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Date: Tue, 3 Jun 2025 08:34:23 +0100
From: Simon Horman <horms@kernel.org>
To: Cindy Lu <lulu@redhat.com>
Cc: jasowang@redhat.com, mst@redhat.com, michael.christie@oracle.com,
	sgarzare@redhat.com, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, netdev@vger.kernel.org
Subject: Re: [PATCH RESEND v10 1/3] vhost: Add a new modparam to allow
 userspace select kthread
Message-ID: <20250603073423.GX1484967@horms.kernel.org>
References: <20250531095800.160043-1-lulu@redhat.com>
 <20250531095800.160043-2-lulu@redhat.com>
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In-Reply-To: <20250531095800.160043-2-lulu@redhat.com>

On Sat, May 31, 2025 at 05:57:26PM +0800, Cindy Lu wrote:
> The vhost now uses vhost_task and workers as a child of the owner thread.
> While this aligns with containerization principles, it confuses some
> legacy userspace applications, therefore, we are reintroducing kthread
> API support.
> 
> Add a new module parameter to allow userspace to select behavior
> between using kthread and task.
> 
> By default, this parameter is set to true (task mode). This means the
> default behavior remains unchanged by this patch.
> 
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>  drivers/vhost/vhost.c |  5 +++++
>  drivers/vhost/vhost.h | 10 ++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 3a5ebb973dba..240ba78b1e3f 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -41,6 +41,10 @@ static int max_iotlb_entries = 2048;
>  module_param(max_iotlb_entries, int, 0444);
>  MODULE_PARM_DESC(max_iotlb_entries,
>  	"Maximum number of iotlb entries. (default: 2048)");
> +bool inherit_owner_default = true;

Hi Cindy,

I don't mean to block progress of this patchset.
But it looks like inherit_owner_default can be static.

Flagged by Sparse.

> +module_param(inherit_owner_default, bool, 0444);
> +MODULE_PARM_DESC(inherit_owner_default,
> +		 "Set task mode as the default(default: Y)");

...