Re: [dpdk-dev] [PATCH v1] vhost: fix async callback return type define

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

> -----Original Message-----
> From: Fu, Patrick <patrick.fu@intel.com>
> Sent: Thursday, July 23, 2020 1:39 PM
> To: dev@dpdk.org; maxime.coquelin@redhat.com; Xia, Chenbo
> <chenbo.xia@intel.com>
> Cc: Fu, Patrick <patrick.fu@intel.com>
> Subject: [PATCH v1] vhost: fix async callback return type define
> 
> From: Patrick Fu <patrick.fu@intel.com>
> 
> The async copy device callbacks are used by async APIs to transfer data and
> check completion status. Async APIs return the number of packets successfully
> processed to the caller applications and no error (negative) value is allowed for
> API return value. Thus, negative return values from async device callbacks don't
> have meaningful usage, while adding overhead in checking the return value
> validity. This patch change the callback return values from "int" to "uint32_t" to
> get aligned with async API definition.
> 
> Fixes: 78639d54563a ("vhost: introduce async enqueue registration API")
> 
> Signed-off-by: Patrick Fu <patrick.fu@intel.com>
> ---
>  lib/librte_vhost/rte_vhost_async.h | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/librte_vhost/rte_vhost_async.h
> b/lib/librte_vhost/rte_vhost_async.h
> index c8ad8dbc7..66d258abe 100644
> --- a/lib/librte_vhost/rte_vhost_async.h
> +++ b/lib/librte_vhost/rte_vhost_async.h
> @@ -59,9 +59,9 @@ struct rte_vhost_async_channel_ops {
>  	 * @param count
>  	 *  number of elements in the "descs" array
>  	 * @return
> -	 *  -1 on failure, number of descs processed on success
> +	 *  number of descs processed on success
>  	 */
> -	int (*transfer_data)(int vid, uint16_t queue_id,
> +	uint32_t (*transfer_data)(int vid, uint16_t queue_id,
>  		struct rte_vhost_async_desc *descs,
>  		struct rte_vhost_async_status *opaque_data,
>  		uint16_t count);
> @@ -70,15 +70,15 @@ struct rte_vhost_async_channel_ops {
>  	 * @param vid
>  	 *  id of vhost device to check copy completion
>  	 * @param queue_id
> -	 *  queue id to check copyp completion
> +	 *  queue id to check copy completion
>  	 * @param opaque_data
>  	 *  buffer to receive the opaque data pair from DMA engine
>  	 * @param max_packets
>  	 *  max number of packets could be completed
>  	 * @return
> -	 *  -1 on failure, number of iov segments completed on success
> +	 *  number of iov segments completed on success
>  	 */
> -	int (*check_completed_copies)(int vid, uint16_t queue_id,
> +	uint32_t (*check_completed_copies)(int vid, uint16_t queue_id,
>  		struct rte_vhost_async_status *opaque_data,
>  		uint16_t max_packets);
>  };
> --
> 2.18.4

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>