Merge branch 'for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue updates from Tejun Heo:
 "There is a long-standing subtle destroy_workqueue() bug where a
  workqueue can be destroyed while internal work items used for flushing
  are still in flight. Lai fixed it by assigning a flush color to the
  internal work items so that they are correctly waited for during
  destruction.

  Other than that, all are minor cleanups"

* 'for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Remove unused WORK_NO_COLOR
  workqueue: Assign a color to barrier work items
  workqueue: Mark barrier work with WORK_STRUCT_INACTIVE
  workqueue: Change the code of calculating work_flags in insert_wq_barrier()
  workqueue: Change arguement of pwq_dec_nr_in_flight()
  workqueue: Rename "delayed" (delayed by active management) to "inactive"
  workqueue: Replace deprecated CPU-hotplug functions.
  workqueue: Replace deprecated ida_simple_*() with ida_alloc()/ida_free()
  workqueue: Fix typo in comments
  workqueue: Fix possible memory leaks in wq_numa_init()

2 files changed, 111 insertions, 78 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f148eacda55a..33a6b4a2443d 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -205,9 +205,26 @@ struct pool_workqueue {
 	int			refcnt;		/* L: reference count */
 	int			nr_in_flight[WORK_NR_COLORS];
 						/* L: nr of in_flight works */
+
+	/*
+	 * nr_active management and WORK_STRUCT_INACTIVE:
+	 *
+	 * When pwq->nr_active >= max_active, new work item is queued to
+	 * pwq->inactive_works instead of pool->worklist and marked with
+	 * WORK_STRUCT_INACTIVE.
+	 *
+	 * All work items marked with WORK_STRUCT_INACTIVE do not participate
+	 * in pwq->nr_active and all work items in pwq->inactive_works are
+	 * marked with WORK_STRUCT_INACTIVE.  But not all WORK_STRUCT_INACTIVE
+	 * work items are in pwq->inactive_works.  Some of them are ready to
+	 * run in pool->worklist or worker->scheduled.  Those work itmes are
+	 * only struct wq_barrier which is used for flush_work() and should
+	 * not participate in pwq->nr_active.  For non-barrier work item, it
+	 * is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works.
+	 */
 	int			nr_active;	/* L: nr of active works */
 	int			max_active;	/* L: max active works */
-	struct list_head	delayed_works;	/* L: delayed works */
+	struct list_head	inactive_works;	/* L: inactive works */
 	struct list_head	pwqs_node;	/* WR: node on wq->pwqs */
 	struct list_head	mayday_node;	/* MD: node on wq->maydays */
 
@@ -524,7 +541,7 @@ static inline void debug_work_deactivate(struct work_struct *work) { }
 #endif
 
 /**
- * worker_pool_assign_id - allocate ID and assing it to @pool
+ * worker_pool_assign_id - allocate ID and assign it to @pool
  * @pool: the pool pointer of interest
  *
  * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
@@ -579,9 +596,9 @@ static unsigned int work_color_to_flags(int color)
 	return color << WORK_STRUCT_COLOR_SHIFT;
 }
 
-static int get_work_color(struct work_struct *work)
+static int get_work_color(unsigned long work_data)
 {
-	return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
+	return (work_data >> WORK_STRUCT_COLOR_SHIFT) &
 		((1 << WORK_STRUCT_COLOR_BITS) - 1);
 }
 
@@ -1136,7 +1153,7 @@ static void put_pwq_unlocked(struct pool_workqueue *pwq)
 	}
 }
 
-static void pwq_activate_delayed_work(struct work_struct *work)
+static void pwq_activate_inactive_work(struct work_struct *work)
 {
 	struct pool_workqueue *pwq = get_work_pwq(work);
 
@@ -1144,22 +1161,22 @@ static void pwq_activate_delayed_work(struct work_struct *work)
 	if (list_empty(&pwq->pool->worklist))
 		pwq->pool->watchdog_ts = jiffies;
 	move_linked_works(work, &pwq->pool->worklist, NULL);
-	__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
+	__clear_bit(WORK_STRUCT_INACTIVE_BIT, work_data_bits(work));
 	pwq->nr_active++;
 }
 
