[RFC 3/7] vhost: Add kthread support in function vhost_workers_free()

[Cindy Lu <lulu@xxxxxxxxxx>]

Added back the previously removed function vhost_workers_free() and
renamed it to vhost_workers_free_khtread(). The new vhost_workers_free()
will select the different mode based on the value of the parameter.

Signed-off-by: Cindy Lu <lulu@xxxxxxxxxx>
---
 drivers/vhost/vhost.c | 52 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 5 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 6261c9df468e..77071def355c 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -647,8 +647,21 @@ static void vhost_detach_mm(struct vhost_dev *dev)
 	dev->mm = NULL;
 }
 
-static void vhost_worker_destroy(struct vhost_dev *dev,
-				 struct vhost_worker *worker)
+static void vhost_worker_destroy_kthread(struct vhost_dev *dev,
+					 struct vhost_worker *worker)
+{
+	if (!worker)
+		return;
+
+	WARN_ON(!llist_empty(&worker->work_list));
+
+	xa_erase(&dev->worker_xa, worker->id);
+	kthread_stop(worker->task);
+	kfree(worker);
+}
+
+static void vhost_worker_destroy_task(struct vhost_dev *dev,
+				      struct vhost_worker *worker)
 {
 	if (!worker)
 		return;
@@ -659,7 +672,7 @@ static void vhost_worker_destroy(struct vhost_dev *dev,
 	kfree(worker);
 }
 
-static void vhost_workers_free(struct vhost_dev *dev)
+static void vhost_workers_free_task(struct vhost_dev *dev)
 {
 	struct vhost_worker *worker;
 	unsigned long i;
@@ -674,10 +687,36 @@ static void vhost_workers_free(struct vhost_dev *dev)
 	 * created but couldn't clean up (it forgot or crashed).
 	 */
 	xa_for_each(&dev->worker_xa, i, worker)
-		vhost_worker_destroy(dev, worker);
+		vhost_worker_destroy_task(dev, worker);
 	xa_destroy(&dev->worker_xa);
 }
 
+static void vhost_workers_free_kthread(struct vhost_dev *dev)
+{
+	struct vhost_worker *worker;
+	unsigned long i;
+
+	if (!dev->use_worker)
+		return;
+
+	for (i = 0; i < dev->nvqs; i++)
+		rcu_assign_pointer(dev->vqs[i]->worker, NULL);
+	/*
+	 * Free the default worker we created and cleanup workers userspace
+	 * created but couldn't clean up (it forgot or crashed).
+	 */
+	xa_for_each(&dev->worker_xa, i, worker)
+		vhost_worker_destroy_kthread(dev, worker);
+	xa_destroy(&dev->worker_xa);
+}
+
+static void vhost_workers_free(struct vhost_dev *dev)
+{
+	if (use_kthread)
+		vhost_workers_free_kthread(dev);
+	else
+		vhost_workers_free_task(dev);
+}
 static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
 {
 	struct vhost_worker *worker;
@@ -845,7 +884,10 @@ static int vhost_free_worker(struct vhost_dev *dev,
 	__vhost_worker_flush(worker);
 	mutex_unlock(&worker->mutex);
 
-	vhost_worker_destroy(dev, worker);
+	if (use_kthread)
+		vhost_worker_destroy_kthread(dev, worker);
+	else
+		vhost_worker_destroy_task(dev, worker);
 	return 0;
 }
 
-- 
2.45.0