On Thu, Jun 16, 2016 at 01:17:25PM +0200, Petr Mladek wrote:

+/**
+ * kthread_drain_worker - drain a kthread worker
+ * @worker: worker to be drained
+ *
+ * Wait until there is no work queued for the given kthread worker.
+ * @worker is flushed repeatedly until it becomes empty.  The number
+ * of flushing is determined by the depth of chaining and should
+ * be relatively short.  Whine if it takes too long.
+ *

+ * The caller is responsible for blocking all users of this kthread
+ * worker from queuing new works. Also it is responsible for blocking
+ * the already queued works from an infinite re-queuing!

This, I really dislike that. And it makes the kthread_destroy_worker()
from the next patch unnecessarily fragile.

Why not add a kthread_worker::blocked flag somewhere and refuse/WARN
kthread_queue_work() when that is set.

+ */
+void kthread_drain_worker(struct kthread_worker *worker)
+{
+	int flush_cnt = 0;
+
+	spin_lock_irq(&worker->lock);
+
+	while (!list_empty(&worker->work_list)) {
+		spin_unlock_irq(&worker->lock);
+
+		kthread_flush_worker(worker);
+		WARN_ONCE(flush_cnt++ > 10,
+			  "kthread worker %s: kthread_drain_worker() isn't complete after %u tries\n",
+			  worker->task->comm, flush_cnt);
+
+		spin_lock_irq(&worker->lock);
+	}
+
+	spin_unlock_irq(&worker->lock);
+}
+EXPORT_SYMBOL(kthread_drain_worker);
-- 
1.8.5.6

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>