-static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
+static void pwq_activate_first_inactive(struct pool_workqueue *pwq)
 {
-	struct work_struct *work = list_first_entry(&pwq->delayed_works,
+	struct work_struct *work = list_first_entry(&pwq->inactive_works,
 						    struct work_struct, entry);
 
-	pwq_activate_delayed_work(work);
+	pwq_activate_inactive_work(work);
 }
 
 /**
  * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
  * @pwq: pwq of interest
- * @color: color of work which left the queue
+ * @work_data: work_data of work which left the queue
  *
  * A work either has completed or is removed from pending queue,
  * decrement nr_in_flight of its pwq and handle workqueue flushing.
@@ -1167,21 +1184,21 @@ static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
  * CONTEXT:
  * raw_spin_lock_irq(pool->lock).
  */
-static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
+static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data)
 {
-	/* uncolored work items don't participate in flushing or nr_active */
-	if (color == WORK_NO_COLOR)
-		goto out_put;
-
-	pwq->nr_in_flight[color]--;
+	int color = get_work_color(work_data);
 
-	pwq->nr_active--;
-	if (!list_empty(&pwq->delayed_works)) {
-		/* one down, submit a delayed one */
-		if (pwq->nr_active < pwq->max_active)
-			pwq_activate_first_delayed(pwq);
+	if (!(work_data & WORK_STRUCT_INACTIVE)) {
+		pwq->nr_active--;
+		if (!list_empty(&pwq->inactive_works)) {
+			/* one down, submit an inactive one */
+			if (pwq->nr_active < pwq->max_active)
+				pwq_activate_first_inactive(pwq);
+		}
 	}
 
+	pwq->nr_in_flight[color]--;
+
 	/* is flush in progress and are we at the flushing tip? */
 	if (likely(pwq->flush_color != color))
 		goto out_put;
@@ -1281,17 +1298,21 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
 		debug_work_deactivate(work);
 
 		/*
-		 * A delayed work item cannot be grabbed directly because
-		 * it might have linked NO_COLOR work items which, if left
-		 * on the delayed_list, will confuse pwq->nr_active
+		 * A cancelable inactive work item must be in the
+		 * pwq->inactive_works since a queued barrier can't be
+		 * canceled (see the comments in insert_wq_barrier()).
+		 *
+		 * An inactive work item cannot be grabbed directly because
+		 * it might have linked barrier work items which, if left
+		 * on the inactive_works list, will confuse pwq->nr_active
 		 * management later on and cause stall.  Make sure the work
 		 * item is activated before grabbing.
 		 */
-		if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
-			pwq_activate_delayed_work(work);
+		if (*work_data_bits(work) & WORK_STRUCT_INACTIVE)
+			pwq_activate_inactive_work(work);
 
 		list_del_init(&work->entry);
-		pwq_dec_nr_in_flight(pwq, get_work_color(work));
+		pwq_dec_nr_in_flight(pwq, *work_data_bits(work));
 
 		/* work->data points to pwq iff queued, point to pool */
 		set_work_pool_and_keep_pending(work, pool->id);
@@ -1490,8 +1511,8 @@ retry:
 		if (list_empty(worklist))
 			pwq->pool->watchdog_ts = jiffies;
 	} else {
-		work_flags |= WORK_STRUCT_DELAYED;
-		worklist = &pwq->delayed_works;
+		work_flags |= WORK_STRUCT_INACTIVE;
+		worklist = &pwq->inactive_works;
 	}
 
 	debug_work_activate(work);
@@ -1912,14 +1933,14 @@ static void worker_detach_from_pool(struct worker *worker)
  */
 static struct worker *create_worker(struct worker_pool *pool)
 {
-	struct worker *worker = NULL;
-	int id = -1;
+	struct worker *worker;
+	int id;
 	char id_buf[16];
 
