Re: [PATCH v4 5/8] vhost: Add kthread support in function vhost_worker_queue()

Stefano Garzarella
2024-12-10T17:54:30Z

On Wed, Dec 11, 2024 at 12:41:44AM +0800, Cindy Lu wrote:
>The function vhost_worker_queue() uses a function pointer in
>vhost_worker, which is initialized based on the inherit_owner
>value.
>
>Signed-off-by: Cindy Lu <lulu@redhat.com>
>---
> drivers/vhost/vhost.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
>index 0175bbf4d8b3..d1aec41bcd56 100644
>--- a/drivers/vhost/vhost.c
>+++ b/drivers/vhost/vhost.c
>@@ -237,13 +237,16 @@ EXPORT_SYMBOL_GPL(vhost_poll_stop);
> static void vhost_worker_queue(struct vhost_worker *worker,
> struct vhost_work *work)
> {
>+ if (!worker)
>+ return;
>+

In which scenario can `worker` be NULL?

I would like to better understand why it couldn't happen before and now
it can.

Thanks,
Stefano

> 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);
>- vhost_task_wake(worker->vtsk);
>+ worker->task_wakeup(worker);
> }
> }
>
>--
>2.45.0
>