Merge branch 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue updates from Tejun Heo:
 "Mostly patches to initialize workqueue subsystem earlier and get rid
  of keventd_up().

  The patches were headed for the last merge cycle but got delayed due
  to a bug found late minute, which is fixed now.

  Also, to help debugging, destroy_workqueue() is more chatty now on a
  sanity check failure."

* 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: move wq_numa_init() to workqueue_init()
  workqueue: remove keventd_up()
  debugobj, workqueue: remove keventd_up() usage
  slab, workqueue: remove keventd_up() usage
  power, workqueue: remove keventd_up() usage
  tty, workqueue: remove keventd_up() usage
  mce, workqueue: remove keventd_up() usage
  workqueue: make workqueue available early during boot
  workqueue: dump workqueue state on sanity check failures in destroy_workqueue()

arch/x86/kernel/cpu/mcheck/mce.c

@@ -516,7 +516,7 @@ int mce_available(struct cpuinfo_x86 *c)
 
 static void mce_schedule_work(void)
 {
-	if (!mce_gen_pool_empty() && keventd_up())
+	if (!mce_gen_pool_empty())
 		schedule_work(&mce_work);
 }
 

drivers/tty/vt/vt.c

@@ -3923,10 +3923,6 @@ void unblank_screen(void)
  */
 static void blank_screen_t(unsigned long dummy)
 {
-	if (unlikely(!keventd_up())) {
-		mod_timer(&console_timer, jiffies + (blankinterval * HZ));
-		return;
-	}
 	blank_timer_expired = 1;
 	schedule_work(&console_work);
 }

include/linux/workqueue.h

@@ -603,14 +603,6 @@ static inline bool schedule_delayed_work(struct delayed_work *dwork,
 	return queue_delayed_work(system_wq, dwork, delay);
 }
 
-/**
- * keventd_up - is workqueue initialized yet?
- */
-static inline bool keventd_up(void)
-{
-	return system_wq != NULL;
-}
-
 #ifndef CONFIG_SMP
 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 {
@@ -645,4 +637,7 @@ int workqueue_online_cpu(unsigned int cpu);
 int workqueue_offline_cpu(unsigned int cpu);
 #endif
 
+int __init workqueue_init_early(void);
+int __init workqueue_init(void);
+
 #endif

init/main.c

@@ -553,6 +553,14 @@ asmlinkage __visible void __init start_kernel(void)
 		 "Interrupts were enabled *very* early, fixing it\n"))
 		local_irq_disable();
 	idr_init_cache();
+
+	/*
+	 * Allow workqueue creation and work item queueing/cancelling
+	 * early.  Work item execution depends on kthreads and starts after
+	 * workqueue_init().
+	 */
+	workqueue_init_early();
+
 	rcu_init();
 
 	/* trace_printk() and trace points may be used after this */
@@ -1009,6 +1017,8 @@ static noinline void __init kernel_init_freeable(void)
 
 	smp_prepare_cpus(setup_max_cpus);
 
+	workqueue_init();
+
 	do_pre_smp_initcalls();
 	lockup_detector_init();
 

kernel/power/qos.c

@@ -482,16 +482,7 @@ void pm_qos_update_request(struct pm_qos_request *req,
 		return;
 	}
 
-	/*
+	cancel_delayed_work_sync(&req->work);
-	 * This function may be called very early during boot, for example,
-	 * from of_clk_init(), where irq needs to stay disabled.
-	 * cancel_delayed_work_sync() assumes that irq is enabled on
-	 * invocation and re-enables it on return.  Avoid calling it until
-	 * workqueue is initialized.
-	 */
-	if (keventd_up())
-		cancel_delayed_work_sync(&req->work);
-
 	__pm_qos_update_request(req, new_value);
 }
 EXPORT_SYMBOL_GPL(pm_qos_update_request);

kernel/workqueue.c

@@ -290,6 +290,8 @@ module_param_named(disable_numa, wq_disable_numa, bool, 0444);
 static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT);
 module_param_named(power_efficient, wq_power_efficient, bool, 0444);
 
+static bool wq_online;			/* can kworkers be created yet? */
+
 static bool wq_numa_enabled;		/* unbound NUMA affinity enabled */
 
 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
@@ -2583,6 +2585,9 @@ void flush_workqueue(struct workqueue_struct *wq)
 	};
 	int next_color;
 
+	if (WARN_ON(!wq_online))
+		return;
+
 	lock_map_acquire(&wq->lockdep_map);
 	lock_map_release(&wq->lockdep_map);
 
@@ -2843,6 +2848,9 @@ bool flush_work(struct work_struct *work)
 {
 	struct wq_barrier barr;
 
+	if (WARN_ON(!wq_online))
+		return false;
+
 	lock_map_acquire(&work->lockdep_map);
 	lock_map_release(&work->lockdep_map);
 
@@ -2913,7 +2921,13 @@ static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
 	mark_work_canceling(work);
 	local_irq_restore(flags);
 
-	flush_work(work);
+	/*
+	 * This allows canceling during early boot.  We know that @work
+	 * isn't executing.
+	 */
+	if (wq_online)
+		flush_work(work);
+
 	clear_work_data(work);
 
 	/*
@@ -3364,7 +3378,7 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
 		goto fail;
 
 	/* create and start the initial worker */
-	if (!create_worker(pool))
+	if (wq_online && !create_worker(pool))
 		goto fail;
 
 	/* install */
@@ -3429,6 +3443,7 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
 {
 	struct workqueue_struct *wq = pwq->wq;
 	bool freezable = wq->flags & WQ_FREEZABLE;
+	unsigned long flags;
 
 	/* for @wq->saved_max_active */
 	lockdep_assert_held(&wq->mutex);
@@ -3437,7 +3452,8 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
 	if (!freezable && pwq->max_active == wq->saved_max_active)
 		return;
 