 	/* ID is needed to determine kthread name */
-	id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
+	id = ida_alloc(&pool->worker_ida, GFP_KERNEL);
 	if (id < 0)
-		goto fail;
+		return NULL;
 
 	worker = alloc_worker(pool->node);
 	if (!worker)
@@ -1954,8 +1975,7 @@ static struct worker *create_worker(struct worker_pool *pool)
 	return worker;
 
 fail:
-	if (id >= 0)
-		ida_simple_remove(&pool->worker_ida, id);
+	ida_free(&pool->worker_ida, id);
 	kfree(worker);
 	return NULL;
 }
@@ -2173,7 +2193,7 @@ __acquires(&pool->lock)
 	struct pool_workqueue *pwq = get_work_pwq(work);
 	struct worker_pool *pool = worker->pool;
 	bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
-	int work_color;
+	unsigned long work_data;
 	struct worker *collision;
 #ifdef CONFIG_LOCKDEP
 	/*
@@ -2209,7 +2229,8 @@ __acquires(&pool->lock)
 	worker->current_work = work;
 	worker->current_func = work->func;
 	worker->current_pwq = pwq;
-	work_color = get_work_color(work);
+	work_data = *work_data_bits(work);
+	worker->current_color = get_work_color(work_data);
 
 	/*
 	 * Record wq name for cmdline and debug reporting, may get
@@ -2315,7 +2336,8 @@ __acquires(&pool->lock)
 	worker->current_work = NULL;
 	worker->current_func = NULL;
 	worker->current_pwq = NULL;
-	pwq_dec_nr_in_flight(pwq, work_color);
+	worker->current_color = INT_MAX;
+	pwq_dec_nr_in_flight(pwq, work_data);
 }
 
 /**
@@ -2378,7 +2400,7 @@ woke_up:
 		set_pf_worker(false);
 
 		set_task_comm(worker->task, "kworker/dying");
-		ida_simple_remove(&pool->worker_ida, worker->id);
+		ida_free(&pool->worker_ida, worker->id);
 		worker_detach_from_pool(worker);
 		kfree(worker);
 		return 0;
@@ -2531,7 +2553,7 @@ repeat:
 			/*
 			 * The above execution of rescued work items could
 			 * have created more to rescue through
-			 * pwq_activate_first_delayed() or chained
+			 * pwq_activate_first_inactive() or chained
 			 * queueing.  Let's put @pwq back on mayday list so
 			 * that such back-to-back work items, which may be
 			 * being used to relieve memory pressure, don't
@@ -2658,8 +2680,9 @@ static void insert_wq_barrier(struct pool_workqueue *pwq,
 			      struct wq_barrier *barr,
 			      struct work_struct *target, struct worker *worker)
 {
+	unsigned int work_flags = 0;
+	unsigned int work_color;
 	struct list_head *head;
-	unsigned int linked = 0;
 
 	/*
 	 * debugobject calls are safe here even with pool->lock locked
@@ -2674,24 +2697,31 @@ static void insert_wq_barrier(struct pool_workqueue *pwq,
 
 	barr->task = current;
 
+	/* The barrier work item does not participate in pwq->nr_active. */
+	work_flags |= WORK_STRUCT_INACTIVE;
+
 	/*
 	 * If @target is currently being executed, schedule the
 	 * barrier to the worker; otherwise, put it after @target.
 	 */
-	if (worker)
+	if (worker) {
 		head = worker->scheduled.next;
-	else {
+		work_color = worker->current_color;
+	} else {
 		unsigned long *bits = work_data_bits(target);
 
 		head = target->entry.next;
 		/* there can already be other linked works, inherit and set */
-		linked = *bits & WORK_STRUCT_LINKED;
+		work_flags |= *bits & WORK_STRUCT_LINKED;
+		work_color = get_work_color(*bits);
 		__set_bit(WORK_STRUCT_LINKED_BIT, bits);
 	}
 
+	pwq->nr_in_flight[work_color]++;
+	work_flags |= work_color_to_flags(work_color);
+
 	debug_work_activate(&barr->work);
-	insert_work(pwq, &barr->work, head,
-		    work_color_to_flags(WORK_NO_COLOR) | linked);
+	insert_work(pwq, &barr->work, head, work_flags);
 }
 
 /**
@@ -2957,7 +2987,7 @@ reflush:
 		bool drained;
 
 		raw_spin_lock_irq(&pwq->pool->lock);
-		drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
+		drained = !pwq->nr_active && list_empty(&pwq->inactive_works);
 		raw_spin_unlock_irq(&pwq->pool->lock);
 
 		if (drained)
@@ -3293,7 +3323,7 @@ int schedule_on_each_cpu(work_func_t func)
 	if (!works)
 		return -ENOMEM;
 
