Re: [PATCH v4 3/8] vhost: Add the cgroup related function

Stefano Garzarella
2024-12-10T17:53:14Z

On Wed, Dec 11, 2024 at 12:41:42AM +0800, Cindy Lu wrote:
>Add back the previously removed cgroup function to support the kthread

nit: missing . at the end

>The biggest change for this part is in vhost_attach_cgroups() and
>vhost_attach_task_to_cgroups().

It's not clear what the big change is, is there a piece missing?

>
>The old function was remove in

s/remove/removed

BTW which is the old function?

>commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads")
>
>Signed-off-by: Cindy Lu <lulu@redhat.com>
>---
> 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)

This function looks renamed, should we mention in the commit
description?

>+{
>+ 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);

IIUC this block is the old "vhost_dev_flush", right?

Maybe we should mention also that in the commit description.

>+
>+ return attach.ret;
>+}
>+
> /* Caller should have device mutex */
> bool vhost_dev_has_owner(struct vhost_dev *dev)
> {
>--
>2.45.0
>