linux-kernel - Re: [PATCH RESEND v10 0/3] vhost: Add support of kthread API

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Message-ID: <CAPpAL=w24Wwq8Qa9uQr8OQqdg8vMiK0FSOUGdCHAvB0O2B_T7Q@mail.gmail.com>
Date: Wed, 4 Jun 2025 14:00:57 +0800
From: Lei Yang <leiyang@...hat.com>
To: Cindy Lu <lulu@...hat.com>
Cc: jasowang@...hat.com, 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 RESEND v10 0/3] vhost: Add support of kthread API

Tested this patch with virtio-net regression tests, everything works fine.

Tested-by: Lei Yang <leiyang@...hat.com>

On Sat, May 31, 2025 at 5:58 PM Cindy Lu <lulu@...hat.com> 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.
>
> 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.
>
> 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
>
> Changelog v8:
>  1. Rebased on the latest kernel
>  2. Address some other comments
>
> Changelog v9:
>  1. Rebased on the latest kernel.
>  2. Squashed patches 6‑7.
>  3. Squashed patches 2‑4.
>  4. Minor fixes in commit log
>
>
> Changelog v10:
>  1.Add support for the module_param.
>  2.Squash patches 3 and 4.
>  3.Make minor fixes in the commit log.
>  4.Fix the mismatched tabs in Kconfig.
>  5.Rebase on the latest kernel.
>
> Tested with QEMU with kthread mode/task mode/kthread+task mode
>
> Cindy Lu (3):
>   vhost: Add a new modparam to allow userspace select kthread
>   vhost: Reintroduce kthread mode support in vhost
>   vhost: Add new UAPI to select kthread mode and KConfig to enable this
>     IOCTL
>
>  drivers/vhost/Kconfig      |  13 +++
>  drivers/vhost/vhost.c      | 223 +++++++++++++++++++++++++++++++++----
>  drivers/vhost/vhost.h      |  22 ++++
>  include/uapi/linux/vhost.h |  16 +++
>  4 files changed, 255 insertions(+), 19 deletions(-)
>
> --
> 2.45.0
>
>