-	get_online_cpus();
+	cpus_read_lock();
 
 	for_each_online_cpu(cpu) {
 		struct work_struct *work = per_cpu_ptr(works, cpu);
@@ -3305,7 +3335,7 @@ int schedule_on_each_cpu(work_func_t func)
 	for_each_online_cpu(cpu)
 		flush_work(per_cpu_ptr(works, cpu));
 
-	put_online_cpus();
+	cpus_read_unlock();
 	free_percpu(works);
 	return 0;
 }
@@ -3713,7 +3743,7 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
  * @pwq: target pool_workqueue
  *
  * If @pwq isn't freezing, set @pwq->max_active to the associated
- * workqueue's saved_max_active and activate delayed work items
+ * workqueue's saved_max_active and activate inactive work items
  * accordingly.  If @pwq is freezing, clear @pwq->max_active to zero.
  */
 static void pwq_adjust_max_active(struct pool_workqueue *pwq)
@@ -3742,9 +3772,9 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
 
 		pwq->max_active = wq->saved_max_active;
 
-		while (!list_empty(&pwq->delayed_works) &&
+		while (!list_empty(&pwq->inactive_works) &&
 		       pwq->nr_active < pwq->max_active) {
-			pwq_activate_first_delayed(pwq);
+			pwq_activate_first_inactive(pwq);
 			kick = true;
 		}
 
@@ -3763,7 +3793,7 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
 	raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
 }
 
-/* initialize newly alloced @pwq which is associated with @wq and @pool */
+/* initialize newly allocated @pwq which is associated with @wq and @pool */
 static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
 		     struct worker_pool *pool)
 {
@@ -3775,7 +3805,7 @@ static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
 	pwq->wq = wq;
 	pwq->flush_color = -1;
 	pwq->refcnt = 1;
-	INIT_LIST_HEAD(&pwq->delayed_works);
+	INIT_LIST_HEAD(&pwq->inactive_works);
 	INIT_LIST_HEAD(&pwq->pwqs_node);
 	INIT_LIST_HEAD(&pwq->mayday_node);
 	INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
@@ -4016,14 +4046,14 @@ static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
 static void apply_wqattrs_lock(void)
 {
 	/* CPUs should stay stable across pwq creations and installations */
-	get_online_cpus();
+	cpus_read_lock();
 	mutex_lock(&wq_pool_mutex);
 }
 
 static void apply_wqattrs_unlock(void)
 {
 	mutex_unlock(&wq_pool_mutex);
-	put_online_cpus();
+	cpus_read_unlock();
 }
 
 static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
@@ -4068,7 +4098,7 @@ static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
  *
  * Performs GFP_KERNEL allocations.
  *
- * Assumes caller has CPU hotplug read exclusion, i.e. get_online_cpus().
+ * Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock().
  *
  * Return: 0 on success and -errno on failure.
  */
@@ -4196,7 +4226,7 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
 		return 0;
 	}
 
-	get_online_cpus();
+	cpus_read_lock();
 	if (wq->flags & __WQ_ORDERED) {
 		ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
 		/* there should only be single pwq for ordering guarantee */
@@ -4206,7 +4236,7 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
 	} else {
 		ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
 	}
-	put_online_cpus();
+	cpus_read_unlock();
 
 	return ret;
 }
@@ -4362,7 +4392,7 @@ static bool pwq_busy(struct pool_workqueue *pwq)
 
 	if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1))
 		return true;
-	if (pwq->nr_active || !list_empty(&pwq->delayed_works))
+	if (pwq->nr_active || !list_empty(&pwq->inactive_works))
 		return true;
 
 	return false;
@@ -4558,7 +4588,7 @@ bool workqueue_congested(int cpu, struct workqueue_struct *wq)
 	else
 		pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
 
-	ret = !list_empty(&pwq->delayed_works);
+	ret = !list_empty(&pwq->inactive_works);
 	preempt_enable();
 	rcu_read_unlock();
 
@@ -4754,11 +4784,11 @@ static void show_pwq(struct pool_workqueue *pwq)
 		pr_cont("\n");
 	}
 
-	if (!list_empty(&pwq->delayed_works)) {
+	if (!list_empty(&pwq->inactive_works)) {
 		bool comma = false;
 
