linux-kernel - [PATCH v2 3/7] vhost: Add kthread support in function vhost_workers

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Message-ID: <20241004015937.2286459-4-lulu@redhat.com>
Date: Fri,  4 Oct 2024 09:58:17 +0800
From: Cindy Lu <lulu@...hat.com>
To: lulu@...hat.com,
	jasowang@...hat.com,
	mst@...hat.com,
	michael.christie@...cle.com,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: [PATCH v2 3/7] vhost: Add kthread support in function vhost_workers_free()

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.

The old function vhost_workers_free was change to support task in
commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads")
also changed in
commit a284f09effea ("vhost: Fix crash during early vhost_transport_send_pkt calls")
change to xarray in
commit 1cdaafa1b8b4 ("vhost: replace single worker pointer with xarray")

Signed-off-by: Cindy Lu <lulu@...hat.com>
---
 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 ad359d4b725f..fed6671c1ffb 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -648,8 +648,21 @@ 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;
@@ -660,7 +673,7 @@ 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;
@@ -675,10 +688,36 @@ 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 (enforce_inherit_owner)
+		vhost_workers_free_task(dev);
+	else
+		vhost_workers_free_kthread(dev);
+}
 static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
 {
 	struct vhost_worker *worker;
@@ -846,7 +885,10 @@ static int vhost_free_worker(struct vhost_dev *dev,
 	__vhost_worker_flush(worker);
 	mutex_unlock(&worker->mutex);
 
-	vhost_worker_destroy(dev, worker);
+	if (enforce_inherit_owner)
+		vhost_worker_destroy_task(dev, worker);
+	else
+		vhost_worker_destroy_kthread(dev, worker);
 	return 0;
 }
 
-- 
2.45.0