On Wed, Jun 18, 2025 at 8:06 PM Nicolas Dichtel
<nicolas.dichtel@xxxxxxxxx> wrote:
>
> Le 16/06/2025 à 08:28, Cindy Lu a écrit :
> > This patch reintroduces kthread mode for vhost workers and provides
> > configuration to select between kthread and task worker.
> >
> > - Add 'fork_owner' parameter to vhost_dev to let users select kthread
> > or task mode. Default mode is task mode(VHOST_FORK_OWNER_TASK).
> >
> > - Reintroduce kthread mode support:
> > * Bring back the original vhost_worker() implementation,
> > and renamed to vhost_run_work_kthread_list().
> > * Add cgroup support for the kthread
> > * Introduce struct vhost_worker_ops:
> > - Encapsulates create / stop / wake‑up callbacks.
> > - vhost_worker_create() selects the proper ops according to
> > inherit_owner.
> >
> > - Userspace configuration interface:
> > * New IOCTLs:
> > - VHOST_SET_FORK_FROM_OWNER lets userspace select task mode
> > (VHOST_FORK_OWNER_TASK) or kthread mode (VHOST_FORK_OWNER_KTHREAD)
> > - VHOST_GET_FORK_FROM_OWNER reads the current worker mode
> > * Expose module parameter 'fork_from_owner_default' to allow system
> > administrators to configure the default mode for vhost workers
> > * Kconfig option CONFIG_VHOST_ENABLE_FORK_OWNER_CONTROL controls whether
> > these IOCTLs and the parameter are available (for distros that may
> > want to disable them)
> >
> > - The VHOST_NEW_WORKER functionality requires fork_owner to be set
> > to true, with validation added to ensure proper configuration
> >
> > This partially reverts or improves upon:
> > commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads")
> > commit 1cdaafa1b8b4 ("vhost: replace single worker pointer with xarray")
> >
> > Signed-off-by: Cindy Lu <lulu@xxxxxxxxxx>
> > ---
> > drivers/vhost/Kconfig | 17 +++
> > drivers/vhost/vhost.c | 244 ++++++++++++++++++++++++++++++++++---
> > drivers/vhost/vhost.h | 22 ++++
> > include/uapi/linux/vhost.h | 29 +++++
> > 4 files changed, 294 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> > index 020d4fbb947c..1b3602b1f8e2 100644
> > --- a/drivers/vhost/Kconfig
> > +++ b/drivers/vhost/Kconfig
> > @@ -95,4 +95,21 @@ config VHOST_CROSS_ENDIAN_LEGACY
> >
> > If unsure, say "N".
> >
> > +config VHOST_ENABLE_FORK_OWNER_CONTROL
> > + bool "Enable VHOST_ENABLE_FORK_OWNER_CONTROL"
> > + default n
> Why disabling this option by default?
I think we should enable this by default.
Thanks
>
> Regards,
> Nicolas
>
