diff options
| -rw-r--r-- | kernel/workqueue.c | 90 |
1 files changed, 65 insertions, 25 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index bc2e09a8ea61..914b845ad4ff 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -248,7 +248,7 @@ struct workqueue_struct { struct list_head flusher_overflow; /* WQ: flush overflow list */ struct list_head maydays; /* MD: pwqs requesting rescue */ - struct worker *rescuer; /* I: rescue worker */ + struct worker *rescuer; /* MD: rescue worker */ int nr_drainers; /* WQ: drain in progress */ int saved_max_active; /* WQ: saved pwq max_active */ @@ -355,6 +355,7 @@ EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); static int worker_thread(void *__worker); static void workqueue_sysfs_unregister(struct workqueue_struct *wq); +static void show_pwq(struct pool_workqueue *pwq); #define CREATE_TRACE_POINTS #include <trace/events/workqueue.h> @@ -425,7 +426,8 @@ static void workqueue_sysfs_unregister(struct workqueue_struct *wq); * ignored. */ #define for_each_pwq(pwq, wq) \ - list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ + list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ + lockdep_is_held(&wq->mutex)) \ if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ else @@ -2532,8 +2534,14 @@ repeat: */ if (need_to_create_worker(pool)) { spin_lock(&wq_mayday_lock); - get_pwq(pwq); - list_move_tail(&pwq->mayday_node, &wq->maydays); + /* + * Queue iff we aren't racing destruction + * and somebody else hasn't queued it already. + */ + if (wq->rescuer && list_empty(&pwq->mayday_node)) { + get_pwq(pwq); + list_add_tail(&pwq->mayday_node, &wq->maydays); + } spin_unlock(&wq_mayday_lock); } } @@ -4314,6 +4322,22 @@ err_destroy: } EXPORT_SYMBOL_GPL(alloc_workqueue); +static bool pwq_busy(struct pool_workqueue *pwq) +{ + int i; + + for (i = 0; i < WORK_NR_COLORS; i++) + if (pwq->nr_in_flight[i]) + return true; + + if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) + return true; + if (pwq->nr_active || !list_empty(&pwq->delayed_works)) + return true; + + return false; +} + /** * destroy_workqueue - safely terminate a workqueue * @wq: target workqueue @@ -4325,31 +4349,51 @@ void destroy_workqueue(struct workqueue_struct *wq) struct pool_workqueue *pwq; int node; + /* + * Remove it from sysfs first so that sanity check failure doesn't + * lead to sysfs name conflicts. + */ + workqueue_sysfs_unregister(wq); + /* drain it before proceeding with destruction */ drain_workqueue(wq); - /* sanity checks */ - mutex_lock(&wq->mutex); - for_each_pwq(pwq, wq) { - int i; + /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ + if (wq->rescuer) { + struct worker *rescuer = wq->rescuer; - for (i = 0; i < WORK_NR_COLORS; i++) { - if (WARN_ON(pwq->nr_in_flight[i])) { - mutex_unlock(&wq->mutex); - show_workqueue_state(); - return; - } - } + /* this prevents new queueing */ + spin_lock_irq(&wq_mayday_lock); + wq->rescuer = NULL; + spin_unlock_irq(&wq_mayday_lock); + + /* rescuer will empty maydays list before exiting */ + kthread_stop(rescuer->task); + kfree(rescuer); + } - if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) || - WARN_ON(pwq->nr_active) || - WARN_ON(!list_empty(&pwq->delayed_works))) { + /* + * Sanity checks - grab all the locks so that we wait for all + * in-flight operations which may do put_pwq(). + */ + mutex_lock(&wq_pool_mutex); + mutex_lock(&wq->mutex); + for_each_pwq(pwq, wq) { + spin_lock_irq(&pwq->pool->lock); + if (WARN_ON(pwq_busy(pwq))) { + pr_warning("%s: %s has the following busy pwq\n", + __func__, wq->name); + show_pwq(pwq); + spin_unlock_irq(&pwq->pool->lock); mutex_unlock(&wq->mutex); + mutex_unlock(&wq_pool_mutex); show_workqueue_state(); return; } + spin_unlock_irq(&pwq->pool->lock); } mutex_unlock(&wq->mutex); + mutex_unlock(&wq_pool_mutex); /* * wq list is used to freeze wq, remove from list after @@ -4359,11 +4403,6 @@ void destroy_workqueue(struct workqueue_struct *wq) list_del_rcu(&wq->list); mutex_unlock(&wq_pool_mutex); - workqueue_sysfs_unregister(wq); - - if (wq->rescuer) - kthread_stop(wq->rescuer->task); - if (!(wq->flags & WQ_UNBOUND)) { wq_unregister_lockdep(wq); /* @@ -4638,7 +4677,8 @@ static void show_pwq(struct pool_workqueue *pwq) pr_info(" pwq %d:", pool->id); pr_cont_pool_info(pool); - pr_cont(" active=%d/%d%s\n", pwq->nr_active, pwq->max_active, + pr_cont(" active=%d/%d refcnt=%d%s\n", + pwq->nr_active, pwq->max_active, pwq->refcnt, !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); hash_for_each(pool->busy_hash, bkt, worker, hentry) { @@ -4657,7 +4697,7 @@ static void show_pwq(struct pool_workqueue *pwq) pr_cont("%s %d%s:%ps", comma ? "," : "", task_pid_nr(worker->task), - worker == pwq->wq->rescuer ? "(RESCUER)" : "", + worker->rescue_wq ? "(RESCUER)" : "", worker->current_func); list_for_each_entry(work, &worker->scheduled, entry) pr_cont_work(false, work); |