Re: [dpdk-dev] [PATCH v4 3/3] vhost: add thread unsafe async registeration functions

["Xia, Chenbo" <chenbo.xia@intel.com>]

Hi Jiayu,

> -----Original Message-----
> From: Hu, Jiayu <jiayu.hu@intel.com>
> Sent: Tuesday, July 13, 2021 3:46 PM
> To: dev@dpdk.org
> Cc: maxime.coquelin@redhat.com; Xia, Chenbo <chenbo.xia@intel.com>; Hu, Jiayu
> <jiayu.hu@intel.com>
> Subject: [PATCH v4 3/3] vhost: add thread unsafe async registeration functions
> 
> This patch adds thread unsafe version for async register and
> 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         |  39 ++++++++++
>  lib/vhost/version.map               |   4 +
>  lib/vhost/vhost.c                   | 146 +++++++++++++++++++++++++++--------
> -
>  4 files changed, 167 insertions(+), 34 deletions(-)
> 
> diff --git a/doc/guides/prog_guide/vhost_lib.rst
> b/doc/guides/prog_guide/vhost_lib.rst
> index affdc57..ffe09a3 100644
> --- a/doc/guides/prog_guide/vhost_lib.rst
> +++ b/doc/guides/prog_guide/vhost_lib.rst
> @@ -256,6 +256,12 @@ 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, config,
> ops)``
> +  Register a vhost queue with async copy device channel without

'Register an async copy device channel for a vhost queue' sounds better 

> +  performing any locking.
> +
> +  This function is only safe to call from within vhost callback functions.

call in vhost callback functions?

> +
>  * ``rte_vhost_async_channel_unregister(vid, queue_id)``
> 
>    Unregister the async copy device channel from a vhost queue.
> @@ -268,6 +274,12 @@ The following is an overview of some key Vhost API
> functions:
>    devices for all vhost queues in destroy_device(), when a
>    virtio device is paused or shut down.
> 
> +* ``rte_vhost_async_channel_unregister_thread_unsafe(vid, queue_id)``
> +  Unregister the async copy device channel from a vhost queue without

for a vhost queue?

> +  performing any locking.
> +
> +  This function is only safe to call from within vhost callback functions.

Call in vhost callback functions?

And let's make it clearer. Add this: (i.e., struct vhost_device_ops)

> +
>  * ``rte_vhost_submit_enqueue_burst(vid, queue_id, pkts, count, comp_pkts,
> comp_count)``
> 
>    Submit an enqueue request to transmit ``count`` packets from host to guest
> diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
> index c93490d..e4d20a3 100644
> --- a/lib/vhost/rte_vhost_async.h
> +++ b/lib/vhost/rte_vhost_async.h
> @@ -142,6 +142,45 @@ __rte_experimental
>  int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id);
> 
>  /**
> + * register an async channel for vhost without performing any locking

register -> Register

for vhost -> for a vhost queue

> + *
> + * @note This function does not perform any locking, and is only safe to call
> + *       from within vhost callback functions.

From within -> in ?

> + *
> + * @param vid
> + *  vhost device id async channel to be attached to
> + * @param queue_id
> + *  vhost queue id async channel to be attached to
> + * @param config
> + *  DMA channel configuration

DMA -> async?

> + * @param ops
> + *  DMA operation callbacks

Async channel operation callbacks?

> + * @return
> + *  0 on success, -1 on failures
> + */
> +__rte_experimental
> +int rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id,

According to DPDK coding style. Return value should not be in the same line
of the function name. Just make a new line for it. Please check other functions like
unregister.

> +	struct rte_vhost_async_config config,
> +	struct rte_vhost_async_channel_ops *ops);
> +
> +/**
> + * unregister a dma channel for vhost without performing any lock

Unregister an async channel for a vhost queue

> + *
> + * @note This function does not perform any locking, and is only safe to call
> + *       from within vhost callback functions.

in vhost callback functions

> + *
> + * @param vid
> + *  vhost device id DMA channel to be detached

Vhost device id Async channel to be detached from

> + * @param queue_id
> + *  vhost queue id DMA channel to be detached

Ditto

> + * @return
> + *  0 on success, -1 on failures
> + */
> --
> 2.7.4