpus();
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}
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static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
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const struct workqueue_attrs *attrs)
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{
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struct apply_wqattrs_ctx *ctx;
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int ret = -ENOMEM;
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/* only unbound workqueues can change attributes */
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if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
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return -EINVAL;
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/* creating multiple pwqs breaks ordering guarantee */
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if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
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return -EINVAL;
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ctx = apply_wqattrs_prepare(wq, attrs);
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/* the ctx has been prepared successfully, let's commit it */
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if (ctx) {
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apply_wqattrs_commit(ctx);
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ret = 0;
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}
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apply_wqattrs_cleanup(ctx);
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return ret;
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}
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/**
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* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
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* @wq: the target workqueue
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@ -3640,37 +3680,11 @@ static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
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int apply_workqueue_attrs(struct workqueue_struct *wq,
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const struct workqueue_attrs *attrs)
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{
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struct apply_wqattrs_ctx *ctx;
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int ret = -ENOMEM;
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int ret;
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/* only unbound workqueues can change attributes */
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if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
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return -EINVAL;
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/* creating multiple pwqs breaks ordering guarantee */
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if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
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return -EINVAL;
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/*
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* CPUs should stay stable across pwq creations and installations.
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* Pin CPUs, determine the target cpumask for each node and create
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* pwqs accordingly.
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*/
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get_online_cpus();
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mutex_lock(&wq_pool_mutex);
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ctx = apply_wqattrs_prepare(wq, attrs);
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/* the ctx has been prepared successfully, let's commit it */
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if (ctx) {
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apply_wqattrs_commit(ctx);
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ret = 0;
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}
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mutex_unlock(&wq_pool_mutex);
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put_online_cpus();
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apply_wqattrs_cleanup(ctx);
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apply_wqattrs_lock();
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ret = apply_workqueue_attrs_locked(wq, attrs);
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apply_wqattrs_unlock();
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return ret;
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}
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@ -4799,10 +4813,9 @@ int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
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if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL))
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return -ENOMEM;
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get_online_cpus();
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cpumask_and(cpumask, cpumask, cpu_possible_mask);
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if (!cpumask_empty(cpumask)) {
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mutex_lock(&wq_pool_mutex);
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apply_wqattrs_lock();
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/* save the old wq_unbound_cpumask. */
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cpumask_copy(saved_cpumask, wq_unbound_cpumask);
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@ -4815,9 +4828,8 @@ int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
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if (ret < 0)
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cpumask_copy(wq_unbound_cpumask, saved_cpumask);
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mutex_unlock(&wq_pool_mutex);
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apply_wqattrs_unlock();
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}
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put_online_cpus();
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free_cpumask_var(saved_cpumask);
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return ret;
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