[RESEND PATCH v1 2/7] vhost: Add kthread support in function vhost_worker_queue()

Cindy Lu
2024-09-09T02:02:08Z

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

The old function vhost_work_queue() was change to support task in
commit 6e890c5d5021 ('vhost: use vhost_tasks for worker threads')
changed in
commit f9010dbdc ('fork, vhost: Use CLONE_THREAD to fix freezer/ps regression')
and also was change the name of function to vhost_worker_queue() in
commit 0921dddcb5 (vhost: take worker or vq instead of dev for queueing)

Signed-off-by: Cindy Lu <lulu@redhat.com>
---
drivers/vhost/vhost.c | 30 ++++++++++++++++++++++++++++--
drivers/vhost/vhost.h | 1 +
2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index be43181af659..ab4608fcf86b 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -236,8 +236,8 @@ void vhost_poll_stop(struct vhost_poll *poll)
}
EXPORT_SYMBOL_GPL(vhost_poll_stop);

-static void vhost_worker_queue(struct vhost_worker *worker,
- struct vhost_work *work)
+static void vhost_worker_queue_task(struct vhost_worker *worker,
+ struct vhost_work *work)
{
if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
/* We can only add the work to the list after we're
@@ -249,6 +249,32 @@ static void vhost_worker_queue(struct vhost_worker *worker,
}
}

+static void vhost_work_queue_kthread(struct vhost_worker *worker,
+ struct vhost_work *work)
+{
+ if (!worker)
+ return;
+
+ if (!test_and_set_bit(VHOST_WORK_QUEUED, &work->flags)) {
+ /* We can only add the work to the list after we're
+ * sure it was not in the list.
+ * test_and_set_bit() implies a memory barrier.
+ */
+ llist_add(&work->node, &worker->work_list);
+
+ wake_up_process(worker->task);
+ }
+}
+
+static void vhost_worker_queue(struct vhost_worker *worker,
+ struct vhost_work *work)
+{
+ if (enforce_kthread) {
+ vhost_work_queue_kthread(worker, work);
+ } else {
+ vhost_worker_queue_task(worker, work);
+ }
+}
bool vhost_vq_work_queue(struct vhost_virtqueue *vq, struct vhost_work *work)
{
struct vhost_worker *worker;
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index bb75a292d50c..c7f126fd09e8 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -27,6 +27,7 @@ struct vhost_work {
};

struct vhost_worker {
+ struct task_struct *task;
struct vhost_task *vtsk;
struct vhost_dev *dev;
/* Used to serialize device wide flushing with worker swapping. */
--
2.45.0