netdev - Re: [PATCH v5 3/6] vhost: Add the cgroup related function

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Message-ID: <CACGkMEuGLDmYq6igW3U6dKGd0WYmtQgzNu6C02ae5ZRP0_Nq+w@mail.gmail.com>
Date: Wed, 8 Jan 2025 15:39:50 +0800
From: Jason Wang <jasowang@...hat.com>
To: Cindy Lu <lulu@...hat.com>
Cc: mst@...hat.com, michael.christie@...cle.com, sgarzare@...hat.com, 
	linux-kernel@...r.kernel.org, virtualization@...ts.linux-foundation.org, 
	netdev@...r.kernel.org
Subject: Re: [PATCH v5 3/6] vhost: Add the cgroup related function

On Wed, Jan 8, 2025 at 10:57 AM Cindy Lu <lulu@...hat.com> wrote:
>
> On Thu, Jan 2, 2025 at 11:29 AM Jason Wang <jasowang@...hat.com> wrote:
> >
> > On Mon, Dec 30, 2024 at 8:45 PM Cindy Lu <lulu@...hat.com> wrote:
> > >
> > > 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 <lulu@...hat.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)
> > > +{
> > > +       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
> >
> > """
> > > 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

Any reason it can't work here?

Thanks

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