From 699ce097efe8f45bc5c055e4f12cb1e271c270d9 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 13 Mar 2013 16:51:35 -0700 Subject: [PATCH] workqueue: implement and use pwq_adjust_max_active() Rename pwq_set_max_active() to pwq_adjust_max_active() and move pool_workqueue->max_active synchronization and max_active determination logic into it. The new function should be called with workqueue_lock held for stable workqueue->saved_max_active, determines the current max_active value the target pool_workqueue should be using from @wq->saved_max_active and the state of the associated pool, and applies it with proper synchronization. The current two users - workqueue_set_max_active() and thaw_workqueues() - are updated accordingly. In addition, the manual freezing handling in __alloc_workqueue_key() and freeze_workqueues_begin() are replaced with calls to pwq_adjust_max_active(). This centralizes max_active handling so that it's less error-prone. Signed-off-by: Tejun Heo --- kernel/workqueue.c | 83 +++++++++++++++++++++++++----------------------------- 1 file changed, 38 insertions(+), 45 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index d519289..9e2ec4c 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3726,23 +3726,38 @@ static void pwq_unbound_release_workfn(struct work_struct *work) } /** - * pwq_set_max_active - adjust max_active of a pwq + * pwq_adjust_max_active - update a pwq's max_active to the current setting * @pwq: target pool_workqueue - * @max_active: new max_active value. - * - * Set @pwq->max_active to @max_active and activate delayed works if - * increased. * - * CONTEXT: - * spin_lock_irq(pool->lock). + * If @pwq isn't freezing, set @pwq->max_active to the associated + * workqueue's saved_max_active and activate delayed work items + * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. */ -static void pwq_set_max_active(struct pool_workqueue *pwq, int max_active) +static void pwq_adjust_max_active(struct pool_workqueue *pwq) { - pwq->max_active = max_active; + struct workqueue_struct *wq = pwq->wq; + bool freezable = wq->flags & WQ_FREEZABLE; + + /* for @wq->saved_max_active */ + lockdep_assert_held(&workqueue_lock); + + /* fast exit for non-freezable wqs */ + if (!freezable && pwq->max_active == wq->saved_max_active) + return; + + spin_lock(&pwq->pool->lock); + + if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) { + pwq->max_active = wq->saved_max_active; - while (!list_empty(&pwq->delayed_works) && - pwq->nr_active < pwq->max_active) - pwq_activate_first_delayed(pwq); + while (!list_empty(&pwq->delayed_works) && + pwq->nr_active < pwq->max_active) + pwq_activate_first_delayed(pwq); + } else { + pwq->max_active = 0; + } + + spin_unlock(&pwq->pool->lock); } static void init_and_link_pwq(struct pool_workqueue *pwq, @@ -3932,15 +3947,14 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, goto err_destroy; /* - * workqueue_lock protects global freeze state and workqueues - * list. Grab it, set max_active accordingly and add the new - * workqueue to workqueues list. + * workqueue_lock protects global freeze state and workqueues list. + * Grab it, adjust max_active and add the new workqueue to + * workqueues list. */ spin_lock_irq(&workqueue_lock); - if (workqueue_freezing && wq->flags & WQ_FREEZABLE) - for_each_pwq(pwq, wq) - pwq->max_active = 0; + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); list_add(&wq->list, &workqueues); @@ -4055,17 +4069,8 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) wq->saved_max_active = max_active; - for_each_pwq(pwq, wq) { - struct worker_pool *pool = pwq->pool; - - spin_lock(&pool->lock); - - if (!(wq->flags & WQ_FREEZABLE) || - !(pool->flags & POOL_FREEZING)) - pwq_set_max_active(pwq, max_active); - - spin_unlock(&pool->lock); - } + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); spin_unlock_irq(&workqueue_lock); } @@ -4358,14 +4363,8 @@ void freeze_workqueues_begin(void) /* suppress further executions by setting max_active to zero */ list_for_each_entry(wq, &workqueues, list) { - if (!(wq->flags & WQ_FREEZABLE)) - continue; - - for_each_pwq(pwq, wq) { - spin_lock(&pwq->pool->lock); - pwq->max_active = 0; - spin_unlock(&pwq->pool->lock); - } + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); } spin_unlock_irq(&workqueue_lock); @@ -4445,14 +4444,8 @@ void thaw_workqueues(void) /* restore max_active and repopulate worklist */ list_for_each_entry(wq, &workqueues, list) { - if (!(wq->flags & WQ_FREEZABLE)) - continue; - - for_each_pwq(pwq, wq) { - spin_lock(&pwq->pool->lock); - pwq_set_max_active(pwq, wq->saved_max_active); - spin_unlock(&pwq->pool->lock); - } + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); } /* kick workers */ -- 2.7.4