Re: [PATCH v7 0/8] vhost: Add support of kthread API

[Cindy Lu]

On Sat, Mar 22, 2025 at 3:37 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
>
> On Sun, Mar 02, 2025 at 10:32:02PM +0800, Cindy Lu wrote:
> > In commit 6e890c5d5021 ("vhost: use vhost_tasks for worker threads"),
> > the vhost now uses vhost_task and operates as a child of the
> > owner thread. This aligns with containerization principles.
> > However, this change has caused confusion for some legacy
> > userspace applications. Therefore, we are reintroducing
> > support for the kthread API.
> >
> > In this series, a new UAPI is implemented to allow
> > userspace applications to configure their thread mode.
>
> This seems to be on top of an old tree.
> Can you rebase pls?
>
sure, I will rebase this
Thanks
Cindy
> > Changelog v2:
> >  1. Change the module_param's name to enforce_inherit_owner, and the default value is true.
> >  2. Change the UAPI's name to VHOST_SET_INHERIT_FROM_OWNER.
> >
> > Changelog v3:
> >  1. Change the module_param's name to inherit_owner_default, and the default value is true.
> >  2. Add a structure for task function; the worker will select a different mode based on the value inherit_owner.
> >  3. device will have their own inherit_owner in struct vhost_dev
> >  4. Address other comments
> >
> > Changelog v4:
> >  1. remove the module_param, only keep the UAPI
> >  2. remove the structure for task function; change to use the function pointer in vhost_worker
> >  3. fix the issue in vhost_worker_create and vhost_dev_ioctl
> >  4. Address other comments
> >
> > Changelog v5:
> >  1. Change wakeup and stop function pointers in struct vhost_worker to void.
> >  2. merging patches 4, 5, 6 in a single patch
> >  3. Fix spelling issues and address other comments.
> >
> > Changelog v6:
> >  1. move the check of VHOST_NEW_WORKER from vhost_scsi to vhost
> >  2. Change the ioctl name VHOST_SET_INHERIT_FROM_OWNER to VHOST_FORK_FROM_OWNER
> >  3. reuse the function __vhost_worker_flush
> >  4. use a ops sturct to support worker relates function
> >  5. reset the value of inherit_owner in vhost_dev_reset_owner s.
> >
> > Changelog v7:
> >  1. add a KConfig knob to disable legacy app support
> >  2. Split the changes into two patches to separately introduce the ops and add kthread support.
> >  3. Utilized INX_MAX to avoid modifications in __vhost_worker_flush
> >  4. Rebased on the latest kernel
> >  5. Address other comments
> >
> > Tested with QEMU with kthread mode/task mode/kthread+task mode
> >
> > Cindy Lu (8):
> >   vhost: Add a new parameter in vhost_dev to allow user select kthread
> >   vhost: Reintroduce vhost_worker to support kthread
> >   vhost: Add the cgroup related function
> >   vhost: Introduce vhost_worker_ops in vhost_worker
> >   vhost: Reintroduce kthread mode support in vhost
> >   vhost: uapi to control task mode (owner vs kthread)
> >   vhost: Add check for inherit_owner status
> >   vhost: Add a KConfig knob to enable IOCTL VHOST_FORK_FROM_OWNER
> >
> >  drivers/vhost/Kconfig      |  15 +++
> >  drivers/vhost/vhost.c      | 227 +++++++++++++++++++++++++++++++++----
> >  drivers/vhost/vhost.h      |  21 ++++
> >  include/uapi/linux/vhost.h |  15 +++
> >  4 files changed, 259 insertions(+), 19 deletions(-)
> >
> > --
> > 2.45.0
>