Re: [dpdk-dev] [PATCH 2/2] vhost: add thread unsafe async registration functions

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 5/28/21 10:11 AM, Jiayu Hu wrote:
> This patch is to add thread unsafe version for async register and

s/is to add/adds/

> unregister functions.
> 
> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> ---
>  doc/guides/prog_guide/vhost_lib.rst |  12 +++
>  lib/vhost/rte_vhost_async.h         |  42 ++++++++++
>  lib/vhost/version.map               |   4 +
>  lib/vhost/vhost.c                   | 161 +++++++++++++++++++++++++++---------
>  4 files changed, 178 insertions(+), 41 deletions(-)
> 
> diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
> index d18fb98..6b2745f 100644
> --- a/doc/guides/prog_guide/vhost_lib.rst
> +++ b/doc/guides/prog_guide/vhost_lib.rst
> @@ -253,6 +253,12 @@ The following is an overview of some key Vhost API functions:
>      vhost invokes this function to get the copy data completed by async
>      devices.
>  
> +* ``rte_vhost_async_channel_register_thread_unsafe(vid, queue_id, features, ops)``
> +  Register a vhost queue with async copy device channel without
> +  performing any locking.
> +
> +  This function is only safe to call from within vhost callback functions.

I'm not sure with this, AFAICS .new_device() is called without the lock
held, so is that safe? Since .new_device() is the first time the app
gets required device info to use the Vhost API, that might not be an
issue, though.