Merge branch 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue updates from Tejun Heo:
 "rcu_work addition and a couple trivial changes"

* 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: remove the comment about the old manager_arb mutex
  workqueue: fix the comments of nr_idle
  fs/aio: Use rcu_work instead of explicit rcu and work item
  cgroup: Use rcu_work instead of explicit rcu and work item
  RCU, workqueue: Implement rcu_work

1 files changed, 56 insertions, 4 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 254e636a3d6b..ca7959be8aaa 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -153,10 +153,9 @@ struct worker_pool {
 	unsigned long		watchdog_ts;	/* L: watchdog timestamp */
 
 	struct list_head	worklist;	/* L: list of pending works */
-	int			nr_workers;	/* L: total number of workers */
 
-	/* nr_idle includes the ones off idle_list for rebinding */
-	int			nr_idle;	/* L: currently idle ones */
+	int			nr_workers;	/* L: total number of workers */
+	int			nr_idle;	/* L: currently idle workers */
 
 	struct list_head	idle_list;	/* X: list of idle workers */
 	struct timer_list	idle_timer;	/* L: worker idle timeout */
@@ -166,7 +165,6 @@ struct worker_pool {
 	DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
 						/* L: hash of busy workers */
 
-	/* see manage_workers() for details on the two manager mutexes */
 	struct worker		*manager;	/* L: purely informational */
 	struct mutex		attach_mutex;	/* attach/detach exclusion */
 	struct list_head	workers;	/* A: attached workers */
@@ -1604,6 +1602,40 @@ bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
 }
 EXPORT_SYMBOL_GPL(mod_delayed_work_on);
 
+static void rcu_work_rcufn(struct rcu_head *rcu)
+{
+	struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu);
+
+	/* read the comment in __queue_work() */
+	local_irq_disable();
+	__queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work);
+	local_irq_enable();
+}
+
+/**
+ * queue_rcu_work - queue work after a RCU grace period
+ * @wq: workqueue to use
+ * @rwork: work to queue
+ *
+ * Return: %false if @rwork was already pending, %true otherwise.  Note
+ * that a full RCU grace period is guaranteed only after a %true return.
+ * While @rwork is guarnateed to be executed after a %false return, the
+ * execution may happen before a full RCU grace period has passed.
+ */
+bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork)
+{
+	struct work_struct *work = &rwork->work;
+
+	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
+		rwork->wq = wq;
+		call_rcu(&rwork->rcu, rcu_work_rcufn);
+		return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL(queue_rcu_work);
+
 /**
  * worker_enter_idle - enter idle state
  * @worker: worker which is entering idle state
@@ -3001,6 +3033,26 @@ bool flush_delayed_work(struct delayed_work *dwork)
 }
 EXPORT_SYMBOL(flush_delayed_work);
 
+/**
+ * flush_rcu_work - wait for a rwork to finish executing the last queueing
+ * @rwork: the rcu work to flush
+ *
+ * Return:
+ * %true if flush_rcu_work() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_rcu_work(struct rcu_work *rwork)
+{
+	if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) {
+		rcu_barrier();
+		flush_work(&rwork->work);
+		return true;
+	} else {
+		return flush_work(&rwork->work);
+	}
+}
+EXPORT_SYMBOL(flush_rcu_work);
+
 static bool __cancel_work(struct work_struct *work, bool is_dwork)
 {
 	unsigned long flags;