On Thu, Jan 2, 2025 at 11:29 AM Jason Wang [off-list ref] wrote:

On Mon, Dec 30, 2024 at 8:45 PM Cindy Lu [off-list ref] wrote:

quoted

Reintroduce the previously removed functions vhost_attach_cgroups_work()
and vhost_attach_cgroups() to support kthread mode. Rename
vhost_attach_cgroups() to vhost_attach_task_to_cgroups(), and include
the implementation of the old function vhost_dev_flush() in this
new function.

These function was removed in
commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads")

Signed-off-by: Cindy Lu <redacted>
---
 drivers/vhost/vhost.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 1feba29abf95..812dfd218bc2 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c

@@ -22,6 +22,7 @@
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/kthread.h>
+#include <linux/cgroup.h>
 #include <linux/module.h>
 #include <linux/sort.h>
 #include <linux/sched/mm.h>

@@ -620,6 +621,38 @@ long vhost_dev_check_owner(struct vhost_dev *dev)
 }
 EXPORT_SYMBOL_GPL(vhost_dev_check_owner);

+struct vhost_attach_cgroups_struct {
+       struct vhost_work work;
+       struct task_struct *owner;
+       int ret;
+};
+
+static void vhost_attach_cgroups_work(struct vhost_work *work)
+{
+       struct vhost_attach_cgroups_struct *s;
+
+       s = container_of(work, struct vhost_attach_cgroups_struct, work);
+       s->ret = cgroup_attach_task_all(s->owner, current);
+}
+
+static int vhost_attach_task_to_cgroups(struct vhost_worker *worker)
+{
+       struct vhost_flush_struct flush;
+       struct vhost_attach_cgroups_struct attach;
+
+       attach.owner = current;
+
+       vhost_work_init(&attach.work, vhost_attach_cgroups_work);
+       vhost_worker_queue(worker, &attach.work);
+
+       init_completion(&flush.wait_event);
+       vhost_work_init(&flush.work, vhost_flush_work);
+       vhost_worker_queue(worker, &flush.work);
+       wait_for_completion(&flush.wait_event);
+
+       return attach.ret;
+}

This seems to be inconsistent with what you said above which is

"""

quoted

These function was removed in
commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads")

"""

As 6e890c5d5021 had:

static int vhost_attach_cgroups(struct vhost_dev *dev)
{
        struct vhost_attach_cgroups_struct attach;

        attach.owner = current;
        vhost_work_init(&attach.work, vhost_attach_cgroups_work);
        vhost_work_queue(dev, &attach.work);
        vhost_dev_flush(dev);
        return attach.ret;
}

It seems current vhost_dev_flush() will still work or the open coding
of the flush logic needs to be explained.

Thanks

the current vhost_dev_flush was changed to support xarray, So it does
not work here , I will add more information here
Thanks
cindy

quoted

+
 /* Caller should have device mutex */
 bool vhost_dev_has_owner(struct vhost_dev *dev)
 {
--
2.45.0