On Wed, Jan 8, 2025 at 10:35 PM Stefano Garzarella [off-list ref] wrote:

On Mon, Dec 30, 2024 at 08:43:51PM +0800, Cindy Lu wrote:

quoted

Restore the previously removed functions kthread_wakeup and
kthread_stop, and add two new function pointers to wake up and stop
the workers. The function vhost_worker_create will initialize these
pointers based on the value of inherit_owner.

The functions vhost_worker_queue() and vhost_worker_destroy() will
use the function pointer in vhost_worker, which is initialized
according to the inherit_owner value.

Signed-off-by: Cindy Lu <redacted>
---
drivers/vhost/vhost.c | 84 ++++++++++++++++++++++++++++++++++---------
drivers/vhost/vhost.h |  3 ++
2 files changed, 71 insertions(+), 16 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 812dfd218bc2..ff17c42e2d1a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c

[...]

quoted

@@ -736,27 +758,57 @@ static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
      worker->dev = dev;
      snprintf(name, sizeof(name), "vhost-%d", current->pid);

-      vtsk = vhost_task_create(vhost_run_work_list, vhost_worker_killed,
-                               worker, name);
-      if (!vtsk)
-              goto free_worker;
-
      mutex_init(&worker->mutex);
      init_llist_head(&worker->work_list);
      worker->kcov_handle = kcov_common_handle();
-      worker->vtsk = vtsk;
+    /*
+     * If inherit_owner is true we use vhost_tasks to create
+     * the worker so all settings/limits like cgroups, NPROC,
+     * scheduler, etc are inherited from the owner.
+     * If false,we use kthreads and only attach to the same
+     * cgroups as the owner for compat with older kernels.
+     */

This comment block seems to have incorrect indentation, perhaps you need
to replace the spaces with at least one tab.

sure will do
Thanks
cindy

quoted

+      if (dev->inherit_owner) {
+              vtsk = vhost_task_create(vhost_run_work_list,
+                                       vhost_worker_killed, worker, name);
+              if (!vtsk)
+                      goto free_worker;
+
+              worker->vtsk = vtsk;
+              worker->worker_wakeup = vhost_task_wakeup_fn;
+              worker->worker_stop = vhost_task_stop_fn;
+
+              vhost_task_start(vtsk);
+              ret = xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b,
+                             GFP_KERNEL);
+              if (ret < 0)
+                      goto stop_worker;
+      } else {
+              task = kthread_create(vhost_run_work_kthread_list, worker,
+                                    "vhost-%d", current->pid);
+              if (IS_ERR(task)) {
+                      ret = PTR_ERR(task);
+                      goto free_worker;
+              }
+              worker->kthread_task = task;
+              worker->worker_wakeup = vhost_kthread_wakeup_fn;
+              worker->worker_stop = vhost_kthread_stop_fn;

-      vhost_task_start(vtsk);
+              wake_up_process(task);
+              ret = xa_alloc(&dev->worker_xa, &id, worker,
xa_limit_32b,
+                             GFP_KERNEL);
+              if (ret < 0)
+                      goto stop_worker;

-      ret = xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL);
-      if (ret < 0)
-              goto stop_worker;
-      worker->id = id;
+              ret = vhost_attach_task_to_cgroups(worker);
+              if (ret)
+                      goto stop_worker;
+      }

+      worker->id = id;
      return worker;
-
stop_worker:
-      vhost_task_stop(vtsk);
+      worker->worker_stop(worker);
free_worker:
      kfree(worker);
      return NULL;

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index c650c4506c70..63b1da08a2b0 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h

@@ -27,6 +27,7 @@ struct vhost_work {

};

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

@@ -36,6 +37,8 @@ struct vhost_worker {
      u32                     id;
      int                     attachment_cnt;
      bool                    killed;
+      void (*worker_wakeup)(struct vhost_worker *worker);
+      void (*worker_stop)(struct vhost_worker *worker);

};

/* Poll a file (eventfd or socket) */
--
2.45.0