-		pr_info("    delayed:");
-		list_for_each_entry(work, &pwq->delayed_works, entry) {
+		pr_info("    inactive:");
+		list_for_each_entry(work, &pwq->inactive_works, entry) {
 			pr_cont_work(comma, work);
 			comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
 		}
@@ -4788,7 +4818,7 @@ void show_workqueue_state(void)
 		bool idle = true;
 
 		for_each_pwq(pwq, wq) {
-			if (pwq->nr_active || !list_empty(&pwq->delayed_works)) {
+			if (pwq->nr_active || !list_empty(&pwq->inactive_works)) {
 				idle = false;
 				break;
 			}
@@ -4800,7 +4830,7 @@ void show_workqueue_state(void)
 
 		for_each_pwq(pwq, wq) {
 			raw_spin_lock_irqsave(&pwq->pool->lock, flags);
-			if (pwq->nr_active || !list_empty(&pwq->delayed_works))
+			if (pwq->nr_active || !list_empty(&pwq->inactive_works))
 				show_pwq(pwq);
 			raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
 			/*
@@ -5168,10 +5198,10 @@ long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
 {
 	long ret = -ENODEV;
 
-	get_online_cpus();
+	cpus_read_lock();
 	if (cpu_online(cpu))
 		ret = work_on_cpu(cpu, fn, arg);
-	put_online_cpus();
+	cpus_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(work_on_cpu_safe);
@@ -5183,7 +5213,7 @@ EXPORT_SYMBOL_GPL(work_on_cpu_safe);
  * freeze_workqueues_begin - begin freezing workqueues
  *
  * Start freezing workqueues.  After this function returns, all freezable
- * workqueues will queue new works to their delayed_works list instead of
+ * workqueues will queue new works to their inactive_works list instead of
  * pool->worklist.
  *
  * CONTEXT:
@@ -5331,7 +5361,7 @@ static int workqueue_apply_unbound_cpumask(void)
  *  the affinity of all unbound workqueues.  This function check the @cpumask
  *  and apply it to all unbound workqueues and updates all pwqs of them.
  *
- *  Retun:	0	- Success
+ *  Return:	0	- Success
  *  		-EINVAL	- Invalid @cpumask
  *  		-ENOMEM	- Failed to allocate memory for attrs or pwqs.
  */
@@ -5443,7 +5473,7 @@ static ssize_t wq_pool_ids_show(struct device *dev,
 	const char *delim = "";
 	int node, written = 0;
 
-	get_online_cpus();
+	cpus_read_lock();
 	rcu_read_lock();
 	for_each_node(node) {
 		written += scnprintf(buf + written, PAGE_SIZE - written,
@@ -5453,7 +5483,7 @@ static ssize_t wq_pool_ids_show(struct device *dev,
 	}
 	written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
 	rcu_read_unlock();
-	put_online_cpus();
+	cpus_read_unlock();
 
 	return written;
 }
@@ -5902,6 +5932,13 @@ static void __init wq_numa_init(void)
 		return;
 	}
 
+	for_each_possible_cpu(cpu) {
+		if (WARN_ON(cpu_to_node(cpu) == NUMA_NO_NODE)) {
+			pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
+			return;
+		}
+	}
+
 	wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs();
 	BUG_ON(!wq_update_unbound_numa_attrs_buf);
 
@@ -5919,11 +5956,6 @@ static void __init wq_numa_init(void)
 
 	for_each_possible_cpu(cpu) {
 		node = cpu_to_node(cpu);
-		if (WARN_ON(node == NUMA_NO_NODE)) {
-			pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
-			/* happens iff arch is bonkers, let's just proceed */
-			return;
-		}
 		cpumask_set_cpu(cpu, tbl[node]);
 	}
 
diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h
index 498de0e909a4..e00b1204a8e9 100644
--- a/kernel/workqueue_internal.h
+++ b/kernel/workqueue_internal.h
@@ -30,7 +30,8 @@ struct worker {
 
 	struct work_struct	*current_work;	/* L: work being processed */
 	work_func_t		current_func;	/* L: current_work's fn */
-	struct pool_workqueue	*current_pwq; /* L: current_work's pwq */
+	struct pool_workqueue	*current_pwq;	/* L: current_work's pwq */
+	unsigned int		current_color;	/* L: current_work's color */
 	struct list_head	scheduled;	/* L: scheduled works */
 
 	/* 64 bytes boundary on 64bit, 32 on 32bit */