Re: [PATCH v8 5/8] vhost: Reintroduce kthread mode support in vhost

Cindy Lu
2025-04-07T03:15:09Z

On Tue, Apr 1, 2025 at 9:51 PM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> On Fri, Mar 28, 2025 at 06:02:49PM +0800, Cindy Lu wrote:
> >This commit restores the previously removed functions kthread
> >wake/stop/create, and use ops structure vhost_worker_ops to
> >manage worker wakeup, stop and creation. The function
> >vhost_worker_create initializes these ops pointers based on
> >the value of inherit_owner
> >
> >The old function was remove in
>
> nit: s/remove/removed
>
> >commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads")
> >
> >Signed-off-by: Cindy Lu <lulu@redhat.com>
> >---
> > drivers/vhost/vhost.c | 48 ++++++++++++++++++++++++++++++++++++++++++-
> > drivers/vhost/vhost.h | 1 +
> > 2 files changed, 48 insertions(+), 1 deletion(-)
> >
> >diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> >index c162ad772f8f..be97028a8baf 100644
> >--- a/drivers/vhost/vhost.c
> >+++ b/drivers/vhost/vhost.c
> >@@ -734,11 +734,21 @@ static void vhost_task_wakeup(struct vhost_worker *worker)
> > return vhost_task_wake(worker->vtsk);
> > }
> >
> >+static void vhost_kthread_wakeup(struct vhost_worker *worker)
> >+{
> >+ wake_up_process(worker->kthread_task);
> >+}
> >+
> > static void vhost_task_do_stop(struct vhost_worker *worker)
> > {
> > return vhost_task_stop(worker->vtsk);
> > }
> >
> >+static void vhost_kthread_do_stop(struct vhost_worker *worker)
> >+{
> >+ kthread_stop(worker->kthread_task);
> >+}
> >+
> > static int vhost_task_worker_create(struct vhost_worker *worker,
> > struct vhost_dev *dev, const char *name)
> > {
> >@@ -762,6 +772,41 @@ static int vhost_task_worker_create(struct vhost_worker *worker,
> > return 0;
> > }
> >
> >+static int vhost_kthread_worker_create(struct vhost_worker *worker,
> >+ struct vhost_dev *dev, const char *name)
> >+{
> >+ struct task_struct *task;
> >+ u32 id;
> >+ int ret;
> >+
> >+ task = kthread_create(vhost_run_work_kthread_list, worker, "%s", name);
> >+ if (IS_ERR(task))
> >+ return PTR_ERR(task);
> >+
> >+ worker->kthread_task = task;
> >+ wake_up_process(task);
> >+ ret = xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL);
> >+ if (ret < 0)
> >+ goto stop_worker;
> >+
> >+ ret = vhost_attach_task_to_cgroups(worker);
> >+ if (ret)
> >+ goto stop_worker;
> >+
> >+ worker->id = id;
> >+ return 0;
> >+
> >+stop_worker:
> >+ vhost_kthread_do_stop(worker);
> >+ return ret;
> >+}
> >+
> >+static const struct vhost_worker_ops kthread_ops = {
> >+ .create = vhost_kthread_worker_create,
> >+ .stop = vhost_kthread_do_stop,
> >+ .wakeup = vhost_kthread_wakeup,
> >+};
> >+
> > static const struct vhost_worker_ops vhost_task_ops = {
> > .create = vhost_task_worker_create,
> > .stop = vhost_task_do_stop,
> >@@ -773,7 +818,8 @@ static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
> > struct vhost_worker *worker;
> > char name[TASK_COMM_LEN];
> > int ret;
> >- const struct vhost_worker_ops *ops = &vhost_task_ops;
> >+ const struct vhost_worker_ops *ops =
> >+ dev->inherit_owner ? &vhost_task_ops : &kthread_ops;
> >
> > worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
> > if (!worker)
> >diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> >index 98895e299efa..af4b2f7d3b91 100644
> >--- a/drivers/vhost/vhost.h
> >+++ b/drivers/vhost/vhost.h
> >@@ -37,6 +37,7 @@ struct vhost_worker_ops {
> > };
> >
> > struct vhost_worker {
> >+ struct task_struct *kthread_task;
> ^
> nit: I'm not a fan of tabs, but here all the other fields have it, so I
> would put it in.
>
Sure,will fix this
Thanks
Cindy
> > struct vhost_task *vtsk;
> > struct vhost_dev *dev;
> > /* Used to serialize device wide flushing with worker swapping. */
> >--
> >2.45.0
> >
>
> The patch LGTM:
>
> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
>