-	spin_lock_irq(&pwq->pool->lock);
+	/* this function can be called during early boot w/ irq disabled */
+	spin_lock_irqsave(&pwq->pool->lock, flags);
 
 	/*
 	 * During [un]freezing, the caller is responsible for ensuring that
@@ -3460,7 +3476,7 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
 		pwq->max_active = 0;
 	}
 
-	spin_unlock_irq(&pwq->pool->lock);
+	spin_unlock_irqrestore(&pwq->pool->lock, flags);
 }
 
 /* initialize newly alloced @pwq which is associated with @wq and @pool */
@@ -4033,6 +4049,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
 		for (i = 0; i < WORK_NR_COLORS; i++) {
 			if (WARN_ON(pwq->nr_in_flight[i])) {
 				mutex_unlock(&wq->mutex);
+				show_workqueue_state();
 				return;
 			}
 		}
@@ -4041,6 +4058,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
 		    WARN_ON(pwq->nr_active) ||
 		    WARN_ON(!list_empty(&pwq->delayed_works))) {
 			mutex_unlock(&wq->mutex);
+			show_workqueue_state();
 			return;
 		}
 	}
@@ -5467,7 +5485,17 @@ static void __init wq_numa_init(void)
 	wq_numa_enabled = true;
 }
 
-static int __init init_workqueues(void)
+/**
+ * workqueue_init_early - early init for workqueue subsystem
+ *
+ * This is the first half of two-staged workqueue subsystem initialization
+ * and invoked as soon as the bare basics - memory allocation, cpumasks and
+ * idr are up.  It sets up all the data structures and system workqueues
+ * and allows early boot code to create workqueues and queue/cancel work
+ * items.  Actual work item execution starts only after kthreads can be
+ * created and scheduled right before early initcalls.
+ */
+int __init workqueue_init_early(void)
 {
 	int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
 	int i, cpu;
@@ -5479,8 +5507,6 @@ static int __init init_workqueues(void)
 
 	pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
 
-	wq_numa_init();
-
 	/* initialize CPU pools */
 	for_each_possible_cpu(cpu) {
 		struct worker_pool *pool;
@@ -5500,16 +5526,6 @@ static int __init init_workqueues(void)
 		}
 	}
 
-	/* create the initial worker */
-	for_each_online_cpu(cpu) {
-		struct worker_pool *pool;
-
-		for_each_cpu_worker_pool(pool, cpu) {
-			pool->flags &= ~POOL_DISASSOCIATED;
-			BUG_ON(!create_worker(pool));
-		}
-	}
-
 	/* create default unbound and ordered wq attrs */
 	for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
 		struct workqueue_attrs *attrs;
@@ -5546,8 +5562,59 @@ static int __init init_workqueues(void)
 	       !system_power_efficient_wq ||
 	       !system_freezable_power_efficient_wq);
 
+	return 0;
+}
+
+/**
+ * workqueue_init - bring workqueue subsystem fully online
+ *
+ * This is the latter half of two-staged workqueue subsystem initialization
+ * and invoked as soon as kthreads can be created and scheduled.
+ * Workqueues have been created and work items queued on them, but there
+ * are no kworkers executing the work items yet.  Populate the worker pools
+ * with the initial workers and enable future kworker creations.
+ */
+int __init workqueue_init(void)
+{
+	struct workqueue_struct *wq;
+	struct worker_pool *pool;
+	int cpu, bkt;
+
+	/*
+	 * It'd be simpler to initialize NUMA in workqueue_init_early() but
+	 * CPU to node mapping may not be available that early on some
+	 * archs such as power and arm64.  As per-cpu pools created
+	 * previously could be missing node hint and unbound pools NUMA
+	 * affinity, fix them up.
+	 */
+	wq_numa_init();
+
+	mutex_lock(&wq_pool_mutex);
+
+	for_each_possible_cpu(cpu) {
+		for_each_cpu_worker_pool(pool, cpu) {
+			pool->node = cpu_to_node(cpu);
+		}
+	}
+
+	list_for_each_entry(wq, &workqueues, list)
+		wq_update_unbound_numa(wq, smp_processor_id(), true);
+
+	mutex_unlock(&wq_pool_mutex);
+
+	/* create the initial workers */
+	for_each_online_cpu(cpu) {
+		for_each_cpu_worker_pool(pool, cpu) {
+			pool->flags &= ~POOL_DISASSOCIATED;
+			BUG_ON(!create_worker(pool));
+		}
+	}
+
+	hash_for_each(unbound_pool_hash, bkt, pool, hash_node)
+		BUG_ON(!create_worker(pool));
+
+	wq_online = true;
 	wq_watchdog_init();
 
 	return 0;
 }
-early_initcall(init_workqueues);

lib/debugobjects.c

@@ -199,7 +199,7 @@ static void free_object(struct debug_obj *obj)
 	 * initialized:
 	 */
 	if (obj_pool_free > ODEBUG_POOL_SIZE && obj_cache)
-		sched = keventd_up();
+		sched = 1;
 	hlist_add_head(&obj->node, &obj_pool);
 	obj_pool_free++;
 	obj_pool_used--;

mm/slab.c

@@ -552,12 +552,7 @@ static void start_cpu_timer(int cpu)
 {
 	struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
 
-	/*
+	if (reap_work->work.func == NULL) {
-	 * When this gets called from do_initcalls via cpucache_init(),
-	 * init_workqueues() has already run, so keventd will be setup
-	 * at that time.
-	 */
-	if (keventd_up() && reap_work->work.func == NULL) {
 		init_reap_node(cpu);
 		INIT_DEFERRABLE_WORK(reap_work, cache_reap);
 		schedule_delayed_work_on(cpu, reap_work,